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Journal articles on the topic 'Cross contraction'

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1

Conley, Kevin E., and Stan L. Lindstedt. "Energy-saving mechanisms in muscle: the minimization strategy." Journal of Experimental Biology 205, no. 15 (2002): 2175–81. http://dx.doi.org/10.1242/jeb.205.15.2175.

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SUMMARYMany mechanisms reduce the cost of muscle activity. Here, we describe a set of specializations that reduce the cost of contraction in the high-frequency twitches that are used by a wide variety of animals for either sound production or flight. Minimizing the cost of these contractions means that cellular ATP production can meet ATP demand and sustain the high contractile rate. Two classes of specialization are found that minimize the contractile cost. The first class reduces the muscle work required per contraction. Light appendages such as rattles, insect limbs and membranous wings tha
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2

Hellstrand, Per. "Cross-bridge kinetics and shortening in smooth muscle." Canadian Journal of Physiology and Pharmacology 72, no. 11 (1994): 1334–37. http://dx.doi.org/10.1139/y94-192.

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Stiffness measurements were performed on smooth muscle preparations from guinea-pig taenia coli to obtain information on the number of attached cross bridges under varying contractile conditions. The normalized stiffness of the cross-bridge system in smooth muscle may be of a magnitude similar to that assumed in skeletal muscle. Transition from isometric contraction to unloaded shortening was associated with a decrease in stiffness to 50% or less of the isometric value, slightly higher than that found in skeletal muscle fibers. Comparison of phasic (5 s) and tonic (5 min) contractions showed l
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3

Fukutani, Atsuki, and Walter Herzog. "Current Understanding of Residual Force Enhancement: Cross-Bridge Component and Non-Cross-Bridge Component." International Journal of Molecular Sciences 20, no. 21 (2019): 5479. http://dx.doi.org/10.3390/ijms20215479.

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Muscle contraction is initiated by the interaction between actin and myosin filaments. The sliding of actin filaments relative to myosin filaments is produced by cross-bridge cycling, which is governed by the theoretical framework of the cross-bridge theory. The cross-bridge theory explains well a number of mechanical responses, such as isometric and concentric contractions. However, some experimental observations cannot be explained with the cross-bridge theory; for example, the increased isometric force after eccentric contractions. The steady-state, isometric force after an eccentric contra
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4

Joumaa, Venus, Ian C. Smith, Atsuki Fukutani, et al. "Effect of Active Lengthening and Shortening on Small-Angle X-ray Reflections in Skinned Skeletal Muscle Fibres." International Journal of Molecular Sciences 22, no. 16 (2021): 8526. http://dx.doi.org/10.3390/ijms22168526.

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Our purpose was to use small-angle X-ray diffraction to investigate the structural changes within sarcomeres at steady-state isometric contraction following active lengthening and shortening, compared to purely isometric contractions performed at the same final lengths. We examined force, stiffness, and the 1,0 and 1,1 equatorial and M3 and M6 meridional reflections in skinned rabbit psoas bundles, at steady-state isometric contraction following active lengthening to a sarcomere length of 3.0 µm (15.4% initial bundle length at 7.7% bundle length/s), and active shortening to a sarcomere length
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5

Yamaguchi, H., M. Takaki, H. Matsubara, S. Yasuhara, and H. Suga. "Constancy and variability of contractile efficiency as a function of calcium and cross-bridge kinetics: simulation." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 4 (1996): H1501—H1508. http://dx.doi.org/10.1152/ajpheart.1996.270.4.h1501.

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We simulated myocardial Ca2+ (Ca) and cross-bridge (CB) kinetics to get insight into the experimentally observed constancy and variability of cardiac contractile efficiency in generating total mechanical energy under various inotropic and pathological conditions. The simulation consisted of a Ca transient, Ca association and dissociation rate constants of troponin C, and CB on and off rate constants. We evaluated sarcomere isometric twitch contractions at a constant muscle length. We assumed that each CB cycle hydrolyzes one ATP and that the force-length area (FLA) quantifies the total mechani
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6

Hai, C. M., and R. A. Murphy. "Cross-bridge dephosphorylation and relaxation of vascular smooth muscle." American Journal of Physiology-Cell Physiology 256, no. 2 (1989): C282—C287. http://dx.doi.org/10.1152/ajpcell.1989.256.2.c282.

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We tested the hypothesis that relaxation in vascular smooth muscle is the result of inactivation of myosin light chain kinase and cross-bridge dephosphorylation. Fast neurally mediated contractions of swine carotid medial strips were induced by electrical field stimulation. Termination of the stimulus resulted in relaxation with a half time of 2 min. Nifedipine (0.1 microM) increased the relaxation rate without significant effects on the contractile response. Cross-bridge dephosphorylation was much faster than stress decay with basal levels reached within 1 min when 73% of the developed stress
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7

Hellstrand, P., and I. Nordstrom. "Cross-bridge kinetics during shortening in early and sustained contraction of intestinal smooth muscle." American Journal of Physiology-Cell Physiology 265, no. 3 (1993): C695—C703. http://dx.doi.org/10.1152/ajpcell.1993.265.3.c695.

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Mechanisms responsible for the decrease in shortening velocity after prolonged contraction ("latch" state) were investigated at identical force during early (20 s, "phasic") and sustained (5 min, "tonic") phases of high-K+ (25-30 mM) contractions in smooth muscle of guinea pig taenia coli. Cytoplasmic Ca2+ concentration, myosin light-chain phosphorylation, and maximum shortening velocity all declined from 20 s to 5 min of contraction. The time course of shortening following isotonic quick release was biexponential, with a fastest rate constant of approximately 80 s-1 in both phasic and tonic c
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8

Janson, L. W., J. Kolega, and D. L. Taylor. "Modulation of contraction by gelation/solation in a reconstituted motile model." Journal of Cell Biology 114, no. 5 (1991): 1005–15. http://dx.doi.org/10.1083/jcb.114.5.1005.

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The actin-based cytoskeleton is a dynamic component of living cells with major structural and contractile properties involved in fundamental cellular processes. The action of actin-binding proteins can decrease or increase the gel structure. Changes in the actin-based cytoskeleton have long been thought to modulate the myosin II-based contractions involved in these cellular processes, but there has been some debate concerning whether maximal gelation increases or decreases contractile activity. To address this question, we have examined how contractile activity is modulated by the extent of ac
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9

Evans, E., A. Leung, and D. Zhelev. "Synchrony of cell spreading and contraction force as phagocytes engulf large pathogens." Journal of Cell Biology 122, no. 6 (1993): 1295–300. http://dx.doi.org/10.1083/jcb.122.6.1295.

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A simple micromechanical method has been used to directly measure the force of contraction in single mammalian phagocytes (blood granulocytes) during engulfment of large yeast pathogens. Both the time course of cell spreading over the yeast particle and increase in cell body contractile force were quantitated at three temperatures in the range of 23-35 degrees C. The surprising feature of the phagocyte response was that engulfment and cell body contraction occurred in a serial sequence: i.e., the phagocyte spread rapidly over the particle at a steady rate with no detectable cell body contracti
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10

Raiteri, Brent J., Andrew G. Cresswell, and Glen A. Lichtwark. "Three-dimensional geometrical changes of the human tibialis anterior muscle and its central aponeurosis measured with three-dimensional ultrasound during isometric contractions." PeerJ 4 (July 28, 2016): e2260. http://dx.doi.org/10.7717/peerj.2260.

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Background.Muscles not only shorten during contraction to perform mechanical work, but they also bulge radially because of the isovolumetric constraint on muscle fibres. Muscle bulging may have important implications for muscle performance, however quantifying three-dimensional (3D) muscle shape changes in human muscle is problematic because of difficulties with sustaining contractions for the duration of anin vivoscan. Although two-dimensional ultrasound imaging is useful for measuring local muscle deformations, assumptions must be made about global muscle shape changes, which could lead to e
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11

Smolock, Elaine M., Danielle M. Trappanese, Shaohua Chang, Tanchun Wang, Paul Titchenell, and Robert S. Moreland. "siRNA-mediated knockdown of h-caldesmon in vascular smooth muscle." American Journal of Physiology-Heart and Circulatory Physiology 297, no. 5 (2009): H1930—H1939. http://dx.doi.org/10.1152/ajpheart.00129.2009.

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Smooth muscle contraction involves phosphorylation of the regulatory myosin light chain. However, this thick-filament system of regulation cannot account for all aspects of a smooth muscle contraction. An alternate site of contractile regulation may be in the thin-filament-associated proteins, in particular caldesmon. Caldesmon has been proposed to be an inhibitory protein that acts either as a brake to stop any increase in resting or basal tone, or as a modulatory protein during contraction. The goal of this study was to use short interfering RNA technology to decrease the levels of the smoot
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12

Fenwick, Axel J., David C. Lin, and Bertrand C. W. Tanner. "Myosin cross-bridge kinetics slow at longer muscle lengths during isometric contractions in intact soleus from mice." Proceedings of the Royal Society B: Biological Sciences 288, no. 1950 (2021): 20202895. http://dx.doi.org/10.1098/rspb.2020.2895.

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Muscle contraction results from force-generating cross-bridge interactions between myosin and actin. Cross-bridge cycling kinetics underlie fundamental contractile properties, such as active force production and energy utilization. Factors that influence cross-bridge kinetics at the molecular level propagate through the sarcomeres, cells and tissue to modulate whole-muscle function. Conversely, movement and changes in the muscle length can influence cross-bridge kinetics on the molecular level. Reduced, single-molecule and single-fibre experiments have shown that increasing the strain on cross
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13

Igarashi, Y., Y. Goto, O. Yamada, T. Ishii, and H. Suga. "Transient vs. steady end-systolic pressure-volume relation in dog left ventricle." American Journal of Physiology-Heart and Circulatory Physiology 252, no. 5 (1987): H998—H1004. http://dx.doi.org/10.1152/ajpheart.1987.252.5.h998.

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We compared transient slope of end-systolic pressure-volume line (T-Emax) with steady Emax (S-Emax) in isolated cross-circulated canine left ventricles. T-Emax is the slope of the end-systolic pressure-volume line (ESPVL) determined from the last steady-state ejecting contraction (SEC) and the first transient isovolumic contraction produced by end-diastolic volume clamp. S-Emax is the slope of ESPVL determined from five steady-state contractions by linear regression analysis. We obtained three T-Emax values in the same contractile state by changing ejection fraction (EF) of SEC to three levels
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14

Lirio-Romero, Cristina, Rocío Palomo-Carrión, Helena Romay-Barrero, Asunción Ferri-Morales, Virginia Prieto-Gómez, and María Torres-Lacomba. "Age Differences in Motor Recruitment Patterns of the Shoulder in Dynamic and Isometric Contractions. A Cross-Sectional Study." Journal of Clinical Medicine 10, no. 3 (2021): 525. http://dx.doi.org/10.3390/jcm10030525.

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Aging processes in the musculoskeletal system lead to functional impairments that restrict participation. Purpose: To assess differences in the force and motor recruitment patterns of shoulder muscles between age groups to understand functional disorders. A cross-sectional study comparing 30 adults (20–64) and 30 older adults (>65). Surface electromyography (sEMG) of the middle deltoid, upper and lower trapezius, infraspinatus, and serratus anterior muscles was recorded. Maximum isometric voluntary contraction (MIVC) was determined at 45° glenohumeral abduction. For the sEMG signal registra
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15

Descovich, Carlos Patino, Daniel B. Cortes, Sean Ryan, et al. "Cross-linkers both drive and brake cytoskeletal remodeling and furrowing in cytokinesis." Molecular Biology of the Cell 29, no. 5 (2018): 622–31. http://dx.doi.org/10.1091/mbc.e17-06-0392.

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Cell shape changes such as cytokinesis are driven by the actomyosin contractile cytoskeleton. The molecular rearrangements that bring about contractility in nonmuscle cells are currently debated. Specifically, both filament sliding by myosin motors, as well as cytoskeletal cross-linking by myosins and nonmotor cross-linkers, are thought to promote contractility. Here we examined how the abundance of motor and nonmotor cross-linkers affects the speed of cytokinetic furrowing. We built a minimal model to simulate contractile dynamics in the Caenorhabditis elegans zygote cytokinetic ring. This mo
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16

Phillippe, M., and E. K. Chien. "Potassium chloride effects on the hormonal signal transduction mechanisms underlying phasic myometrial contractions." Journal of Endocrinology 146, no. 3 (1995): 485–93. http://dx.doi.org/10.1677/joe.0.1460485.

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Abstract These studies sought to test the hypothesis that potassium-stimulated phasic myometrial contractions utilize cytosolic calcium oscillation-like mechanisms comparable to those activated in response to oxytocin. Uterine tissue was obtained from pro-oestrus/oestrus Sprague-Dawley rats. In vitro isometric contraction studies were performed using longitudinal myometrial strips; computer digitalized contraction data were analyzed for contraction area, and normalized for tissue cross-section area. Dose–response studies were performed using potassium chloride with and without inhibitors of cy
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17

Janson, L. W., and D. L. Taylor. "In vitro models of tail contraction and cytoplasmic streaming in amoeboid cells." Journal of Cell Biology 123, no. 2 (1993): 345–56. http://dx.doi.org/10.1083/jcb.123.2.345.

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We have developed a reconstituted gel-sol and contractile model system that mimics the structure and dynamics found at the ectoplasm/endoplasm interface in the tails of many amoeboid cells. We tested the role of gel-sol transformations of the actin-based cytoskeleton in the regulation of contraction and in the generation of endoplasm from ectoplasm. In a model system with fully phosphorylated myosin II, we demonstrated that either decreasing the actin filament length distribution or decreasing the extent of actin filament cross-linking initiated both a weakening of the gel strength and contrac
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18

Petit, J., G. M. Filippi, M. Gioux, C. C. Hunt, and Y. Laporte. "Effects of tetanic contraction of motor units of similar type on the initial stiffness to ramp stretch of the cat peroneus longus muscle." Journal of Neurophysiology 64, no. 6 (1990): 1724–32. http://dx.doi.org/10.1152/jn.1990.64.6.1724.

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1. The stiffness during the initial portion of a ramp stretch was measured in cat peroneus longus muscle at rest and during maximal tetanic contractions produced by increasing numbers of motor units of the same type [slow (S), fast fatigue resistant (FR), or fast fatigable (FF)]. 2. This initial ramp stiffness was defined as the ratio between tension and length change over the limited range of constant velocity extension during which tension rose linearly with length change. This stiffness was reduced by tetanic contraction of a number of motor units while other units remained inactive. The re
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19

Zult, Tjerk, Stuart Goodall, Kevin Thomas, Tibor Hortobágyi, and Glyn Howatson. "Mirror illusion reduces motor cortical inhibition in the ipsilateral primary motor cortex during forceful unilateral muscle contractions." Journal of Neurophysiology 113, no. 7 (2015): 2262–70. http://dx.doi.org/10.1152/jn.00686.2014.

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Forceful, unilateral contractions modulate corticomotor paths targeting the resting, contralateral hand. However, it is unknown whether mirror-viewing of a slowly moving but forcefully contracting hand would additionally affect these paths. Here we examined corticospinal excitability and short-interval intracortical inhibition (SICI) of the right-ipsilateral primary motor cortex (M1) in healthy young adults under no-mirror and mirror conditions at rest and during right wrist flexion at 60% maximal voluntary contraction (MVC). During the no-mirror conditions neither hand was visible, whereas in
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20

Walsh, Michael P., Jacquelyn E. Andrea, Bruce G. Allen, Odile Clément-Chomienne, Elizabeth M. Collins, and Kathleen G. Morgan. "Smooth muscle protein kinase C." Canadian Journal of Physiology and Pharmacology 72, no. 11 (1994): 1392–99. http://dx.doi.org/10.1139/y94-201.

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Protein kinase C (PKC) was first implicated in the regulation of smooth muscle contraction with the observation that phorbol esters induce slowly developing, sustained contractions. In some vascular smooth muscles, e.g., ferret aorta, phorbol ester induced contractions occur without an increase in sarcoplasmic free-Ca2+ concentration ([Ca]i) or myosin light chain phosphorylation. This response appears to be mediated by a Ca2+-independent isoenzyme of PKC (probably PKCε), since saponin-permeabilized single ferret aortic smooth muscle cells, which retain receptor coupling, developed force in res
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21

Taylor, Chloe E., Daniel Boulton, Erin J. Howden, Christoph Siebenmann, and Vaughan G. Macefield. "Central command increases muscle sympathetic nerve activity more to contracting than noncontracting muscle during rhythmic isotonic leg exercise." Journal of Neurophysiology 121, no. 5 (2019): 1704–10. http://dx.doi.org/10.1152/jn.00075.2019.

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We have previously shown that the increase in muscle sympathetic nerve activity (MSNA) to contracting muscle during sustained isometric exercise is due primarily to central command and that contracting muscle does not express a metaboreceptor-driven increase in MSNA. Here we tested the hypothesis that MSNA increases to the contracting muscle also during rhythmic isotonic exercise, in which muscle metabolites will not accumulate because the contraction is performed without external load. MSNA was recorded from the common peroneal nerve in 10 participants, and negative-going sympathetic spikes w
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22

Strehlow, Brian W., Damien Jorgensen, Nicole S. Webster, Mari-Carmen Pineda, and Alan Duckworth. "Using a thermistor flowmeter with attached video camera for monitoring sponge excurrent speed and oscular behaviour." PeerJ 4 (December 13, 2016): e2761. http://dx.doi.org/10.7717/peerj.2761.

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A digital, four-channel thermistor flowmeter integrated with time-lapse cameras was developed as an experimental tool for measuring pumping rates in marine sponges, particularly those with small excurrent openings (oscula). Combining flowmeters with time-lapse imagery yielded valuable insights into the contractile behaviour of oscula inCliona orientalis. Osculum cross-sectional area (OSA) was positively correlated to measured excurrent speeds (ES), indicating that sponge pumping and osculum contraction are coordinated behaviours. Both OSA and ES were positively correlated to pumping rate (Q).
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23

Westerhof, Nico, Christa Boer, Regis R. Lamberts, and Pieter Sipkema. "Cross-Talk Between Cardiac Muscle and Coronary Vasculature." Physiological Reviews 86, no. 4 (2006): 1263–308. http://dx.doi.org/10.1152/physrev.00029.2005.

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The cardiac muscle and the coronary vasculature are in close proximity to each other, and a two-way interaction, called cross-talk, exists. Here we focus on the mechanical aspects of cross-talk including the role of the extracellular matrix. Cardiac muscle affects the coronary vasculature. In diastole, the effect of the cardiac muscle on the coronary vasculature depends on the (changes in) muscle length but appears to be small. In systole, coronary artery inflow is impeded, or even reversed, and venous outflow is augmented. These systolic effects are explained by two mechanisms. The waterfall
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24

Zhang, Shi-Jin, Daniel C. Andersson, Marie E. Sandström, Håkan Westerblad, and Abram Katz. "Cross bridges account for only 20% of total ATP consumption during submaximal isometric contraction in mouse fast-twitch skeletal muscle." American Journal of Physiology-Cell Physiology 291, no. 1 (2006): C147—C154. http://dx.doi.org/10.1152/ajpcell.00578.2005.

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It is generally believed that cross bridges account for >50% of the total ATP consumed by skeletal muscle during contraction. We investigated the effect of N-benzyl- p-toluene sulfonamide (BTS), an inhibitor of myosin ATPase, on muscle force production and energy metabolism under near-physiological conditions (50-Hz stimulation frequency at 30°C results in 35% of maximal force). Extensor digitorum longus muscles from mice were isolated and stimulated to perform continuous isometric tetanic contractions. Metabolites of energy metabolism were analyzed with fluorometric techniques. ATP turnove
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25

Walsh, Michael P., Odile Clément-Chomienne, Jacquelyn E. Andrea, Bruce G. Allen, Arie Horowitz, and Kathleen G. Morgan. "Protein kinase C mediation of Ca2+-independent contractions of vascular smooth muscle." Biochemistry and Cell Biology 74, no. 4 (1996): 485–502. http://dx.doi.org/10.1139/o96-053.

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Tumour-promoting phorbol esters induce slow, sustained contractions of vascular smooth muscle, suggesting that protein kinase C (PKC) may play a role in the regulation of smooth muscle contractility. In some cases, e.g., ferret aortic smooth muscle, phorbol ester induced contractions occur without a change in [Ca2+]i or myosin phosphorylation. Direct evidence for the involvement of PKC came from the use of single saponin-permeabilized ferret aortic cells. A constitutively active catalytic fragment of PKC induced a slow, sustained contraction similar to that triggered by phenylephrine. Both res
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26

Koh, Timothy J., and Susan V. Brooks. "Lengthening contractions are not required to induce protection from contraction-induced muscle injury." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281, no. 1 (2001): R155—R161. http://dx.doi.org/10.1152/ajpregu.2001.281.1.r155.

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We tested the hypothesis that lengthening contractions and subsequent muscle fiber degeneration and/or regeneration are required to induce exercise-associated protection from lengthening contraction-induced muscle injury. Extensor digitorum longus muscles in anesthetized mice were exposed in situ to repeated lengthening contractions, isometric contractions, or passive stretches. Three days after lengthening contractions, maximum isometric force production was decreased by 55%, and muscle cross sections contained a significant percentage (18%) of injured fibers. Neither isometric contractions n
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27

Zhao, Fuqiang, Yue Zhao, Xiaojun Zhao, et al. "Numerical Study on the Influence of Variable Section-Enhanced Mass Transfer Flow Field Design on PEMFC Performance Based on Underrib Convection Flow." International Journal of Energy Research 2023 (September 20, 2023): 1–34. http://dx.doi.org/10.1155/2023/5327387.

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The optimal design of variable section is a flow field optimization method that changes the pressure of the reacting gas in the flow channel by setting up a contraction surface in the flow channel, which is effective in improving many aspects of the proton exchange membrane fuel cell (PEMFC) performance. However, there are also problems such as uneven oxygen distribution in some of the flow channels, and the current density and net output power are not significantly improved. To find a balance among gas transfer efficiency, drainage capacity, uniformity of current density distribution, and out
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28

Krueger, Daniel, Theresa Quinkler, Simon Arnold Mortensen, Carsten Sachse, and Stefano De Renzis. "Cross-linker–mediated regulation of actin network organization controls tissue morphogenesis." Journal of Cell Biology 218, no. 8 (2019): 2743–61. http://dx.doi.org/10.1083/jcb.201811127.

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Contraction of cortical actomyosin networks driven by myosin activation controls cell shape changes and tissue morphogenesis during animal development. In vitro studies suggest that contractility also depends on the geometrical organization of actin filaments. Here we analyze the function of actomyosin network topology in vivo using optogenetic stimulation of myosin-II in Drosophila embryos. We show that early during cellularization, hexagonally arrayed actomyosin fibers are resilient to myosin-II activation. Actomyosin fibers then acquire a ring-like conformation and become contractile and se
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29

Popping, S., S. Mruck, Y. Fischer, et al. "Economy of contraction of cardiomyocytes as influenced by different positive inotropic interventions." American Journal of Physiology-Heart and Circulatory Physiology 271, no. 1 (1996): H357—H364. http://dx.doi.org/10.1152/ajpheart.1996.271.1.h357.

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In the present study the effects of the novel cardiotonic agent EMD-57033 on contraction and energetic demand of isolated, electrically stimulated cardiomyocytes were investigated and compared with the effects of enhancement of extracellular calcium and of the beta-mimetic isoproterenol. In a specially designed setup [H. Rose, K.H. Strotmann, S. Popping, Y. Fischer, D. Kulsch, and H. Kammermeier. Am. J. Physiol. 261 (Heart Circ. Physiol. 30): H1329-H1334, 1991] parameters of contractile behavior and metabolic demand (O2 consumption) of isolated cardiac myocytes were measured. For a given enhan
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30

Hai, Chi-Ming, and Hak Rim Kim. "An expanded latch-bridge model of protein kinase C-mediated smooth muscle contraction." Journal of Applied Physiology 98, no. 4 (2005): 1356–65. http://dx.doi.org/10.1152/japplphysiol.00834.2004.

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A thin-filament-regulated latch-bridge model of smooth muscle contraction is proposed to integrate thin-filament-based inhibition of actomyosin ATPase activity with myosin phosphorylation in the regulation of smooth muscle mechanics. The model included two latch-bridge cycles, one of which was identical to the four-state model as proposed by Hai and Murphy ( Am J Physiol Cell Physiol 255: C86–C94, 1988), whereas the ultraslow cross-bridge cycle has lower cross-bridge cycling rates. The model-fitted phorbol ester induced slow contractions at constant myosin phosphorylation and predicted steeper
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31

Sawada, Thais Naomi, Adriana Claudia Lunardi, Daniela Fantin Carro, Débora Françoes Porto, Leda Tomiko Yamada da Silveira, and Elizabeth Alves Gonçalves Ferreira. "Two devices to facilitate the perception of pelvic floor muscle contraction in the sitting position in women with urinary incontinence: comparative analysis." Fisioterapia e Pesquisa 29, no. 3 (2022): 270–77. http://dx.doi.org/10.1590/1809-2950/22009229032022en.

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ABSTRACT The use of support devices may facilitate the perception of pelvic floor muscle (PFM) contraction, which is difficult to be performed. Therefore, this study aimed to compare the perception of PFM contraction in the sitting position during the use of two different support devices on women with PFM dysfunction. This is a cross-sectional study performed with 37 women with stress or mixed urinary incontinence (UI). All women performed three free PFM contractions sitting on a chair, followed by three contractions using each support device (sand pads and a cylindrical foam, which provide sc
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32

Taylor, T. W., Y. Goto, and H. Suga. "Variable cross-bridge cycling-ATP coupling accounts for cardiac mechanoenergetics." American Journal of Physiology-Heart and Circulatory Physiology 264, no. 3 (1993): H994—H1004. http://dx.doi.org/10.1152/ajpheart.1993.264.3.h994.

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Cardiac twitch contractions were simulated by Huxley's sliding filament cross-bridge muscle model coupled with parallel and series elastic components. The energetics of the contraction were based on the ATP hydrolysis for the cross-bridge cycling. Force-length area (FLA), as a measure of the total mechanical energy, was computed for both isometric and isotonic contractions in a manner similar to the pressure-volume area (PVA) (Suga, H. Physiol. Rev. 70: 247–277, 1990). PVA correlates linearly with cardiac oxygen consumption, and since FLA is analogous to PVA, FLA should correlate with the ATP
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33

Nicosia, Mark A., James G. Brasseur, Ji-Bin Liu, and Larry S. Miller. "Local longitudinal muscle shortening of the human esophagus from high-frequency ultrasonography." American Journal of Physiology-Gastrointestinal and Liver Physiology 281, no. 4 (2001): G1022—G1033. http://dx.doi.org/10.1152/ajpgi.2001.281.4.g1022.

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We analyzed local longitudinal shortening by combining concurrent ultrasonography and manometry with basic principles of mechanics. We applied the law of mass conservation to quantify local axial shortening of the esophageal wall from ultrasonically measured cross-sectional area concurrently with measured intraluminal pressure, from which correlations between local contraction of longitudinal and circular muscle are inferred. Two clear phases of local longitudinal shortening were observed during bolus transport. During luminal filling by bolus fluid, the muscle layer distends and the muscle th
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34

Ratz, Paul H., and John E. Speich. "Evidence that actomyosin cross bridges contribute to “passive” tension in detrusor smooth muscle." American Journal of Physiology-Renal Physiology 298, no. 6 (2010): F1424—F1435. http://dx.doi.org/10.1152/ajprenal.00635.2009.

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Contraction of detrusor smooth muscle (DSM) at short muscle lengths generates a stiffness component we termed adjustable passive stiffness (APS) that is retained in tissues incubated in a Ca2+-free solution, shifts the DSM length-passive tension curve up and to the left, and is softened by muscle strain and release (strain softened). In the present study, we tested the hypothesis that APS is due to slowly cycling actomyosin cross bridges. APS and active tension produced by the stimulus, KCl, displayed similar length dependencies with identical optimum length values. The myosin II inhibitor ble
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35

Murphy, Richard A., and Christopher M. Rembold. "The latch-bridge hypothesis of smooth muscle contraction." Canadian Journal of Physiology and Pharmacology 83, no. 10 (2005): 857–64. http://dx.doi.org/10.1139/y05-090.

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In contrast to striated muscle, both normalized force and shortening velocities are regulated functions of cross-bridge phosphorylation in smooth muscle. Physiologically this is manifested as relatively fast rates of contraction associated with transiently high levels of cross-bridge phosphorylation. In sustained contractions, Ca2+, cross-bridge phosphorylation, and ATP consumption rates fall, a phenomenon termed "latch". This review focuses on the Hai and Murphy (1988a) model that predicted the highly non-linear dependence of force on phosphorylation and a directly proportional dependence of
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36

Yoshinaga, Natsuhiko, and Philippe Marcq. "Contraction of cross-linked actomyosin bundles." Physical Biology 9, no. 4 (2012): 046004. http://dx.doi.org/10.1088/1478-3975/9/4/046004.

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37

Iribaram, Wempi Geovano, and Vina N. Van Harling. "Pengaruh Perbedaan Ukuran Intake Kontraksi Terhadap Laju Aliran Di Ruang Uji." Jurnal Teknik Mesin 16, no. 2 (2023): 189–93. http://dx.doi.org/10.30630/jtm.16.2.1132.

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The contraction cone or intake is a very important part of wind tunnel design because it has a high impact on the quality of airflow in the test section. The design of the contraction cone aims to create the air pressure required at the time of entry of the test section without experiencing much turbulence. This research was conducted using an experimental method, where in this study it was carried out by testing, making 3 intake components or funnels of different sizes. The calculation results obtained funnel 1 contraction with a value of 11,466 m3 / s, funnel 2 contraction with a value of 12
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38

Somlyo, Andrew P., and Avril V. Somlyo. "Smooth Muscle: Excitation-Contraction Coupling, Contractile Regulation, and the Cross-Bridge Cycle." Alcoholism: Clinical and Experimental Research 18, no. 1 (1994): 138–43. http://dx.doi.org/10.1111/j.1530-0277.1994.tb00893.x.

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39

Bursztyn, Limor, Osnat Eytan, Ariel J. Jaffa, and David Elad. "Mathematical model of excitation-contraction in a uterine smooth muscle cell." American Journal of Physiology-Cell Physiology 292, no. 5 (2007): C1816—C1829. http://dx.doi.org/10.1152/ajpcell.00478.2006.

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Uterine contractility is generated by contractions of myometrial smooth muscle cells (SMCs) that compose most of the myometrial layer of the uterine wall. Calcium ion (Ca2+) entry into the cell can be initiated by depolarization of the cell membrane. The increase in the free Ca2+ concentration within the cell initiates a chain of reactions, which lead to formation of cross bridges between actin and myosin filaments, and thereby the cell contracts. During contraction the SMC shortens while it exerts forces on neighboring cells. A mathematical model of myometrial SMC contraction has been develop
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40

Chen, Jackey, Daniel Hahn, and Geoffrey A. Power. "Shortening-induced residual force depression in humans." Journal of Applied Physiology 126, no. 4 (2019): 1066–73. http://dx.doi.org/10.1152/japplphysiol.00931.2018.

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When an isometric muscle contraction is immediately preceded by an active shortening contraction, a reduction in steady-state isometric force is observed relative to an isometric reference contraction at the same muscle length and level of activation. This shortening-induced reduction in isometric force, termed “residual force depression” (rFD), has been under investigation for over a half century. Various experimental models have revealed the positive relationship between rFD and the force and displacement performed during shortening, with rFD values ranging from 5 to 39% across various muscl
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41

Welsh, Denise C., Konstantina Dipla, Patrick H. McNulty, et al. "Preserved contractile function despite atrophic remodeling in unloaded rat hearts." American Journal of Physiology-Heart and Circulatory Physiology 281, no. 3 (2001): H1131—H1136. http://dx.doi.org/10.1152/ajpheart.2001.281.3.h1131.

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The present study was designed to determine whether myocardial atrophy is necessarily associated with changes in cardiac contractility. Myocardial unloading of normal hearts was produced via heterotopic transplantation in rats. Contractions of isolated myocytes (1.2 mM Ca2+; 37°C) were assessed during field stimulation (0.5, 1.0, and 2.0 Hz), and papillary muscle contractions were assessed during direct stimulation (2.0 mM Ca2+; 37°C; 0.5 Hz). Hemodynamic unloading was associated with a 41% decrease in median myocyte volume and proportional decreases in myocyte length and width. Nevertheless,
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42

Dongaonkar, Ranjeet M., Randolph H. Stewart, Glen A. Laine, Michael J. Davis, David C. Zawieja, and Christopher M. Quick. "Venomotion modulates lymphatic pumping in the bat wing." American Journal of Physiology-Heart and Circulatory Physiology 296, no. 6 (2009): H2015—H2021. http://dx.doi.org/10.1152/ajpheart.00418.2008.

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In skin, it is believed that lymph must be pumped by intrinsic contraction of lymphatic muscle, since investigators have not considered that cyclical dilation of venules could compress adjacent lymphatic microvessels. Because lymphatic vessels are sensitive to stretch, we hypothesized that venomotion not only can cause extrinsic pumping of lymph in nearby lymphatic vessels, but also can stimulate intrinsic contractions. Bat wing venules have pronounced venomotion and are in close proximity to lymphatic microvessels, and can be studied noninvasively without the confounding effects of anesthesia
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43

Yu, S. N., P. E. Crago, and H. J. Chiel. "A nonisometric kinetic model for smooth muscle." American Journal of Physiology-Cell Physiology 272, no. 3 (1997): C1025—C1039. http://dx.doi.org/10.1152/ajpcell.1997.272.3.c1025.

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We have modeled the nonisometric contractile dynamics of smooth muscle by modifying a four-state model of actin and myosin bonds originally proposed by Hai and Murphy to simulate the isometric contractions of vertebrate smooth muscle. The model includes a latch bridge, which cycles more slowly than regular cross bridges. We generalized this model to represent the calcium-regulated processes of vertebrate and invertebrate smooth muscles. We added length dynamics by assuming length-dependent bonding and unbonding rates for the cross bridges. The calculation of the cross-bridge length distributio
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44

Sundberg, Christopher W., Andrew Kuplic, Hamidollah Hassanlouei, and Sandra K. Hunter. "Mechanisms for the age-related increase in fatigability of the knee extensors in old and very old adults." Journal of Applied Physiology 125, no. 1 (2018): 146–58. http://dx.doi.org/10.1152/japplphysiol.01141.2017.

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The mechanisms for the age-related increase in fatigability during high-velocity contractions in old and very old adults (≥80 yr) are unresolved. Moreover, whether the increased fatigability with advancing age and the underlying mechanisms differ between men and women is not known. The purpose of this study was to quantify the fatigability of knee extensor muscles and identify the mechanisms of fatigue in 30 young (22.6 ± 0.4 yr; 15 men), 62 old (70.5 ± 0.7 yr; 33 men), and 12 very old (86.0 ± 1.3 yr; 6 men) men and women elicited by high-velocity concentric contractions. Participants performe
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45

Mullins, Paula D., та Vladimir E. Bondarenko. "Mathematical model for β1-adrenergic regulation of the mouse ventricular myocyte contraction". American Journal of Physiology-Heart and Circulatory Physiology 318, № 2 (2020): H264—H282. http://dx.doi.org/10.1152/ajpheart.00492.2019.

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The β1-adrenergic regulation of cardiac myocyte contraction plays an important role in regulating heart function. Activation of this system leads to an increased heart rate and stronger myocyte contraction. However, chronic stimulation of the β1-adrenergic signaling system can lead to cardiac hypertrophy and heart failure. To understand the mechanisms of action of β1-adrenoceptors, a mathematical model of cardiac myocyte contraction that includes the β1-adrenergic system was developed and studied. The model was able to simulate major experimental protocols for measurements of steady-state forc
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46

Andrushko, Justin W., Joel L. Lanovaz, Kelsey M. Björkman, Saija A. Kontulainen, and Jonathan P. Farthing. "Unilateral strength training leads to muscle-specific sparing effects during opposite homologous limb immobilization." Journal of Applied Physiology 124, no. 4 (2018): 866–76. http://dx.doi.org/10.1152/japplphysiol.00971.2017.

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Cross education (CE) occurs after unilateral training whereby performance of the untrained contralateral limb is enhanced. A few studies have shown that CE can preserve or “spare” strength and size of an opposite immobilized limb, but the specificity (i.e., trained homologous muscle and contraction type) of these effects is unknown. The purpose was to investigate specificity of CE “sparing” effects with immobilization. The nondominant forearm of 16 participants was immobilized with a cast, and participants were randomly assigned to a resistance training (eccentric wrist flexion, 3 times/week)
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47

Dongaonkar, Ranjeet M., Randolph H. Stewart, Glen A. Laine, Michael J. Davis, David C. Zawieja, and Christopher M. Quick. "Venomotion modulates lymphatic pumping in the bat wing." American Journal of Physiology-Heart and Circulatory Physiology 296, no. 6 (2009): H2015—H2021. https://doi.org/10.5281/zenodo.13459558.

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(Uploaded by Plazi for the Bat Literature Project) In skin, it is believed that lymph must be pumped by intrinsic contraction of lymphatic muscle, since investigators have not considered that cyclical dilation of venules could compress adjacent lymphatic microvessels. Because lymphatic vessels are sensitive to stretch, we hypothesized that venomotion not only can cause extrinsic pumping of lymph in nearby lymphatic vessels, but also can stimulate intrinsic contractions. Bat wing venules have pronounced venomotion and are in close proximity to lymphatic microvessels, and can be studied noninvas
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48

Dongaonkar, Ranjeet M., Randolph H. Stewart, Glen A. Laine, Michael J. Davis, David C. Zawieja, and Christopher M. Quick. "Venomotion modulates lymphatic pumping in the bat wing." American Journal of Physiology-Heart and Circulatory Physiology 296, no. 6 (2009): H2015—H2021. https://doi.org/10.5281/zenodo.13459558.

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Abstract:
(Uploaded by Plazi for the Bat Literature Project) In skin, it is believed that lymph must be pumped by intrinsic contraction of lymphatic muscle, since investigators have not considered that cyclical dilation of venules could compress adjacent lymphatic microvessels. Because lymphatic vessels are sensitive to stretch, we hypothesized that venomotion not only can cause extrinsic pumping of lymph in nearby lymphatic vessels, but also can stimulate intrinsic contractions. Bat wing venules have pronounced venomotion and are in close proximity to lymphatic microvessels, and can be studied noninvas
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49

Dongaonkar, Ranjeet M., Randolph H. Stewart, Glen A. Laine, Michael J. Davis, David C. Zawieja, and Christopher M. Quick. "Venomotion modulates lymphatic pumping in the bat wing." American Journal of Physiology-Heart and Circulatory Physiology 296, no. 6 (2009): H2015—H2021. https://doi.org/10.5281/zenodo.13459558.

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Abstract:
(Uploaded by Plazi for the Bat Literature Project) In skin, it is believed that lymph must be pumped by intrinsic contraction of lymphatic muscle, since investigators have not considered that cyclical dilation of venules could compress adjacent lymphatic microvessels. Because lymphatic vessels are sensitive to stretch, we hypothesized that venomotion not only can cause extrinsic pumping of lymph in nearby lymphatic vessels, but also can stimulate intrinsic contractions. Bat wing venules have pronounced venomotion and are in close proximity to lymphatic microvessels, and can be studied noninvas
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50

Dongaonkar, Ranjeet M., Randolph H. Stewart, Glen A. Laine, Michael J. Davis, David C. Zawieja, and Christopher M. Quick. "Venomotion modulates lymphatic pumping in the bat wing." American Journal of Physiology-Heart and Circulatory Physiology 296, no. 6 (2009): H2015—H2021. https://doi.org/10.5281/zenodo.13459558.

Full text
Abstract:
(Uploaded by Plazi for the Bat Literature Project) In skin, it is believed that lymph must be pumped by intrinsic contraction of lymphatic muscle, since investigators have not considered that cyclical dilation of venules could compress adjacent lymphatic microvessels. Because lymphatic vessels are sensitive to stretch, we hypothesized that venomotion not only can cause extrinsic pumping of lymph in nearby lymphatic vessels, but also can stimulate intrinsic contractions. Bat wing venules have pronounced venomotion and are in close proximity to lymphatic microvessels, and can be studied noninvas
APA, Harvard, Vancouver, ISO, and other styles
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