Journal of Applied Physiology, Vol 73, Issue 4 1441-1448, Copyright © 1992 by American Physiological Society

ARTICLES

Effect of exercise training on intracellular free Ca2+ transients in ventricular myocytes of rats

M. H. Laughlin, M. E. Schaefer and M. Sturek
Department of Veterinary Biomedical Sciences, University of Missouri, Columbia 65211.

The purpose of this study was to test the hypothesis that exercise training induces enhanced intracellular free Ca2+ (Cai) availability to the contractile elements of cardiac cells. Cai transients were directly measured in single isolated contracting ventricular myocytes from exercise-trained (EX) and sedentary control (SED) rats. Male Sprague-Dawley rats underwent 16 wk of progressive treadmill exercise (32 m/min, 8% grade, 1.5 h/day) (EX) or were cage confined (SED). EX rats had lower resting heart rate and elevated skeletal muscle oxidative capacity. Cai was measured with the fluorescent Cai indicator fura-2. Simultaneous video monitoring indicated that myocytes suspended in physiological salt solution were quiescent until stimulated electrically at a frequency of 0.2 Hz (12-36 V, 2-ms duration). Stimulated Cai transients, measured from changes in fura-2 fluorescence, were similar in cells from EX and SED groups. Peak shortening, time to peak shortening, velocity of shortening, contraction duration, and time to half-relaxation were also similar in cells from EX and SED rats. Ryanodine (10 microM) was applied to eliminate the contribution of Ca2+ release from sarcoplasmic reticulum to the Cai transient. Verapamil was applied to eliminate the contribution of voltage-gated Ca2+ channels to Cai transients. Cai transients were also similar in cells from EX and SED groups after these pharmacological interventions. These results suggest that treadmill training of rats does not alter Cai availability to the contractile elements in isolated ventricular myocytes.

This article has been cited by other articles:

				Q. Jiao, Y. Bai, T. Akaike, H. Takeshima, Y. Ishikawa, and S. Minamisawa Sarcalumenin is essential for maintaining cardiac function during endurance exercise training Am J Physiol Heart Circ Physiol, August 1, 2009; 297(2): H576 - H582. [Abstract] [Full Text] [PDF]

				C.-H. Shao, X. H. T. Wehrens, T. A. Wyatt, S. Parbhu, G. J. Rozanski, K. P. Patel, and K. R. Bidasee Exercise training during diabetes attenuates cardiac ryanodine receptor dysregulation J Appl Physiol, April 1, 2009; 106(4): 1280 - 1292. [Abstract] [Full Text] [PDF]

				O. Cazorla, Y. Ait Mou, L. Goret, G. Vassort, M. Dauzat, A. Lacampagne, S. Tanguy, and P. Obert Effects of high-altitude exercise training on contractile function of rat skinned cardiomyocyte Cardiovasc Res, September 1, 2006; 71(4): 652 - 660. [Abstract] [Full Text] [PDF]

				B. M. Palmer, E. A. Mokelke, A. M. Thayer, and R. L. Moore Mild renal hypertension alters run training effects on the frequency response of rat cardiomyocyte mechanics J Appl Physiol, November 1, 2003; 95(5): 1799 - 1807. [Abstract] [Full Text] [PDF]

				G. M. Diffee and D. F. Nagle Regional differences in effects of exercise training on contractile and biochemical properties of rat cardiac myocytes J Appl Physiol, July 1, 2003; 95(1): 35 - 42. [Abstract] [Full Text] [PDF]

				S. Terada, I. Muraoka, and I. Tabata Changes in [Ca2+]i induced by several glucose transport-enhancing stimuli in rat epitrochlearis muscle J Appl Physiol, May 1, 2003; 94(5): 1813 - 1820. [Abstract] [Full Text] [PDF]

				G. M. Diffee and E. Chung Altered single cell force-velocity and power properties in exercise-trained rat myocardium J Appl Physiol, May 1, 2003; 94(5): 1941 - 1948. [Abstract] [Full Text] [PDF]

				X.-Q. Zhang, J. Song, L. L. Carl, W. Shi, A. Qureshi, Q. Tian, and J. Y. Cheung Effects of sprint training on contractility and [Ca2+]i transients in adult rat myocytes J Appl Physiol, October 1, 2002; 93(4): 1310 - 1317. [Abstract] [Full Text] [PDF]

				A J Natali, L A Wilson, M Peckham, D L Turner, S M Harrison, and E White Different regional effects of voluntary exercise on the mechanical and electrical properties of rat ventricular myocytes J. Physiol., June 15, 2002; 541(3): 863 - 875. [Abstract] [Full Text] [PDF]

				U. Wisloff, J. P. Loennechen, S. Currie, G. L. Smith, and O. Ellingsen Aerobic exercise reduces cardiomyocyte hypertrophy and increases contractility, Ca2+ sensitivity and SERCA-2 in rat after myocardial infarction Cardiovasc Res, April 1, 2002; 54(1): 162 - 174. [Abstract] [Full Text] [PDF]

				J. J Jones, N. J Dietz, C. L Heaps, J. L Parker, and M. Sturek Calcium buffering in coronary smooth muscle after chronic occlusion and exercise training Cardiovasc Res, August 1, 2001; 51(2): 359 - 367. [Abstract] [Full Text] [PDF]

				G. M. Diffee, E. A. Seversen, and M. M. Titus Exercise training increases the Ca2+ sensitivity of tension in rat cardiac myocytes J Appl Physiol, July 1, 2001; 91(1): 309 - 315. [Abstract] [Full Text] [PDF]

				B. M. Palmer, J. M. Lynch, S. M. Snyder, and R. L. Moore Renal hypertension prevents run training modification of cardiomyocyte diastolic Ca2+ regulation in male rats J Appl Physiol, June 1, 2001; 90(6): 2063 - 2069. [Abstract] [Full Text] [PDF]

				U. Wisloff, J. P. Loennechen, G. Falck, V. Beisvag, S. Currie, G. Smith, and O. Ellingsen Increased contractility and calcium sensitivity in cardiac myocytes isolated from endurance trained rats Cardiovasc Res, June 1, 2001; 50(3): 495 - 508. [Abstract] [Full Text] [PDF]

				A. Natali, D. Turner, S. Harrison, and E White Regional effects of voluntary exercise on cell size and contraction-frequency responses in rat cardiac myocytes J. Exp. Biol., January 3, 2001; 204(6): 1191 - 1199. [Abstract] [PDF]

				B. M. Palmer, M. C. Olsson, J. M. Lynch, L. C. Mace, S. M. Snyder, S. Valent, and R. L. Moore Chronic run training suppresses alpha -adrenergic response of rat cardiomyocytes and isovolumic left ventricle Am J Physiol Heart Circ Physiol, December 1, 1999; 277(6): H2136 - H2144. [Abstract] [Full Text] [PDF]

				B. M. Palmer, J. M. Lynch, S. M. Snyder, and R. L. Moore Effects of chronic run training on Na+-dependent Ca2+ efflux from rat left ventricular myocytes J Appl Physiol, February 1, 1999; 86(2): 584 - 591. [Abstract] [Full Text] [PDF]

				B. M. Palmer, A. M. Thayer, S. M. Snyder, and R. L. Moore Shortening and [Ca2+] dynamics of left ventricular myocytes isolated from exercise-trained rats J Appl Physiol, December 1, 1998; 85(6): 2159 - 2168. [Abstract] [Full Text] [PDF]

				X.-Q. Zhang, Y.-C. Ng, T. I. Musch, R. L. Moore, R. Zelis, and J. Y. Cheung Sprint training attenuates myocyte hypertrophy and improves Ca2+ homeostasis in postinfarction myocytes J Appl Physiol, February 1, 1998; 84(2): 544 - 552. [Abstract] [Full Text] [PDF]

				S. L. Rigby, P. A. Hofmann, J. Zhong, H. R. Adams, and L. J. Rubin Endotoxemia-induced myocardial dysfunction is not associated with changes in myofilament Ca2+ responsiveness Am J Physiol Heart Circ Physiol, February 1, 1998; 274(2): H580 - H590. [Abstract] [Full Text] [PDF]