Journal of Applied Physiology, Vol 44, Issue 1 85-89, Copyright © 1978 by American Physiological Society

ARTICLES

Adaptation of the rat myocardium to endurance training

G. Tibbits, B. J. Koziol, N. K. Roberts, K. M. Baldwin and R. J. Barnard

The purpose of this study was to assess cardiac adaptation to endurance training in rats. After 11 wk of progressive treadmill exercise (1 h/day), gastrocnemius cytochrome c oxidase activity was 38% higher (P less than 0.01) in the trained (n = 20) as compared to control (n = 20) rats. Cardiac Mg2+-stimulated myofibril ATPase activity (0.308 +/- 0.012 vs. 0.324 +/- 0.006 micrometer.mg-1.min-1) did not change nor was there any change in myofibril protein concentration (60.0 +/- 1.12 vs. 59.9 +/- 0.85 mg.g-1). The isolated left ventricular papillary muscle showed no significant change in time-to-peak tension (TPT) or half-relaxation time. Tension output, however, was significantly increased with training, 2.2 +/- 0.3 vs. 1.5 +/- 0.1 g.mm-2 (P less than 0.025). Furthermore, when the papillary preparations were perfused with 0.5 mM lanthanum (La3+) to displace membrane-bound Ca2+, the time course for tension decay was significantly prolonged in the trained muscles (P less than 0.001). We conclude that endurance running of this type does not necessarily increase myofibril ATPase activity or the time course of the isometric twitch of rat papillary muscle. However, tension output per unit area does increase and this appears to be due to a greater amount of Ca2+ being made available to the contractile apparatus.

This article has been cited by other articles:

				S. P. Harris, E. Rostkova, M. Gautel, and R. L. Moss Binding of Myosin Binding Protein-C to Myosin Subfragment S2 Affects Contractility Independent of a Tether Mechanism Circ. Res., October 29, 2004; 95(9): 930 - 936. [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. Machida, H. Tsujimoto, H. Suzuki, N. Kasuga, K. Kobayashi, and M. Narusawa Age-Related Differences in the Effect of Running Training on Cardiac Myosin Isozyme Composition in Rats J. Gerontol. A Biol. Sci. Med. Sci., September 1, 2002; 57(9): B339 - 343. [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]

				D. L. Allen, B. C. Harrison, A. Maass, M. L. Bell, W. C. Byrnes, and L. A. Leinwand Cardiac and skeletal muscle adaptations to voluntary wheel running in the mouse J Appl Physiol, May 1, 2001; 90(5): 1900 - 1908. [Abstract] [Full Text] [PDF]

				U. Wisloff, J. Helgerud, O. J. Kemi, and O. Ellingsen Intensity-controlled treadmill running in rats: {V}O2 max and cardiac hypertrophy Am J Physiol Heart Circ Physiol, March 1, 2001; 280(3): H1301 - H1310. [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]

				G. Tibbits, T Nagatomo, M Sasaki, and R. Barnard Cardiac sarcolemma: compositional adaptation to exercise Science, September 11, 1981; 213(4513): 1271 - 1273. [Abstract] [PDF]

				L. Lu, D. F. Mei, A.-G. Gu, S. Wang, B. Lentzner, D. E. Gutstein, D. Zwas, S. Homma, G.-H. Yi, and J. Wang Exercise training normalizes altered calcium-handling proteins during development of heart failure J Appl Physiol, April 1, 2002; 92(4): 1524 - 1530. [Abstract] [Full Text] [PDF]