Journal of Applied Physiology, Vol 79, Issue 3 902-907, Copyright © 1995 by American Physiological Society

ARTICLES

Metabolic responses of rat respiratory muscles to voluntary exercise training

A. E. Halseth, D. L. Fogt, R. F. Fregosi and E. J. Henriksen
Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721, USA.

Voluntary wheel running for 4 or 8 wk was used to assess whether a volitional training stimulus would induce adaptations in the oxidative capacity [citrate synthase activity (CS)], glucose phosphorylation capacity [hexokinase activity (HK)], and glucose transporter protein level (GLUT-4) of rat respiratory muscles. Running distances averaged approximately 10-13 km/day over the final 5 wk of training. Peak oxygen consumption by the trained animals was 17% greater (P < 0.05) than by age-matched sedentary control animals after 8 wk. CS, HK, and GLUT-4 in soleus and plantaris muscles all increased because of exercise training. CS increased in the rectus abdominis (+17%), external oblique (+28%), and internal oblique (+17%) but not in the costal or crural diaphragm after 4 wk of training. However, after 8 wk, CS in the costal diaphragm was 39% greater than control but was unchanged in the crural diaphragm. Whereas HK was significantly greater than control in the costal diaphragm (+18%) and rectus abdominis (+54%) after 4 wk, 8 wk of running were required for increases in HK in the external oblique (+17%) and internal oblique (+14%). HK in the crural diaphragm was not significantly altered by the exercise training. GLUT-4 did not change significantly in any of the respiratory muscles studied. These results indicate that significant adaptations in the glucose phosphorylation capacity and oxidative capacity of both inspiratory and expiratory muscles can take place in response to voluntary exercise. However, this same stimulus is not sufficient to cause an adaptive response in GLUT-4 protein level in these respiratory muscles.

This article has been cited by other articles:

				I. J. Smith and S. L. Dodd Muscle: Calpain activation causes a proteasome-dependent increase in protein degradation and inhibits the Akt signalling pathway in rat diaphragm muscle Exp Physiol, May 1, 2007; 92(3): 561 - 573. [Abstract] [Full Text] [PDF]

				B Polla, G D'Antona, R Bottinelli, and C Reggiani Respiratory muscle fibres: specialisation and plasticity Thorax, September 1, 2004; 59(9): 808 - 817. [Abstract] [Full Text] [PDF]

				C.-H. Kim, J. H. Youn, J.-Y. Park, S. K. Hong, K. S. Park, S. W. Park, K. I. Suh, and K.-U. Lee Effects of high-fat diet and exercise training on intracellular glucose metabolism in rats Am J Physiol Endocrinol Metab, June 1, 2000; 278(6): E977 - E984. [Abstract] [Full Text] [PDF]

				P. E. Willis, S. G. Chadan, V. Baracos, and W. S. Parkhouse Restoration of insulin-like growth factor I action in skeletal muscle of old mice Am J Physiol Endocrinol Metab, September 1, 1998; 275(3): E525 - E530. [Abstract] [Full Text] [PDF]