MICHAUD, T. J., K. A. BACHMANN, F. F. ANDRES, M. G. FLYNN, G. P. SHERMAN, and J. RODRIGUEZ-ZAYAS. Exercise training does not alter cytochrome P-450 content and microsomal metabolism. Med. Sci. Sports Exerc., Vol. 26, No. 8, pp. 978-982, 1994. The purpose of this investigation was to determine whether increased endurance exercise capacity alters total hepatic cytochrome P-450 content and cytochrome P-450 (CYP1A and CYP2B) mediated hepatic microsomal mixed-function oxidase drug metabolism. Twenty adult male Sprague-Dawley rats were randomly assigned to either a control (C) or an endurance trained group (ET). ET rats were progressively trained 5 d [middle dot] wk-1 for 11 wk. Both C and ET rats were administered in random order single posttraining doses of probe drugs theo-phylline (probe for CYP1A) and anlipyrine (probe for CYP2B). Soleus muscle citrate synthase activity of ET rats was significantly greater (P < 0.01) than for C rats (mean +/- SD; C,26.4 +/- 1.3 +/- mol [middle dot] g-1 [middle dot] min-1; ET, 46.1 +/- 2.7). In contrast, total liver cytochrome P-450 content was not significantly different (P < 0.01) among C and ET rats (mean +/- SD; C, 0.554 +/- 0.055 nmol [middle dot] mg-1 liver protein; ET, 0.604 +/- 0.080). Likewise, the posttraining C and ET single-sample plasma clearances of theophylline (mean +/- SD; C,1.89 +/- 0.360 l [middle dot] h-1kg-1 total liver weight; ET, 2.08 +/- 0.49) and antipyrine (mean +/- SD; C, 6.44 +/- 1.56 l [middle dot] h-1kg-1 total liver weight; ET, 6.51 +/- 1.02) were not significantly different (P > 0.01). Therefore, it was concluded that strenuous endurance training of 11 wk duration did not alter total hepatic cytochrome P-450 content or CYP1A or CYP2B activity.
(C)1994The American College of Sports Medicine