Yiamouyiannis C A, Martin B J, Watkins J B
Medical Sciences Program, Indiana University School of Medicine, Bloomington.
J Pharmacol Exp Ther. 1993 Apr;265(1):321-7.
Recent studies have indicated that exercise causes alterations in the biotransformation of some xenobiotics and the clearances of antipyrine and [14C]aminopyrine. The present study has investigated whether chronic voluntary physical activity alters hepatobiliary excretory function by comparing the clearance and biliary excretion of model substrates for each of four carrier-mediated transport systems (anion, uncharged, bile acid and cation; n = 8 for each chemical in each group) in active and inactive female rats. The active rats had access to running wheels and voluntarily ran 11.2 +/- 0.68 km/day. The active rats were fed ad libitum, and ate 37% more food than weight-matched, restricted-fed sedentary control rats. Basal bile flow was 34% higher in active rats than in inactive rats, and excretion of bile acids, cholesterol and phospholipid were also increased. The biliary excretion and biliary clearance of the anion, indocyanine green, were elevated in active rats, although total clearance and serum concentrations were not different due to decreased non-biliary clearance. Serum elimination and total clearance of the uncharged substrate, ouabain, were elevated in the active rats, due entirely to increased nonbiliary clearance. Total clearance of the bile acid, taurocholate, was higher in active rats due to an increased biliary clearance. In contrast, there were no differences in either the biliary excretion or clearances of the cation, procainamide ethobromide, between the two groups of rats. Finally, no differences in volume of distribution or elimination half-life were noted between inactive and active rats for any of the substrates.(ABSTRACT TRUNCATED AT 250 WORDS)
