Chronic physical activity alters hepatobiliary excretory function in rats

Area of Science:

• Physiology
• Pharmacology
• Exercise Science

Background:

• Exercise is known to affect xenobiotic metabolism and drug clearance.
• The impact of chronic physical activity on hepatobiliary excretory function requires further investigation.

Purpose of the Study:

• To determine if chronic voluntary physical activity alters hepatobiliary excretory function.
• To compare the clearance and biliary excretion of model substrates for four carrier-mediated transport systems in active versus inactive rats.

Main Methods:

• Active female rats voluntarily ran on running wheels, while sedentary controls were weight-matched and food-restricted.
• Biliary excretion and clearance of model substrates for anion, uncharged, bile acid, and cation transport systems were measured.
• Basal bile flow, bile acid, cholesterol, and phospholipid excretion were also assessed.

Main Results:

• Active rats exhibited a 34% increase in basal bile flow and elevated excretion of bile acids, cholesterol, and phospholipids.
• Biliary excretion and clearance of the anion indocyanine green were increased in active rats.
• Serum elimination and total clearance of the uncharged substrate ouabain were elevated due to increased nonbiliary clearance.
• Total clearance of the bile acid taurocholate was higher in active rats due to increased biliary clearance.
• No differences were observed in the transport of the cation procainamide ethobromide.

Conclusions:

• Chronic voluntary exercise enhances hepatobiliary excretory function in female rats.
• Specific transport systems, including those for anions and bile acids, are positively affected by physical activity.
• Cation transport function is not altered by chronic exercise in this model.