Direct regulation of bile secretion by prostaglandins in perfused rat liver

Prostaglandins have been postulated to act as mediators of intercellular communication between liver cell populations in the regulation of liver carbohydrate metabolism. Their role in the regulation of bile secretion is rather unclear. The action of prostaglandins on bile flow and bile acid secretion was studied in the in situ perfused rat liver. Infusion of prostaglandin F2 alpha resulted in reduction of bile flow and bile acid secretion. In addition, portal flow was diminished and glucose output was increased. The parameters were altered in a dose-dependent manner. The effects of prostaglandins D2 and E2 were similar but less potent than those of prostaglandin F2 alpha. To separate the effects on portal flow and bile flow, we used nitroprusside and nifedipine to suppress the hemodynamic changes induced by prostaglandins. In the presence of these substances, the alterations of bile flow and bile acid secretion were even more pronounced. Infusion of inhibitors of prostaglandin synthesis increased bile flow. In conclusion, prostaglandins F2 alpha, D2 and E2 reduce bile flow and bile acid secretion. These effects are independent of hemodynamic changes. Suppression of synthesis of endogenous prostaglandins by inhibitors of prostaglandin synthesis reversed these effects. Prostaglandins are involved in the regulation of bile flow and bile acid secretion.