Effect of diethyl maleate pretreatment on biliary excretion and choleretic action of sulfobromophthalein in rats.

The effect of intraperitoneal administration of diethyl maleate on biliary excretion and choleretic action of sulfobromophthalein (BSP) was investigated in rats. Diethyl maleate was injected 60 min prior to the administration of the dye to avoid interferences with the organic anion transport system. The glutathione content of the liver was decreased by 75% following diethyl maleate treatment. Diethyl maleate had no influence on the biliary excretion of BSP after injection of its conjugate with glutathione, though there was a significant reduction after free BSP administration, with a lowered percentage of the conjugate in bile. The choleretic effect of the dye was not changed after conjugated BSP, but a marked cholestasis appeared following free BSP injection. These results confirm that diethyl maleate decreases the hepatic transport of BSP by reducing the conjugation of the dye and that free BSP induces an inhibitory effect on bile flow.