Inhibition by colchicine of biliary secretion of diethylmaleate in the rat: evidence for microtubule-dependent vesicular transport.

It has been proposed that a microtubule-dependent transport of vesicles derived from the Golgi apparatus may play a role in biliary secretion of bile salts and other cholephilic anions. To test this hypothesis, we examined the influence of colchicine and vinblastine, two microtubule inhibitors, on diethylmaleate-induced bile flow and on the biliary secretion of diethylmaleate, an organic anion whose glutathione conjugates may be secreted into bile through the Golgi apparatus and Golgi-derived vesicles. Rats were pretreated with colchicine or vinblastine, and diethylmaleate was injected intraperitoneally at doses of 28 to 400 mumol/100 gm body wt. Basal bile flow was unaffected by colchicine or vinblastine. In contrast, diethylmaleate-induced bile flow and the secretion into bile of diethylmaleate conjugates (estimated by the cation-anion gap in bile) were significantly lower in colchicine-treated and vinblastine-treated animals than in controls. Diethylmaleate-induced bile flow was reduced in proportion to diethylmaleate conjugate secretion. A linear relationship was seen between bile flow and biliary output of diethylmaleate conjugates: this relationship was similar in colchicine-treated or vinblastine-treated animals and in controls. At electron microscopy, diethylmaleate had induced distension of the Golgi saccules of the hepatocytes. In conclusion, colchicine and vinblastine inhibited the secretion into bile of diethylmaleate conjugates and diethylmaleate-induced bile flow. These results support the view that microtubule-dependent transport of Golgi-derived vesicles is involved in the biliary secretion of diethylmaleate and, perhaps, other cholephilic organic anions.