Ursodeoxycholate-induced choleresis in taurine-deprived and taurine-supplemented rats

The effect of i.v. infused ursodeoxycholate (1.2 micromol/(min . 100 g body weight)) was compared in control rats and in taurine supplemented (i.p. administration of a taurine solution) and taurine deprived (oral administration of beta-alanine) rats. In the control rats, the bile water output during the first hr was significantly lower than that of the second hr, while the bile salt output was significantly lower in the second hr. In beta-alanine pretreated rats, the increase in the bile flow in the first hr was more rapid compared to control rats, and the bile flow rate reached a peak earlier. The first hr and total 2 hr bile water outputs were significantly higher in the beta-alanine pretreated rats compared to the corresponding bile flow values of the control rats, while the bile salt outputs were significantly lower than respective control values. In taurine supplemented rats, the increase in bile flow in the second hr was less than in control rats, while the bile salt excretion rate was the highest among the three rat groups. Thus, among these three groups, the bile flow and bile salt excretion rate during the first hr and 2 hr total infusion periods were negatively correlated. On the other hand, a significant positive correlation was observed between the bile flow rate for 1 or 2 hr and bile salt concentration in the liver examined after a 1 or 2 hr bile salt infusion. These results seem most easily explained by our previous thesis that at least part of the bile is produced not by the excretion of bile salt into the bile canaliculus but by its presence inside the hepatocyte (secretory mechanism).