[The influence of clanobutin on bile secretion in the isolated perfused rat liver (author's transl)].

Isolated perfused rat liver was used to characterize the choleretic action of 4-[4-chloro-N-(4-methoxyphenyl)-benzamido]-butyric acid (clanobutin). The dose-dependent increase of the bile flow was associated with an increase of the Na+ secretion. In in vitro studies the drug inhibited the Na+-K+-ATPase of the sinusoidal membrane more than that of the canalicular membrane in a dose-dependent manner. The following hypothesis was proposed to explain the choleretic action of clanobutin. The intracellular Na+ concentration increased due to the inhibition of the sinusoidal Na+-K+-ATPase. This is then compensated by transporting the extra Na+ into the bile. However, it cannot be ruled out that Na+ is transported as counterion during hepatobiliary transport of clanobutin or else its metabolites. The effect of the drug seems to be non-specific since other enzymes of the plasma membrane were also inhibited.