The effect of acetylcholine on biliary excretion of ouabain in the physostigmine pretreated isolated perfused rat liver.

The effect of acetylcholine (ACh) on bile flow and biliary excretion of 3H-ouabain was studied in the physostigmine pretreated isolated perfused rat liver. ACh added into the perfusion medium to give a concentration of 1 X 10(-4)M after the addition of physostigmine (2 X 1 X 10(-5)M) transiently decreased bile flow and biliary concentration of tritium, originated from 3H-ouabain. A deficit of 34 mul of bile during the decreased bile flow could be calculated, compared to the control group. This deficit in bile flow possibly reflects an inhibitory secretory effect of ACh on canalicular bile secretion, or enhanced reabsorption of water in the biliary tree. The decline in the concentration of 3H-oubain in the bile after the addition of ACh indicates that ACh inhibits biliary transport of ouabain by an unknown mechanism, in addition to its effect on bile flow. Physostigmine alone possibly was without an effect on biliary elimination of ouabain. The results show that ACh retards the biliary elimination of ouabain through its influence on bile flow and biliary concentraton of ouabain.