The effect of acetylcholine on bile flow.

The effect of acetylcholine on bile flow was studied in isolated perfused rat liver. Acetylcholine added into the perfusion medium altered bile flow in a way analogous to mechanical clamping and opening of the common bile duct. This effect was potentiated by physostigmine and antagonized by atropine. The results suggest that acetylcholine can pass from portal sinusoidal blood into the biliary tract, possibly through the terminal bars of bile canaliculi, and cause an obstruction in the biliary tree. Suggested mechanism could explain the observed decreased and increased bile flow caused by cholinergic drugs or vagal stimulation in the earlier experiments.