Concerning the Mechanism of Contraction of the Gall-bladder in the Guinea Pig

Abstract

After studying the evacuation of bile in the opossum and the cat by cholecystographic methods, 1 and having found that in the opossum contractions of the gall-bladder sufficiently great to be recorded by moving pictures may be induced by faradie stimulation of its wall, 2 it has seemed desirable to investigate anew the extent to which the biliary vesicle is under control of the nervous system. Bearing in mind the emphasis recently placed by Boyden 3 upon species differences in the reactions of mammalian gall-bladders, we have chosen to begin with the guinea pig—that species in which the gall-bladder appears to be more sensitive to a variety of stimuli than in any other vertebrate yet described. 4

All experiments were conducted with the animal under nembutal anesthesia and with the liver gently everted over the costal margin. This routine exposure gave access to the gall-bladder, to the cystic and hepatic ducts and to the structures in the lesser omentum. A heart lever attached to the fundus of the gall-bladder recorded contractions of the vesicle on a smoked drum. To evaluate changes due to respiration and other extraneous movements, a second lever was attached to a bile duct near the hilus of the liver. The possibility of the spreading of the current to the wall of the gall-bladder was ruled out by the fact that faradie stimulation of the stomach, bowel, hepatic ducts and adjacent portions of the liver failed to cause contraction of the biliary vesicle.

With the apparatus thus arranged, marked contractions of the gall-bladder were recorded when the following were stimulated with a weak faradie current: (1) the viscus itself, (2) the duodenal portion (ampulla) of the common bile duct, (3) either vagus nerve in its cervical portion and (4) certain poorly defined cords of the lesser omentum posterior to the common bile duct.