Vaso-Depressor Phenomenon Caused by Some Cholecystokinin Preparations.

Abstract

Throughout our work on the purification of cholecystokinin, we have not infrequently observed that certain preparations on their first injection into some dogs under barbital anesthesia cause marked contraction of the gall-bladder, followed by a slow fall in blood pressure (30-60 mm. Hg.) with a gradual return to normal, and a stimulation of respiration (which does not always occur) that appears soon after the blood pressure begins to fall. (The contraction of the gall-bladder persists from 10 to 20 minutes after the blood pressure and respiration have returned to normal. A second injection of the same material some 10 or 20 minutes later causes the gall-bladder to contract, but has no effect on the blood pressure and respiration. Apparently some rapid compensatory change or readjustment has occurred in the animal.

Two possible explanations of this phenomenon have occurred to us: one, that a rapid and violent contraction of the gall-bladder stimulates vagus endings and leads to the change in blood pressure and respiration; the other, that there is some toxic element in the preparation to which the dog rapidly immunizes or adjusts itself. This latter possibility seems reasonable since our records show that we have only observed this phenomenon when the cholecystokinin was prepared from hog's intestines, and it has not occurred when dog's intestines were used. The dog's intestines used are very fresh, but we have to wait some 15 or 20 minutes after the death of the hog before we can get the intestine. Our hog material has never been as pure as our dog material.