Blood Pressure in Unanesthetized Animals Affected by “Vasopressin,” Oxytocin,” Pituitary Extract and Other Drugs

Abstract

Recently Kamm, Aldrich, Grote, Rowe and Bugbee 1 separated from pituitary extracts what they believe to be nearly pure vasopressor and oxytocic hormones. These hormones recently were placed on the drug market under the names “Vasopressin” and “Oxytocin”. Gargle, Gilligan and Blumgart, 2 Ward, Lyon and Bemis 3 have studied the effect of vasopressin upon blood pressure with uncertain results. This work was undertaken to determine if vasopressin affects the blood pressure in unanesthetized experimental animals and if so in what way does it change it.

Dogs and cats were used. In cats the operative work was done under ether anesthesia and the animals were permitted to recover. In the unanesthetized dogs local 1% procain anesthesia was used. Experiments were also performed upon dogs under chloretone anesthesia as directed by the original investigators. 1

In animals under chloretone anesthesia vasopressin caused a rise in blood pressure although histamine produced its typical fall. In unanesthetized dogs and cats the initial injection of vasopressin caused, after a temporary slight rise, a precipitate fall in blood pressure, in some cases as much as 150 mm. of mercury. This was accompanied by a slow pulse, grouped cardiac contractions, pale, dry mucous membranes, with decreased respiration. This was followed by a prolonged rise in blood pressure, in most instances above the normal. A11 subsequent injections were followed either by a rise in blood pressure or no change.

In an unanesthetized animal pituitary extract caused a rise in blood pressure and oxytocin either no effect or a slight rise or fall in blood pressure.

Acetyl choline caused a decreased blood pressure and an increase after the injection of atropine in unanesthetized dogs. Vasopressin caused its typical fall in blood pressure after atropine administration.