Influence of Various Chemical Agents on the Absorption of Histamine From the Intestine.

Abstract

Histamine has been shown to be present in the intestinal contents of man and of some other mammals. In view of its powerful pharmacological effects, the question of its absorption has received considerable attention. It can be absorbed from the intestine of the cat in sufficient amounts to produce a marked lowering of blood pressure. 1 Under similar conditions, however, the blood pressure of the dog is not affected. 2 In man as much as 225 mg. has been taken by mouth with no noticeable effect except a moderate stimulation of gastric secretion. 3 It has not thus far been shown that any pathological condition materially affects the behavior of the intestine toward histamine. Previous workers have studied the effects of temporary interruption of the blood supply, 1 of intestinal obstruction, and of distention, 4 with negative or inconclusive results.

Spadolini 5 treated the mucosa of the dog's intestine with diluted chloroform, and observed symptoms which he attributed to an increased absorption of the products of bacterial decomposition of proteins. There was, however, no direct evidence of such a change in permeability toward any specific substance. We have studied the effect of chloroform, and of a number of other agents, on the absorption of histamine.

In small dogs, under barbital anesthesia, a rubber catheter was passed down into the duodenum from the stomach. A ligature around the pylorus fixed the catheter in place and prevented regurgitation. Blood pressure, respiration, and pancreatic secretion were recorded.

In control experiments, 5 mg. of histamine dichloride per kilo body weight was introduced into the duodenum. No change in blood pressure was ever produced. In another series of animals, we first introduced 5 to 10 cc. of chloroform, diluted with 1 to 2 volumes of paraffin oil.