Effect of Histamine on the Secretion of Gastric Pepsin.

Abstract

Histamine is known generally as a gastric secretogogue, and the results of many investigations have shown that the secretion of the normal stomach, in response to this stimulus, is rich in free acid; the response of the peptic glands, however, has received but slight attention. In a series of experiments upon human subjects, Polland and Bloomfield 1 have observed that with an increased volume of gastric secretion in response to a histamine stimulation there is a progressive decrease in pepsin concentration, although the total amount of pepsin secreted is actually greater.

A new micro technique for estimating peptic activity was recently developed in this laboratory. 2 Utilizing this method in a series of experiments upon dogs possessing either Pavlov or Heidenhain pouches the authors find that:

(a) With increased volume of secretion produced by histamine stimulation there is a progressive decrease in the concentration of pepsin in the gastric juice.

(b) The pepsin concentration of the fasting juice is invariably greater than that of any subsequent sample.

(c) In the first sample of juice obtained following histamine stimulation the concentration of pepsin is diminished, but due to the increased volume of flow, the total amount of pepsin apparently secreted per unit of time is greatly increased.

(d) In subsequent samples the concentration of pepsin and the total amount of enzyme secreted per unit of time is rapidly diminished.

(e) Examination of samples collected subsequent to 45 minutes after the injection of histamine shows with few exceptions, that the total pepsin secreted per unit of time is less than is the case before the administration of histamine. The concentration of pepsin in these samples may be as low as 1/40 the concentration found in the fasting juice.

(f) The content of pepsin in the sample is roughly parallel to the content of neutral chloride.