Gastrin - Histamine as a Normal Sequence in Gastric Acid Stimulation in the Rabbit

In a suspension of isolated gastric glands the effect of secretagogues on the oxyntic cells can only be detected by direct stimulation. An indirect stimulus like gastrin inducing one type of cell to liberate histamine which then acts on the oxyntic cells will not be detectable because of the very high dilution of the liberated substance. Thus the isolated gland preparation presents a means by which two steps in a sequential stimulation can be separated. There is no evidence that gastrin acts directly on the oxyntic cells but it does liberate histamine in a dose-effect relationship, which would in an intact stomach give histamine concentrations sufficient to effectively stimulate the acid secretion. Thus in the rabbit histamine seems to be a normal physiological mediator for gastrin stimulation.