Session 4: Histamine-Producing Cells in the Stomach and Their Role in the Regulation of Acid Secretion

Abstract

Histamine H2-receptor antagonists inhibit basal and all kinds of stimulated acid secretion with about the same effectiveness, and hence, local release of histamine is thought to be necessary for the stimulation of parietal cells. A local histamine pool is physiologically relevant only if it is within the diffusion distance of the parietal cells, if it is effectively mobilized by gastrin, and if it is endowed with the machinery for a rapid replenishment of the histamine that has been released. Histamine in the stomach occurs in endocrine cells (so-called enterochromaffin-like (ECL) cells), mast cells, and neurons. The ECL cells are peptide hormone-producing cells. In mammals they are located basally in the oxyntic gland area, in the chief-cell-rich region. Parietal cells predominate in t he mid-region. ECL cells respond readily to gastrin with histamine release and histamine resynthesis. Thus, the ECL cells fulfil important prerequisites of a physiologically relevant histamine pool. however, it is not apparent how the preferential localization of ECL cells at the base of the glands may be conducive to a direct effect of released histamine ont he parietal cells, unless histamine reaches the parietal cells via capillary transport from the glandular base. Mast cells are numerous int he stomach of, for example, man, pigs, dogs, and cats. They occur scattered throughout the stomach wall without any obvious relation to the parietal cells.(ABSTRACT TRUNCATED AT 250 WORDS)