IS MAST-CELL HISTAMINE INVOLVED IN THE REGULATION OF ACID-SECRETION IN THE GUINEA-PIG STOMACH

In order to find out whether mast cell histamine is involved in acid s ecretion in the guinea pig stomach, we tried to answer the following q uestions. Can the calcium ionophore (CaI), A23 187, release enough mas t cell histamine to evoke acid secretion? Does electrical stimulation of the vagus nerve (VS) provoke any changes in mast cells in the stoma ch? In the experiments, an isolated part of guinea pig stomach was use d. Preparations from CaI and VS treated groups were examined histologi cally at the end of experiments. CaI evoked a clear secretory response that was blocked by famotidine. The H2 antagonist also blocked the se cretory effect of VS. This result shows that these secretory effects w ere at least partly mediated by the released histamine. Connective tis sue mast cells in CaI treated preparations and in preparations with VS showed significant degranulation. These results support the hypothesi s that mast cell histamine could be involved in gastric acid secretion in guinea pig stomach.