The possible role of histamine in the coritsone induced gastric acid hypersecretion of the guinea-pig.

1. The effects of cortisone treatment combined with agents influencing histamine metabolism were studied on the free and total acid output in pylorus ligated guinea-pigs.2. It was found that reduction in the synthesis of histamine produced by the administration of alpha-methylDOPA significantly inhibited the acid response to cortisone.3. Enhancement of the oxidative deamination of histamine brought about by the administration of diamine oxidase or heparin inhibited cortisone induced acid hypersecretion significantly.4. Inhibition of the oxidative deamination of histamine by aminoguanidine and iproniazid resulted in a significant increase of the cortisone induced acid hypersecretory response.5. Inhibition of the methylation of histamine by chlorpromazine or 1,4-methylhistamine inhibited the cortisone induced hypersecretory response significantly.6. Studies with labelled histamine indicated that cortisone increases the sequestration of histamine to the stomach.