ACTIVITY OF OXYNTOMODULIN ON GASTRIC-ACID SECRETION INDUCED BY HISTAMINE OR A MEAL IN THE RAT

Conscious rats with chronic gastric fistula were trained far drinking a 14-ml milk meal. The activity of an intestinal hormone, oxyntomoduli n (OXM), was studied in this model and compared to that observed when histamine was the stimulus. Under histamine (0.25 mg.kg(-1).h(-1)) sti mulation, OXM at doses (60-120 pmol.kg(-1).h(-1)) that induced physiol ogical circulating levels inhibited gastric acid secretion up to 50%. Under meal stimulation, OXM reduced up to 29% acid secretion at doses (1-1.5 nmol kg(-1) h(-1)) inducing supraphysiological levels. We concl ude that at physiological concentrations OXM cannot counteract the com plex processes triggered by a meal. OXM would be a component of entero gastrone, a combination of several intestinal hormones acting in syner gy. The OXM action is related to pathways recognizing the C-terminal 1 9-37 moiety of the molecule.