Modulation of stimulated acid secretion by dibutyryl cyclic AMP in the dog stomach

An in vivo canine gastric chamber preparation was used to determine effects of exogenous cyclic AMP and dibutyryl cyclic AMP on histamine-driven acid secretion and the role of blood flow in these responses. Histamine was infused intravenously at a submaximal rate 1.2 mu/kg-min) followed by the intraarterial infusion of either cyclic AMP (0.15 mg/kg-min) or dibutyryl cyclic AMP (0.15 mg/kg-min. Acid secretion and mucosal blood flow (aminopyrine clearance) were measured at 15-minute intervals, and electrical potential difference was measured continuously. Histamine alone decreased the potential difference from 82 mV to 48 mV within 60 minutes, increased aminopyrine clearance from 1.0 ml/min to 2.4 ml/min and increased acid output to 220 muEq/15 min. All values returned towards control following termination of histamine infusion. Dibutyryl cyclic AMP significantly increased histamine stimulated acid secretion to 350 muEq/15 min, but did not alter mucosal blood flow or electrical potential. Cyclic AMP did not change secretory, circulatory or electrical response to histamine. Therefore, dibutyryl cyclic AMP appears to increase histamine-stimulated acid secretion, and the effect is not mediated by increased mucosal blood flow.