Effects of the sympathoadrenal system on vagally induced gastric acid secretion and mucosal blood flow in rats.

Effects of the sympathoadrenal system on vagally induced increases in gastric acid secretion and mucosal blood flow (MBF) were studied in anesthetized, gastric fistula rats. Greater splanchnic nerve stimulation reduced significantly both the gastric acid secretion and MBF. Stimulation of the splanchnic postganglionic nerve reduced to a greater extent the acid secretion than the MBF, while stimulation of the adrenal branch reduced both the acid secretion and MBF. Infusion of epinephrine also reduced both the acid secretion and MBF, but the reduction of MBF was the more prominent. Phentolamine, but not propranolol and alprenolol, reduced the inhibitory effects on both gastric functions of the splanchnic postganglionic nerve stimulation and adrenal branch stimulation or epinephrine infusion. These results suggest that catecholamines released from the splanchnic postganglionic nerve terminals inhibit gastric acid secretion through alpha adrenergic receptors in the stomach, independent of MBF, and that circulating catecholamines released from the adrenal medulla inhibit both the acid secretion and MBF through alpha adrenergic receptors in the stomach. The inhibition by greater splanchnic nerve stimulation is probably the sum of the effects induced by catecholamines released from the splanchnic postganglionic nerve terminals and from the adrenal medulla.