Stimulation of gastric acid secretion increases mucosal blood flow in immediate vicinity of parietal cells in baboons

Abstract

In acute experiments carried out in 27 baboons under general anesthesia, the regional gastric mucosal and muscle layer blood flow and gastric acid secretion were measured during 4 hr. Baboons were allocated to each of the following six groups: control, gastric acid stimulation with histamine 40 micrograms/kg/hr intravenous, inhibition of basal or stimulated acid secretion with either ranitidine 50 mg intravenous or omeprazole 1 microgram/kg/hr. There were no significant cardiovascular alterations during the experiments. Histamine stimulation produced a concomitant rise in acid secretion and increase in blood flow only to the mucosal layer of the parietal-cell-bearing area of the stomach. Neither the underlying muscle layer nor the non-parietal-cell-bearing fundic or antral mucosa took part in this response, suggesting that a mechanism controlling blood flow is present in close proximity to the parietal cells. It was also established that the increase in blood flow occurs in response to parietal cell activity and not as a result of the action of histamine on the vascular system. Suppression of both basal and stimulated acid secretion did not cause a fall of mucosal blood flow below basal levels in any part of the stomach, indicating that drugs that inhibit parietal cell activity can be used in conditions where gastric mucosal ischemia should be avoided.