Vagal stimulation of duodenal HCO3 ‐secretion in anaesthetized rats

Publisher Website
Google Scholar
Abstract
The present study was designed to examine the influence of the vagal nerves on mucosa protective duodenal HCO3(-)-secretion in chloralosed rats. The HCO3(-)-secretion was measured by in situ titration in a duodenal segment devoid of Brunner glands. Cervical vagotomy lowered duodenal HCO3(-)-secretion and stimulation of the cut vagal nerves (10 Hz for 15 min) increased this secretion. Both basal and vagally stimulated duodenal HCO3(-)-secretions were more pronounced in rats with ligated adrenal glands. Atropine did not influence basal duodenal HCO3(-)-secretion, whereas indomethacin and hexamethonium lowered basal secretion in vagotomized rats with ligated adrenal glands. Compared with untreated controls, vagally induced secretory responses were unchanged by atropine, 50% smaller in indomethacin treated rats and almost abolished in rats treated with hexamethonium. The study suggests that the vagal nerves exert an excitatory effect on duodenal HCO3(-)-secretion which is mainly mediated via nicotinic, non-muscarinic transmission, in part dependent on prostaglandin synthesis. Furthermore, the results indicate that the adrenal glands exert an inhibitory action on both the basal and vagally induced mucosa protective HCO3(-)-secretion.