title: Effects of adrenoceptor antagonists on vagally induced gastric and duodenal HCO3- secretions in the cat.
abstract: Experiments were performed on chloralosed cats with ligated adrenal glands. The cervical vagi were cut and arranged for electric stimulation. The gastric lumen was continuously perfused, and the secretions of H+ and HCO3- were calculated from pH/pCO2 measurements in the perfusate. Gastric motility was recorded as changes in hydrostatic pressure within the perfusion system. Mucosal HCO3- secretion into a duodenal segment, distal to the papilla of Vater and Brunners gland area, was titrated in situ by a pH-stat equipment. Animals pretreated with various adrenoceptor blockers or splanchnicotomy were compared with control animals with intact sympatho-adrenergic system. Basal gastric motor activity, H+ and HCO3- secretions, as well as duodenal HCO3- secretion were not influenced by prazosin, propranolol or splanchnicotomy. Yohimbine increased significantly basal gastric HCO3- secretion, but did not influence basal gastric motor activity, H+ secretion or duodenal HCO3- secretion. Vagal stimulation in yohimbine-treated or splanchnicotomized animals induced significantly larger gastric contractions, HCO3- secretory and duodenal HCO3- secretory responses than in the controls, whereas these responses to vagal stimulation were small in prazosin- or propranolol-treated animals. Vagally induced gastric H+ secretory responses were significantly larger in propranolol-treated animals than in controls, whereas prazosin-treated, yohimbine-treated or splanchnicotomized animals in this regard did not differ from the controls. The results suggest the existence of a sympathetic, probably alpha-2-adrenergic, inhibition of vagally induced gastric contractions as well as of the gastric and duodenal HCO3- secretions.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002415:Cats; D004386:Duodenum / Q000187:drug effects*; D004558:Electric Stimulation; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D007419:Intestinal Secretions / Q000378:metabolism*; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013153:Splanchnic Nerves / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D001639:Bicarbonates; D015016:Yohimbine; D011433:Propranolol; D011224:Prazosin