title: Study of propranolol and its related adrenoceptor antagonists on changes of gastric electrical parameters induced by ethanol in rats.
abstract: The actions of different adrenoceptor antagonists on gastric potential difference (PD), electrical current (I) and resistance (R) were studied, using the voltage clamp technique. In an isolated gastric mucosal tissue, 5% ethanol was able to reduce the PD and I across the gastric mucosa. Direct incubation with propranolol 10(-4) mol/l either from the mucosal or submucosal sides attenuated such effects. Intraperitoneal administration of propranolol (2.5-10 mg/kg), a nonselective beta-adrenoceptor blocker with significant membrane-stabilizing activity, given 30 min before the preparation of the gastric tissue, not only alleviated the fall in PD and I across the gastric mucosa, but also increased the R of the stomach tissue. Butoxamine, a selective beta2-antagonist, produced the similar but less significant effects in the same experimental setting. Metroprolol, a beta1-adrenoceptor blocker, given by the similar doses did not produce significant effects. Nonselective beta-adrenoceptor blocker, nadolol but not the beta- and alpha-adrenoceptor blocker, labetalol, also significantly preserved the decrease of PD induced by ethanol, but to a lesser extent. These findings suggest that blockade of the beta2-receptors in the gastric mucosa together with membrane-stabilizing activity could improve the integrity of the gastric mucosa, and these effects are probably acting through its direct action on the tissue.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Hong Kong, China.
authors.forename: S K
authors.initials: SK
authors.lastname: Kaan
authors.forename: C H
authors.initials: CH
authors.lastname: Cho
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002078:Butoxamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D004594:Electrophysiology; D000431:Ethanol / Q000494:pharmacology*; D005753:Gastric Mucosa / Q000187:drug effects* / Q000502:physiology; D007741:Labetalol / Q000494:pharmacology; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D009248:Nadolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000319:Adrenergic beta-Antagonists; D002078:Butoxamine; D000431:Ethanol; D009248:Nadolol; D011433:Propranolol; D008790:Metoprolol; D007741:Labetalol