title: Effect of adrenergic antagonists on clonidine-induced inhibition of basal gastric secretion in conscious rats.
abstract: In unanesthetized rats with chronic gastric fistulas the mechanism of the inhibitory action of clonidine (CLO) on basal gastric secretion was investigated. CLO (0.001-1 mg/kg ip) reduced significantly in a dose-dependent fashion, the basal gastric acid output, and after higher doses no secretion occurred. Noradrenaline (0.1-2.5 mg/kg ip) even in much higher doses was less effective in inhibiting basal gastric secretion in rats. A postsynaptic alpha-adrenergic receptor blocker phenoxybenzamine antagonized only moderately the inhibitory effect of CLO. Phentolamine was more potent in this respect and antagonized significantly, by about a half, the antisecretory effect of CLO. Yohimbine, a presynaptic alpha-adrenoceptor blocker, counteracted insignificantly the inhibitory influence of CLO on basal gastric secretion. The alpha-adrenergic inhibitory receptors in the gastric mucosa, stimulated by CLO, are sensitive to both pre- and post-synaptically acting adrenergic blockers.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000187:drug effects; D010643:Phenoxybenzamine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D051381:Rats; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D010643:Phenoxybenzamine; D015016:Yohimbine; D003000:Clonidine; D009638:Norepinephrine; D010646:Phentolamine