Phenoxybenzamine-sensitive sites are not responsible for the mechanoreception of membrane stretch leading to myogenic contraction of dog cerebral artery.
Effects of phenoxybenzamine on the myogenic contraction in response to quick stretch were examined in the isolated dog cerebral artery. Quick stretch at a rate of 10 cm/sec by 30% of the initial muscle length (= 100%) produced a myogenic contraction in dog basilar artery. Pretreatment of the cerebral artery strips with phenoxybenzamine (10(-4) M) for 30 min inhibited the stretch-induced contraction by 50-60%. By comparison, the treatment with phenoxybenzamine abolished the cerebral artery contractions induced by 5-hydroxytryptamine and histamine. Norepinephrine-induced contraction was also suppressed to about 10% by the treatment with phenoxybenzamine. High KCl (80 mM)-induced depolarizing contraction was nearly completely inhibited by the phenoxybenzamine treatment. These findings suggest that the site(s) of mechanoreception of membrane stretch (quick stretch) leading to myogenic contraction of dog cerebral artery is not susceptible to alkylation by phenoxybenzamine. It seems likely that mechanosensor site(s) responsible for inducing myogenic contraction by quick stretch is distinct from the sites for the reception of chemical stimulations.
Tanaka
Y
Y
Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Nakayama
K
K
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D002536:Cerebral Arteries; D004285:Dogs; D004347:Drug Interactions; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010643:Phenoxybenzamine / Q000494:pharmacology*; D011311:Pressoreceptors / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D016166:Free Radical Scavengers; D010643:Phenoxybenzamine; D012701:Serotonin; D006632:Histamine