title: Comparison of inhibitory effects of calcium channel blockers and that of a calmodulin antagonist in strips of mesenteric arteries from spontaneously hypertensive and normotensive rats.
abstract: Effects of calcium channel blockers and of calmodulin antagonist on the contractile responses to norepinephrine (NE) were compared between strips of mesenteric arteries from 6- and 14-week-old spontaneously hypertensive rats (SHR) and age-matched, normotensive Wistar-Kyoto rats (WKY). The ratio of the maximum contraction developed by NE to that by 60 mM KCl was significantly increased in strips from 14-week-old SHR. Niludipine, verapamil and diltiazem antagonized the maximum NE contraction to a greater extent in strips from 14-week-old SHR than in those from the WKY. However, the antagonism by niludipine of the KCl- or caffeine-induced contraction was not significantly different between the strips from 14-week-old SHR and those from WKY. In strips from 6-week-old rats, there was no difference in the antagonism by niludipine of the maximum NE contraction. On the other hand, the effect of W-7 on the maximum NE contraction was not significantly different between the strips from 14-week-old SHR and those from WKY. Schild plot analyses demonstrated that alpha 1-adrenoceptors were the same for the strips from SHR and WKY. These results suggest that the enhanced maximum NE contraction in the mesenteric artery from 14-week-old SHR reflects the increased transmembrane influx of calcium, and the activity of calmodulin seems to be the same for the two strains.
authors.affiliation: Department of Pharmacology, Nagoya City University Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Asano
authors.forename: K
authors.initials: K
authors.lastname: Masuzawa
authors.forename: M
authors.initials: M
authors.lastname: Kojima
authors.forename: K
authors.initials: K
authors.lastname: Aoki
authors.forename: T
authors.initials: T
authors.lastname: Matsuda
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D005260:Female; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013449:Sulfonamides / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers; D002147:Calmodulin; D013449:Sulfonamides; C017967:W 7; D011188:Potassium; D009638:Norepinephrine