[Relaxing effects of l-stepholidine on rat resistance arteries].
Bolus injection(i.v.) of l-stepholidine(l-SPD, 3 mg.kg-1) caused hypotension in anaesthetized rats. The blood pressure reduction was sustained for 46.3 +/- 14.1 min. In in vitro experiments, l-SPD induced a concentration dependent relaxation of rat mesenteric, cerebral, renal and coronary resistance arteries preconstricted with 125 mmol.L-1 KCl. l-SPD was least potent with cerebral resistance arteries with the -Log EC50 value being 4.25 +/- 0.22. The relaxation of l-SPD on mesenteric resistance arteries was the most potent with the -Log EC50 value being 4.76 +/- 0.15. The larger influence of l-SPD (100 mumol.L-1) on the contraction induced by KCl in mesenteric than in cerebral arteries was in line with the above results. It is indicated that l-SPD has a direct relaxation on visceral resistance arteries with some degree of selectivity and the relaxation would decrease total peripheral resistance and thus constitute an important cause of its hypotensive action.
Resistance Artery Laboratory, Xuzhou Institute of Medical Sciences.
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Wang
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Xue
D000818:Animals; D001599:Berberine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D014655:Vascular Resistance / Q000187:drug effects*
D002121:Calcium Channel Blockers; D001599:Berberine; C010513:stepholidine