[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.
Shi
L
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Resistance Artery Laboratory, Xuzhou Institute of Medical Sciences.
Wang
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YX
Xue
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AQ
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