Abstract
Anemoside A3 , a lupane-type triterpenoid saponin, exists in the roots of Pulsatilla chinensis , but its pharmacological properties are largely unknown. The present study aimed to investigate the mechanisms underlying anemoside A3 -induced relaxation in rat renal arteries. Changes of isometric force were determined on arteries with a myograph. Anemoside A3 caused concentration-dependent relaxation in precontracted aortas, mesenteric, left coronary, and renal arteries. Removal of endothelium or treatment with charybdotoxin plus apamin slightly but significantly attenuated the relaxation in renal arteries. TEA+ inhibited the relaxation caused by anemoside A3 in renal arteries with and without endothelium while glibenclamide, BaCl2 , or capsaicin had no effect on it. Anemoside A3 produced less relaxation in rings contracted by 60 mM KCl compared with rings contracted by receptor-dependent constrictors. It further inhibited contractions induced by Ca2+ influx through nifedipine-sensitive voltage-gated Ca2+ channels, nifedipine-insensitive receptor-operated Ca2+ channels, and by intracellular Ca2+ release. Pretreatment with nifedipine attenuated anemoside A3 -induced relaxation. Taken together, the present results indicate that anemoside A3 produces relaxation in rat renal arteries through multiple mechanisms. The release of CTX/apamin-sensitive endothelium-derived hyperpolarizing factor, stimulation of TEA+ -sensitive K+ channel, and inhibition of Ca2+ influx jointly contribute to the relaxation.
Key words
Pulsatilla chinensis
- Ranunculaceae - anemoside A3
- vasorelaxation - Ca2+ channel - endothelium - rat renal arteries
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1 DMZ and SML contributed equally.
Wen-Cai Ye
Institute of Traditional Chinese Medicine and Natural Products College of Pharmacy, Jinan University
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Yu Huang
Institute of Vascular Medicine Li Ka Shing Institute of Health Sciences and School of Biomedical Sciences Chinese University of Hong Kong
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