Puerarin induces an endothelium-independent relaxation in rat aortic rings. - GreenMedInfo Summary

To investigate the vasorelaxant effect of puerarin, tension was recorded from rat thoracic aortic rings. Puerarin completely relaxed the contractions induced by phenylephrine (PE) in a concentration-dependent manner in endothelium-intact and endothelium-denuded rat aorta, while had no effect on those preconstricted by a high concentration of potassium chloride (60 mM). Also, puerarin had no effects on the transient contraction elicited by PE or caffeine in Ca2+- free medium. The relaxant effect of puerarin was significantly inhibited by pretreatment of endothelium-denuded aorta with potassium channel antagonists tetraethylammonium and 4-aminopyridine, but not glibenclamide. These results indicate that puerarin induces an endothelium-independent relaxation in rat aortic rings. The mechanisms may involve the reduction in Ca2+ influx through the non-voltage-sensitive calcium channels and the activation of the potassium channels (voltage-activated K+ channels and large conductance Ca2+ -activated K+ channels, but not ATP-sensitive K+ channels).