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Yonsei Medical Journal ; : 14-23, 1992.
Artículo en Inglés | WPRIM | ID: wpr-153235

RESUMEN

Isolated rabbit aortic ring with intact endothelial cell preparations precontracted with NE (10(-7) M) were relaxed by vanadate in a dose dependent manner (from 0.2 to 2 mM). Application of vanadate and ACh during the tonic phase of high K+(100 mM)-induced contraction showed a slight relaxation in contrast to that in NE-induced contraction, but sodium nitroprusside (10 microM) more effectively relaxed the aortic ring preparations in high K+ contraction than that of vanadate. Vanadate-induced relaxation in NE-contracted aortic rings was reversed by application of BaCl2 (50 microM) or glibenclamide (10 microM). Furthermore, Vanadate hyperpolarized membrane potential of smooth muscle cells in endothelium-intact aortic strips and this effect was abolished by application of glibenclamide. The above results suggest that vanadate release EDHF (Endothelium-Derived Hyperpolarizing Factor), in addition to EDRF (Endothelium-Derived Relaxing Factor) from endothelial cell. This EDHF hyperpolarize the smooth muscle cell membrane potential via opening of the ATP-sensitive K+ channel and close a voltage dependent Ca++ channel. So it is suggested that the vanadate-induced relaxation of rabbit thoracic aortic rings may be due to the combined effects of EDRF and EDHF.


Asunto(s)
Conejos , Animales , Aorta/efectos de los fármacos , Técnicas In Vitro , Potenciales de la Membrana/efectos de los fármacos , Potasio/farmacología , Canales de Potasio/fisiología , Compuestos de Tetraetilamonio/farmacología , Vanadatos/farmacología , Vasodilatación/efectos de los fármacos
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