Effects of vanadate on vascular contractility and membrane potential in the rabbit aorta
Yonsei Medical Journal
; : 14-23, 1992.
Article
in En
| WPRIM
| ID: wpr-153235
Responsible library:
WPRO
ABSTRACT
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.
Key words
Full text:
1
Index:
WPRIM
Main subject:
Aorta
/
Potassium
/
Vasodilation
/
In Vitro Techniques
/
Vanadates
/
Potassium Channels
/
Tetraethylammonium Compounds
/
Animals
/
Membrane Potentials
Limits:
Animals
Language:
En
Journal:
Yonsei Medical Journal
Year:
1992
Type:
Article