Altered Vascular Response to the K+induced Vasorelaxation in Aortic Smooth Muscle of Renal Hypertensive Rats.
10.4070/kcj.2000.30.8.980
- Author:
Jae Yeoul JUN
;
Cheol Ho YEUM
;
Pyung Jin YOON
;
Jeong Hoe LIEE
;
Hyung Ho CHOI
;
Yoo Whan PARK
;
Jin Ho KIM
- Publication Type:Original Article
- Keywords:
K+induced relaxation;
Ouabain
- MeSH:
4-Aminopyridine;
Animals;
Aorta;
Barium;
Baths;
Cesium;
Glyburide;
Hypertension;
Muscle, Smooth*;
Ouabain;
Phenylephrine;
Placebos;
Rats*;
Relaxation;
Renal Artery;
Tetraethylammonium;
Vasodilation*
- From:Korean Circulation Journal
2000;30(8):980-988
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
BACKGROUND: An increase of the extracellular K+concentrations up to about 8 mM in the isolated vessels causes relaxation in pre-contracted state. In order to elucidate the mechanisms of K+induced relaxation and compare with that of 2-kidney, 1 clip (2K1C) renal hypertensive rats, we recorded aortic vascular tension using an organ bath study. METHOD: 2K1C hypertension was made by clipping the left renal artery and age-matched control rats received a sham treatment. Thoracic aortic rings were mounted in tissue baths for measurement of isometric contractile force. RESULTS: Exposure to K+(from 2 to 8 mM) relaxed a phenylephrine (2 x 10-6 M)-induced contraction in K+free Krebs-Ringer solution, dose-dependently. Ouabain (10-5 M) enhanced the K+induced relaxation in above 2 mM K+ The K+induced relaxation was still induced in endothelium-denuded condition. Incubation with the K+channel blockers such as tetraethylammonium (TEA, 1 mM), glibenclamide (10-5 M), 4-aminopyridine (3 mM), barium (5 mM) and cesium (2 mM) did not affect on the K+induced relaxation. In renal hypertensive rats, the K+induced relaxation was markedly suppressed and ouabain enhanced it. CONCLUSIONS: These results suggest that the K+induced relaxation in aorta be mediated by Na-pump independent mechanisms, and the decrease of the K+induced relaxation in the renal hypertensive rats may be a possible mechanism of hypertension.
