The Role of Oxygen-Derived Free Radicals in Vascular Relaxations to Pinacidil in Renal Hypertensive Rats

Korean Journal of Nephrology 2010;29(6):695-701.

Seok Choi, Ph.D.1, Im Joon Yoo, M.D.1, Hee Wook Whi, M.D.1, Jae Yeoul Jun, M.D.1, Hyun Il Kim, M.D.2, Hye Rang Shin, M.D.2, Hyun Jung Oh, M.D.2, Jong Hoon Chung, M.D.3 and Cheol Ho Yeum, Ph.D.1

Department of Physiology¹
Psychiatry2 and Internal Medicine³
College of Medicine, Chosun University, Gwangju, Korea

원저 : 신성 고혈압 쥐에서 Pinacidil에 의한 혈관 이완반응에 있어 산소유리기의 역할

최석1, 유임준1, 위희욱1, 전제열1, 김현일2, 신혜랑2, 오현정2, 정종훈3, 염철호1

조선대학교 의과대학 생리학교실1, 정신과학교실2, 내과학교실3

Abstract

Purpose: Evidence has emerged that oxygen-derived free radicals may induce vascular relaxations via ATP-sensitive K+ (KATP) channels and the level of free radicals is increased in animal models of hypertension. The present study was conducted to determine whether relaxations to an KATP channel opener, pinacidil, are increased in the aorta from two-kidney, one clip (2K1C) hypertensive rats and whether free radial scavengers reduce these relaxations. Methods: 2K1C hypertension was induced by clipping the left renal artery and age-matched control rats received a sham treatment. Rings of aortae without endothelium were suspended for isometric force recording. Results: Relaxations to pinacidil (10-8 to 10-5 M), which are abolished by glibenclamide (10-5 M), were augmented in the aorta from 2K1C rats, compared to those from control rats. In the aorta from 2K1C rats, catalase (1,200 U/mL), but neither superoxide dismutase (150 U/mL) nor deferoxamine (10-4 M), reduced relaxations to pinacidil, whereas in the aorta from control rats, the free radical scavengers did not affect these relaxations. Conclusion: These results suggest that in 2K1C hypertension, vasorelaxation to an KATP channel opener is augmented and that hydrogen peroxide in smooth muscle cells may partly contribute to these relaxations.

Key Words: KATP channels, Hydrogen peroxide, Vasorelaxation, Renal hypertension