Korean J Nephrol.  2010 Nov;29(6):695-701.

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

• Choi S
• Yoo IJ
• Whi HW
• Jun JY
• Kim HI
• Shin HR
• Oh HJ
• Chung JH
• Yeum CH

Abstract

PURPOSE
Evidence has emerged that oxygen-derived free radicals may induce vascular relaxations via ATP-sensitive K+ (K(ATP)) 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 K(ATP) 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.

Keyword

K(ATP) channels; Hydrogen peroxide; Vasorelaxation; Renal hypertension

MeSH Terms

Animals
Aorta
Catalase
Deferoxamine
Endothelium
Free Radical Scavengers
Free Radicals
Glyburide
Hydrogen Peroxide
Hypertension
Hypertension, Renal
Models, Animal
Myocytes, Smooth Muscle
Pinacidil
Placebos
Rats
Relaxation
Renal Artery
Salicylamides
Superoxide Dismutase
Vasodilation
Catalase
Deferoxamine
Free Radical Scavengers
Free Radicals
Glyburide
Hydrogen Peroxide
Pinacidil
Placebos
Salicylamides
Superoxide Dismutase