Faculty Collaboration Database

Novel nitric oxide synthase--dependent mechanism of vasorelaxation in small arteries from hypertensive rats. Hypertension 2007 Apr;49(4):893-901

Date

02/21/2007

Pubmed ID

17309950

DOI

10.1161/01.HYP.0000259669.40991.1e

Scopus ID

2-s2.0-34047218002 (requires institutional sign-in at Scopus site)   39 Citations

Abstract

To determine the mechanism(s) involved in vasorelaxation of small arteries from hypertensive rats, normotensive (NORM), angiotensin II-infused (ANG), high-salt (HS), ANG high-salt (ANG/HS), placebo, and deoxycorticosterone acetate-salt rats were studied. Third-order mesenteric arteries from ANG or ANG/HS displayed decreased sensitivity to acetylcholine (ACh)-induced vasorelaxation compared with NORM or HS, respectively. Maximal relaxations were comparable between groups. Blockade of Ca(2+)-activated K(+) channels had no effect on ANG versus blunting relaxation in NORM (log EC(50): -6.8+/-0.1 versus -7.2+/-0.1 mol/L). NO synthase (NOS) inhibition abolished ACh-mediated relaxation in small arteries from ANG, ANG/HS, and deoxycorticosterone acetate-salt versus blunting relaxation in NORM, HS, and placebo (% maximal relaxation: ANG: 2.7+/-1.8; ANG/HS: 7.2+/-3.2; NORM: 91+/-3.1; HS: 82.1+/-13.3; deoxycorticosterone acetate-salt: 35.2+/-17.7; placebo: 79.3+/-10.3), indicating that NOS is the primary vasorelaxation pathway in these arteries from hypertensive rats. We hypothesized that NO/cGMP signaling and NOS-dependent H(2)O(2) maintains vasorelaxation in small arteries from ANG. ACh increased NOS-dependent cGMP production, indicating that NO/cGMP signaling is present in small arteries from ANG (55.7+/-6.9 versus 30.5+/-5.1 pmol/mg), and ACh stimulated NOS-dependent H(2)O(2) production (ACh: 2.8+/-0.2 micromol/mg; N(omega)-nitro-l-arginine methyl ester hydrochloride+ACh: 1.8+/-0.1 micromol/mg) in small arteries from ANG. H(2)O(2) induced vasorelaxation and catalase blunted ACh-mediated vasorelaxation. In conclusion, Ca(2+)-activated K(+) channel-mediated relaxation is dysfunctional in small mesenteric arteries from hypertensive rats, and the NOS pathway compensates to maintain vasorelaxation in these arteries through NOS-mediated cGMP and H(2)O(2) production.

Author List

Kang KT, Sullivan JC, Sasser JM, Imig JD, Pollock JS

MESH terms used to index this publication - Major topics in bold

Acetylcholine
Angiotensin II
Animals
Antioxidants
Aorta
Arteries
Blood Pressure
Cyclic GMP
Drug Combinations
Hydrogen Peroxide
Hypertension
Male
Mesenteric Arteries
Nitric Oxide
Nitric Oxide Synthase
Potassium Channels, Calcium-Activated
Rats
Rats, Sprague-Dawley
Signal Transduction
Sodium Chloride
Vasodilation
Vasodilator Agents