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Updated: Aug 15, 2026

Standardized Rat Coronary Ring Preparation and Real-Time Recording of Dynamic Tension Changes Along Vessel Diameter
Published on: June 16, 2022
Peroxynitrite hyperpolarizes smooth muscle and relaxes internal carotid artery in rabbit via ATP-sensitive K+
Masuo Ohashi1, Frank Faraci, Donald Heistad
1Cardiovascular Center and Dept. of Internal Medicine, Univ. of Iowa and Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242-1801, USA.
Abstract:
The goal of this study was to determine the effects of peroxynitrite (ONOO-) on smooth muscle membrane potential and vasomotor function in rabbit carotid arteries. ONOO- is known to affect vascular tone by several mechanisms, including effects on K+ channels. Xanthine (X, 0.1 mM), xanthine oxidase (XO, 0.01 U/ml), and a low concentration of sodium nitroprusside (SNP, 10 nM) were used to generate ONOO-. In the common carotid artery, X and XO (X/XO) in the presence of SNP tended to increase tension. In contrast, in the internal carotid artery, X/XO in the presence of SNP transiently hyperpolarized the membrane (-8.5 +/- 1.8 mV, mean +/- SE) and decreased tension (by 85 +/- 5.6%). In internal carotid arteries, in the absence of SNP, X/XO did not hyperpolarize the membrane and produced much less relaxation (by 23 +/- 5.6%) than X/XO and SNP. Ebselen (50 microM) inhibited both hyperpolarization and relaxation to X/XO and SNP, and uric acid (100 microM) inhibited relaxation. Glibenclamide (1 microM) abolished hyperpolarization and inhibited relaxation during X/XO and SNP. Charybdotoxin (100 nM) or tetraethylammonium (1 mM) did not affect hyperpolarization or relaxation, respectively. These results suggest that ONOO- hyperpolarizes and relaxes smooth muscle in rabbit internal carotid artery but not in common carotid artery through activation of K(ATP) channels.
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