Reactive oxygen species are involved in regulating a1-adrenoceptor-activated vascular smooth muscle contraction

Reactive oxygen species (ROS) were shown to mediate aberrant contractility in hypertension, yet the physiological roles of ROS in vascular smooth muscle contraction have remained elusive. This study aimed to examine whether ROS regulate a1-adrenoceptor-activated contraction by altering myosin phosphatase activities. Methods: Using endothelium-denuded rat tail artery (RTA) strips, effects of anti-oxidants on isometric force, ROS production, phosphorylation of the 20-kDa myosin light chain (MLC20), and myosin phosphatase stimulated by a1-adrenoceptor agonist phenylephrine were examined. Results: An antioxidant, N-acetyl-L-cysteine (NAC), and two NADPH oxidase inhibitors, apocynin and VAS2870,...