Nitric oxide attenuates insulin- or IGF-I-stimulated aortic smooth muscle cell motility by decreasing H2O2 levels: essential role of cGMP

• Published in: American journal of physiology. Heart and circulatory physiology 2004-06, Vol.286 (6), p.H2103
• Main Authors: Zhuang, Daming, Ceacareanu, Alice-Corina, Lin, Yi, Ceacareanu, Bogdan, Dixit, Madhulika, Chapman, Kenneth E, Waters, Christopher M, Rao, Gadiparthi N, Hassid, Aviv
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Antioxidants - metabolism; Aorta, Thoracic - cytology; Catalase - metabolism; Cell Movement - drug effects; Cell Movement - physiology; Cells, Cultured; Cyclic GMP - metabolism; Enzyme Activation - drug effects; Enzyme Inhibitors - pharmacology; Female; Guanylate Cyclase - antagonists & inhibitors; Hydrogen Peroxide - metabolism; Hydrogen Peroxide - pharmacology; Hypoglycemic Agents - pharmacology; Insulin - pharmacology; Insulin-Like Growth Factor I - pharmacology; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; NADPH Oxidases - metabolism; Nitric Oxide - metabolism; Oxadiazoles - pharmacology; Oxidants - metabolism; Oxidants - pharmacology; Phosphorylation - drug effects; Protein-Serine-Threonine Kinases; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-akt; Quinoxalines - pharmacology; Rats; Rats, Sprague-Dawley
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01118.2003

Department of Physiology and Vascular Biology Center, University of Tennessee Health Science Center, Memphis, Tennessee 38163 Submitted 24 November 2003 ; accepted in final form 23 January 2004 Insulin and insulin-like growth factor I (IGF-I) both play important roles in vascular remodeling. Moreover, nitric oxide (NO) is well established as a counterregulatory agent that opposes the actions of several vascular agonists, in part by decreasing smooth muscle motility. We tested the hypothesis that NO blocks insulin or IGF-I-induced rat aortic smooth muscle cell motility via a mechanism involving the attenuation of agonist-induced elevation of hydrogen peroxide levels and cGMP as mediator. Insulin or IGF-I induced an increase of hydrogen peroxide levels and cell motility. Both effects were blocked by catalase or diphenyleneiodonium, indicating that hydrogen peroxide elevation is necessary for induction of cell motility. Two NO donors mimicked the effects of catalase, indicating that NO decreases cell motility by suppressing agonist-induced elevation of hydrogen peroxide. A cGMP analogue mimicked the effect of NO, whereas a guanyl cyclase inhibitor blocked the effect of NO on hydrogen peroxide levels, indicating that elevation of cGMP is both necessary and sufficient to account for the reduction of hydrogen peroxide levels. A NO donor as well as a cGMP analogue attenuated insulin-stimulated NADPH activity, indicating that NO decreases hydrogen peroxide levels by inhibiting the generation of superoxide, via a cGMP-mediated mechanism. Finally, exogenous hydrogen peroxide increased cell motility and reversed the inhibitory effect of cGMP. These results support the view that NO plays an antioxidant role via reduction of hydrogen peroxide in cultured rat aortic smooth muscle cells and that this effect is both necessary and sufficient to account for its capacity to decrease cell motility. vascular remodeling; antioxidant; Akt; NAD(P)H oxidase Address for reprint requests and other correspondence: A. Hassid, Dept. of Physiology, Univ. of Tennessee Heath Science Center, Memphis, TN 38103 (E-mail: ahassid{at}tennessee.edu ).