Activation of Rho/Rho kinase signaling pathway by reactive oxygen species in rat aorta

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 287; no. 4; pp. H1495 - H1500
• Main Authors: Jin, Liming, Ying, Zhekang, Webb, R. Clinton
• Format: Journal Article
• Language: English
• Published: United States 01.10.2004
• Subjects: Amides - pharmacology; Animals; Aorta - metabolism; Enzyme Inhibitors - pharmacology; Intracellular Signaling Peptides and Proteins; Male; Muscle Contraction - physiology; Muscle, Smooth, Vascular - enzymology; Myosin-Light-Chain Phosphatase - metabolism; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Serine-Threonine Kinases - metabolism; Pyridines - pharmacology; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species - metabolism; rho GTP-Binding Proteins - metabolism; rho-Associated Kinases; Signal Transduction - physiology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01006.2003

Department of Physiology, Medical College of Georgia, Augusta, Georgia 30912-3000 Submitted 23 October 2003 ; accepted in final form 26 May 2004 Evidence indicates that both the Rho/Rho kinase signaling pathway and reactive oxygen species (ROS) such as superoxide and H 2 O 2 are involved in the pathogenesis of hypertension. This study aimed to determine whether ROS-induced vascular contraction is mediated through activation of Rho/Rho kinase. Rat aortic rings (endothelium denuded) were isolated and placed in organ chambers for measurement of isometric force development. ROS were generated by a xanthine (X)-xanthine oxidase (XO) mixture. The antioxidants tempol (3 mM) and catalase (1,200 U/ml) or the XO inhibitor allopurinol (400 µM) significantly reduced X/XO-induced contraction. A Rho kinase inhibitor, (+)-( R )- trans -4-(1-aminoethyl- N -4-pyridil)cyclohexanecarboxamide dihydrochloride (Y-27632), decreased the contraction in a concentration-dependent manner; however, the Ca 2+ -independent protein kinase C inhibitor rottlerin did not have an effect on X/XO-induced contraction. Phosphorylation of the myosin light chain phosphatase target subunit (MYPT1) was increased by ROS, and preincubation with Y-27632 blocked this increased phosphorylation. Western blotting for cytosolic and membrane-bound fractions of Rho showed that Rho was increased in the membrane fraction by ROS, suggesting activation of Rho. These observations demonstrate that ROS-induced Ca 2+ sensitization is through activation of Rho and a subsequent increase in Rho kinase activity but not Ca 2+ -independent PKC. myosin light chain phosphatase; smooth muscle contraction; antioxidants Address for reprint requests and other correspondence: L. Jin, Dept. of Physiology, Medical College of Georgia, 1120 15th St., Augusta, GA 30912-3000 (E-mail: ljin{at}mcg.edu )