Abstract
Evidence indicates that both the Rho/Rho kinase signaling pathway and reactive oxygen species (ROS) such as superoxide and H2O2 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 μ) 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 Ca2+-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 Ca2+ sensitization is through activation of Rho and a subsequent increase in Rho kinase activity but not Ca2+-independent PKC.
Original language | English (US) |
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Pages (from-to) | H1495-H1500 |
Journal | American Journal of Physiology - Heart and Circulatory Physiology |
Volume | 287 |
Issue number | 4 56-4 |
DOIs | |
State | Published - Oct 2004 |
Externally published | Yes |
Keywords
- Antioxidants
- Myosin light chain phosphatase
- Smooth muscle contraction
ASJC Scopus subject areas
- Physiology
- Cardiology and Cardiovascular Medicine
- Physiology (medical)