Superoxide constricts rat pulmonary arteries via Rho-kinase-mediated Ca(2+) sensitization

• Published in: Free radical biology & medicine Vol. 46; no. 5; pp. 633 - 642
• Main Authors: Knock, Greg A, Snetkov, Vladimir A, Shaifta, Yasin, Connolly, Michelle, Drndarski, Svetlana, Noah, Anthony, Pourmahram, Ghazaleh E, Becker, Silke, Aaronson, Philip I, Ward, Jeremy P T
• Format: Journal Article
• Language: English
• Published: United States 01.03.2009
• Subjects: Active Transport, Cell Nucleus - drug effects; Amides - pharmacology; Aminoquinolines - pharmacology; Animals; Bronchoconstriction - drug effects; Bronchoconstriction - physiology; Calcium Signaling - physiology; Guanylate Cyclase - antagonists & inhibitors; Hypertension, Pulmonary - enzymology; Hypertension, Pulmonary - pathology; Hypertension, Pulmonary - prevention & control; Indoles - pharmacology; Male; Myocytes, Smooth Muscle - pathology; Myocytes, Smooth Muscle - physiology; Myosin Light Chains - metabolism; Phosphorylation; Protein Phosphatase 1 - metabolism; Pulmonary Artery - pathology; Pyridines - pharmacology; Rats; Rats, Wistar; rho-Associated Kinases - antagonists & inhibitors; rho-Associated Kinases - physiology; src-Family Kinases - antagonists & inhibitors; src-Family Kinases - physiology; Sulfonamides - pharmacology; Superoxides - pharmacology
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2008.11.015

Reactive oxygen species play a key role in vascular disease, pulmonary hypertension, and hypoxic pulmonary vasoconstriction. We investigated contractile responses, intracellular Ca(2+) ([Ca(2+)](i)), Rho-kinase translocation, and phosphorylation of the regulatory subunit of myosin phosphatase (MYPT-1) and of myosin light chain (MLC(20)) in response to LY83583, a generator of superoxide anion, in small intrapulmonary arteries (IPA) of rat. LY83583 caused concentration-dependent constrictions in IPA and greatly enhanced submaximal PGF(2alpha)-mediated preconstriction. In small femoral or mesenteric arteries of rat, LY83583 alone was without effect, but it relaxed a PGF(2)alpha-mediated preconstriction. Constrictions in IPA were inhibited by superoxide dismutase and tempol, but not catalase, and were endothelium and guanylate cyclase independent. Constrictions were also inhibited by the Rho-kinase inhibitor Y27632 and the Src-family kinase inhibitor SU6656. LY83583 did not raise [Ca(2+)](i), but caused a Y27632-sensitive constriction in alpha-toxin-permeabilized IPA. LY83583 triggered translocation of Rho-kinase from the nucleus to the cytosol in pulmonary artery smooth muscle cells and enhanced phosphorylation of MYPT-1 at Thr-855 and of MLC(20) at Ser-19 in IPA. This enhancement was inhibited by superoxide dismutase and abolished by Y27632. Hydrogen peroxide did not activate Rho-kinase. We conclude that in rat small pulmonary artery, superoxide triggers Rho-kinase-mediated Ca(2+) sensitization and vasoconstriction independent of hydrogen peroxide.