Reactive oxygen species are involved in regulating α1- adrenoceptor-activated vascular smooth muscle contraction

Ming Ho Tsai, Meei Jyh Jiang

研究成果: Article同行評審

31 引文 斯高帕斯(Scopus)


Background. 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 α1-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 1-adrenoceptor agonist phenylephrine were examined. Results. An antioxidant, N-acetyl-L-cysteine (NAC), and two NADPH oxidase inhibitors, apocynin and VAS2870, dose-dependently inhibited contraction activated by phenylephrine. Phenylephrine stimulated superoxide anion production that was diminished by the pretreatment of apocynin, VAS2870, superoxide scavenger tiron or mitochondria inhibitor rotenone, but not by xanthine oxidase inhibitor allopurinol or cyclooxygenase inhibitor indomethacin. Concurrently, NADPH oxidase activity in RTA homogenates increased within 1 min upon phenylephrine stimulation, sustained for 10 min, and was abolished by the co-treatment with apocynin, but not allopurinol or rotenone. Phenylephrine-induced MLC20phosphorylation was dose-dependently decreased by apocynin. Furthermore, apocynin inhibited phenylephrine-stimulated RhoA translocation to plasma membrane and phosphorylation of both myosin phosphatase regulatory subunit MYPT1Thr855 and myosin phosphatase inhibitor CPI-17Thr38. Conclusions. ROS, probably derived from NADPH oxidase and mitochondria, partially regulate α1-adrenoceptor- activated smooth muscle contraction by altering myosin phosphatase-mediated MLC20phosphorylation through both RhoA/Rho kinase- and CPI-17-dependent pathways.

期刊Journal of biomedical science
出版狀態Published - 2010

All Science Journal Classification (ASJC) codes

  • 內分泌學、糖尿病和代謝
  • 分子生物學
  • 臨床生物化學
  • 細胞生物學
  • 生物化學(醫學)
  • 藥學(醫學)


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