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
King's College London, UK.
Free Radic Biol Med. 2009 Mar 1;46(5):633-42. doi: 10.1016/j.freeradbiomed.2008.11.015. Epub 2008 Dec 6.
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+)), 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+), 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.
活性氧在血管疾病、肺动脉高压和低氧性肺血管收缩中起关键作用。我们研究了在大鼠肺内小动脉（IPA）中，超氧阴离子生成剂LY83583对收缩反应、细胞内Ca(2+)（Ca(2+)）、Rho激酶易位以及肌球蛋白磷酸酶调节亚基（MYPT-1）和肌球蛋白轻链（MLC(20)）磷酸化的影响。LY83583在IPA中引起浓度依赖性收缩，并极大增强了次最大剂量PGF(2α)介导的预收缩。在大鼠股动脉或肠系膜小动脉中，单独使用LY83583无作用，但它可舒张PGF(2α)介导的预收缩。IPA中的收缩被超氧化物歧化酶和tempol抑制，但不被过氧化氢酶抑制，且与内皮和鸟苷酸环化酶无关。收缩也被Rho激酶抑制剂Y27632和Src家族激酶抑制剂SU6656抑制。LY83583未升高Ca(2+)，但在α-毒素通透的IPA中引起Y27632敏感的收缩。LY83583触发Rho激酶从肺动脉平滑肌细胞核向细胞质易位，并增强IPA中MYPT-1在Thr-855位点和MLC(20)在Ser-19位点的磷酸化。这种增强被超氧化物歧化酶抑制，并被Y27632消除。过氧化氢未激活Rho激酶。我们得出结论，在大鼠小肺动脉中，超氧化物触发Rho激酶介导的Ca(2+)致敏和血管收缩，且不依赖于过氧化氢。
