Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College London, Room 3.20, Franklin Wilkins Building, Stamford Street, London SE1 9NH, UK.
Cardiovasc Res. 2011 Jan 1;89(1):214-24. doi: 10.1093/cvr/cvq275. Epub 2010 Aug 30.
the aim of this study was to determine the relative importance of Ca(2+) sensitization, ion channels, and intracellular Ca(2+) (Ca(2+)) in the mixed constrictor/relaxation actions of superoxide anion on systemic and pulmonary arteries.
pulmonary and mesenteric arteries were obtained from rat. Superoxide was generated in arteries and cells with 6-anilino-5,8-quinolinequinone (LY83583). Following pre-constriction with U46619, 10 μmol/L LY83583 caused constriction in pulmonary and relaxation in mesenteric arteries. Both constrictor and relaxant actions of LY83583 were inhibited by superoxide dismutase and catalase. LY83583 caused Rho-kinase-dependent constriction in α-toxin-permeabilized pulmonary but not mesenteric arteries. Phosphorylation of myosin phosphatase-targeting subunit-1 (MYPT-1; as determined by western blot), was enhanced by LY83583 in pulmonary artery only. However, in both artery types, changes in tension were closely correlated with changes in phosphorylation of the 20 kDa myosin light chain as well as changes in Ca(2+) (as measured with Fura PE-3), with LY83583 causing increases in pulmonary and decreases in mesenteric arteries. When U46619 was replaced by 30 mmol/L K(+), all changes in Ca(2+) were abolished and LY83583 constricted both artery types. The K(V) channel inhibitor 4-aminopyridine abolished the LY83583-induced relaxation in mesenteric artery without affecting constriction in pulmonary artery. However, LY83583 caused a similar hyperpolarizing shift in the steady-state activation of K(V) current in isolated smooth muscle cells of both artery types.
superoxide only causes Rho-kinase-dependent Ca(2+) sensitization in pulmonary artery, resulting in constriction, and whilst it opens K(V) channels in both artery types, this only results in relaxation in mesenteric.
本研究旨在确定超氧阴离子对体肺血管混合收缩/舒张作用中钙敏化、离子通道和细胞内钙(Ca(2+))的相对重要性。
从大鼠中获得肺和肠系膜动脉。用 6-苯胺-5,8-喹啉二酮（LY83583）在血管和细胞中生成超氧阴离子。在 U46619 预收缩后，10 μmol/L LY83583 引起肺血管收缩和肠系膜血管舒张。超氧化物歧化酶和过氧化氢酶均能抑制 LY83583 的收缩和舒张作用。LY83583 在α-毒素通透的肺血管中引起 Rho-激酶依赖性收缩，但在肠系膜血管中则不然。仅在肺血管中，LY83583 增强肌球蛋白磷酸酶靶向亚单位-1（MYPT-1；通过western blot 测定）的磷酸化。然而，在两种血管类型中，张力的变化与 20 kDa 肌球蛋白轻链的磷酸化变化以及Ca(2+)的变化（用 Fura PE-3 测量）密切相关，LY83583 引起肺血管收缩和肠系膜血管舒张。当 U46619 被 30 mmol/L K(+)取代时，所有Ca(2+)的变化均被消除，LY83583 收缩两种血管类型。K(V)通道抑制剂 4-氨基吡啶消除了 LY83583 引起的肠系膜动脉舒张作用，而不影响肺血管的收缩作用。然而，LY83583 引起两种血管类型的平滑肌细胞中 K(V)电流稳态激活的类似超极化偏移。
超氧阴离子仅在肺血管中引起 Rho-激酶依赖性钙敏化，导致收缩，并且尽管它在两种血管类型中打开 K(V)通道，但这仅导致肠系膜舒张。
