拉马克啉对缺氧培养的肺动脉内皮及平滑肌细胞的影响及其机制探讨

目的:探讨三磷酸腺苷(ATP)敏感钾通道开放剂拉马克啉(Lev)对缺氧条件下培养的肺动脉内皮(PAEC)及平滑肌细胞(PASMC)的影响及其可能的作用机制。方法:分析Lev对缺氧条件下培养的PAEC及PASMC的Ca²⁺]_i、上清液中NO^-₂及ET-1水平、细胞内PKC_α、eNOS、iNOS及PDGF-B的mRNA和蛋白质水平及PASMC增殖和凋亡的影响及其作用的细胞内机制。结果:①Lev可降低缺氧时PASMC及PAEC上清液中ET-1及细胞内PKC_α、iNOS及PDGF-B的mRNA和蛋白质水平,可降低PASMCCa²⁺]_i,抑制PASMC增殖,促其凋亡(P均<0.05),而对PAECCa²⁺]_i及PASMC、PAEC上清液中NO^-₂水平及细胞内eNOS的mRNA和蛋白质水平无明显影响(P均>0.05)。②Lev下调缺氧时PASMC及PAEC上清液中ET-1水平及PASMC增殖的机制涉及抑制缺氧时PKC_α信号通道的功能活性。结论:Lev可减轻缺氧对PAEC及PASMC的某些不利影响,其作用的部分机制涉及下调缺氧时PAEC及PASMC内PKC_α信号通道的功能活性和降低PASMC的Ca²⁺]_i,而与eNOS-NO信号通道无关。

Effects of levcromakalim on pulmonary arterial endothelial cells and smooth muscle cells exposed to hypoxia

AIM:To explore the effects of levcromakalim(Lev) on pulmonary arterial endothelial cells (PAEC) and smooth muscle cells (PASMC) exposed to hypoxia and the mechanisms involved.METHODS:The effects of Lev on Ca²⁺]_i, and expression of PKC_α, eNOS, iNOS and PDGF-B mRNA and protein levels were observed. The nitrite (NO₂^-) and entothelin-1(ET-1) concentrations in supernatant in cultured PAEC and PASMC were measured. The proliferation and apoptosis of PASMC was also detected.RESULTS:When PASMC were exposed to hypoxia, Lev reduced concentration of ET-1 in cultured cell supernatant, lowed the expression of PKC_α, iNOS and PDGF-B both at mRNA and protein levels, decreased Ca²⁺]_i concentration, increased proliferation and promoted the apoptosis in PASMC. However, in the presence of Lev, the Ca²⁺]_i concentration was not changed in the hypoxic PAEC. The NO₂^- concentration in cultured cell supernant and expression of eNOS at mRNA and protein levels in hypoxic PASMC and PAEC were also unchanged. The downregulated ET-1 activity in PASMC and PAEC and proliferation in PASMC involved in the inhibition of PKC_α signaling pathway.CONCLUSIONS:Lev reduce some disadvatage effect of hypoxia on PASMC and PAEC. The mechanism of Lev action may partly involve in the downregulation of PKC_α signaling functions.