二十二碳六烯酸对大鼠肺动脉平滑肌细胞大电导钙激活性钾通道的影响

Effects of docosahexaenoic acid on large-conductance calcium-activated potassium channels in rat pulmonary artery smooth muscle cells

目的:探讨二十二碳六烯酸(DHA)对大鼠肺动脉平滑肌细胞(PASMCs)大电导钙激活性钾离子通道(BKCa)的作用。方法:采用酶解法获得单个活性良好的PASMC,PASMCs的BKCa电流变化采用全细胞膜片钳技术记录,PASMCs胞浆内游离钙离子浓度([Ca2+]i)采用激光共聚焦显微镜技术测定。结果:DHA 0.01μmol/L对BKCa无显著激活作用;0.1、1、10μmol/L DHA可显著激活BKCa。不同浓度的DHA(0、0.1、1、10μmol/L)在指令电压为+60 mV时,BKCa电流密度分别为(30.5±6.5)pA/pF、(59.4±5.8)pA/pF、(87.2±4.3)pA/pF和(117.3±7.1)pA/pF(P<0.01)。急性缺氧在指令电压为+60 mV时,BKCa电流密度从(32.7±8.5)pA/pF降低至(11.9±5.8)pA/pF(P<0.01)。DHA(10μmol/L)能明显逆转急性缺氧对BKCa的抑制作用(P<0.01),同时DHA触发PASMCs内[Ca2+]i的增加,最大增加速率为(71.9±4.1)%(P<0.01)。结论:DHA通过增加PASMCs[Ca2+]i激活BKCa,逆转急性缺氧对BKCa的抑制作用,具有舒张肺血管的作用。

AIM： To investigate the effects of docosahexaenoic acid（DHA） on large-conductance calcium-activated potassium channels（BKCa） in rat pulmonary artery smooth muscle cells（PASMCs）.METHODS： BKCa currents in individual PASMCs were recorded by patch-clamp technique in whole-cell configuration.Calcium sparks in PASMCs caused by DHA were recorded by confocal microscopy.RESULTS： DHA activated BKCa.BKCa current densities were（30.5 ± 6.5） pA / pF,（59.4 ± 5.8） pA / pF,（87.2 ± 4.3） pA / pF and（117.3 ± 7.1） pA / pF（P 0.01） with the addition of DHA at concentrations of 0,0.1,1 and 10 μmol / L,respectively.Hypoxia inhibited BKCa currents in PASMCs,but this inhibition was reversed by DHA（10 μmol / L）.DHA（10 μmol / L） induced an increase in [Ca2 ＋]i with a maximal increase rate of（71.9 ± 4.1） %.CONCLUSION： DHA activates BKCa in rat PASMCs,leading to the vasodilation of pulmonary arteries.