异丙酚对表达在HEK293细胞上的大电导钙激活钾(BKCa)通道的作用

Effects of propofol on large conductance Ca^(2+)-activated K^+(BK_(Ca)) channels expressed in HEK293 Cells

目的:研究异丙酚对表达在HEK293细胞上的BK_(Ca)通道的作用,探讨异丙酚降低血压的作用机制。方法:将含有人血管平滑肌BK_(Ca)通道α亚单位(h Slo1)的表达质粒pc DNA3.1-h Slo1使用脂质体转染法(lipofectamine 2000)转染至培养的HEK293细胞,使用膜片钳全细胞和单通道记录方式研究异丙酚对BK_(Ca)通道的作用。结果:在全细胞构型下,56μM异丙酚能够明显增加BK_(Ca)宏观电流(P<0.01或P<0.05),在膜电位(Vm)为+60 mV时,56μM异丙酚明显增加BK_(Ca)宏观电流密度(87.29±7.10 pA/pF到131.21±9.68 pA/p F,n=6),两组相比,差异具有统计学意义(P<0.01)。在内面向外式膜片下,56μM异丙酚能够明显增加BK_(Ca)单通道开放概率(0.015±0.002到0.066±0.013,n=10),两组相比,差异具有统计学意义(P<0.01)。结论:异丙酚能够明显激活表达在HEK293细胞上的BK_(Ca)通道,BK_(Ca)通道的激活可能参与了异丙酚介导的血管舒张。

Objective： Large conductance calcium activated potassium （BKca） channels play a crucial role in tension regulation of vascular smooth muscle. Here, we aim to investigate the effects of propofol on BKCa channels expressed in HEK293 and the underlying mechanisms of propofol-mediated vascular relaxation. Methods： Plasmid pcDNA3.1-hSlol encoding human BKCa channels ct subunit （hSlol） was transfected into HEK293 cells using Lipofectamine 2000 and the effects of propofol on BKca currents were analyzed with patch clamp techniques in whole-cell and single channel recording respectively. Results： In the whole cell configuration, 56μM propofot significantly increased BKca macroscopic currents at different membrane voltages （Vm） （P 〈 0. 01 or P 〈 0.05）. At Vm= ＋ 60 mV, 56μM propofol significantly increased BKCa current density from 87.29±7.10 pA/pF to 131.21±9.68 pA/pF （P 〈 0.01, n = 6）. Under inside-out configuration, 56μM propofol significantly increased single BKCa channel total open probability （NPo） from 0.015±0.002 to 0.066±0.013 （P 〈 0.01, n = 10）. Conclusions： Propofol significantly activated BKca channels expressed in HEK293 cells, suggesting that activation of BKCa channels may be involved in the propofol-mediated dilation of blood vessels. Keywords Propofol; BKCa channels; Vascular tension; Gene transfection