钙激活钾通道在烟雾暴露所致大鼠血压升高中的作用

Effect of Calcium-activated Potassium Channels in Vascular Smooth Muscle on Hypertension Induced by Cigarette Smoking in Rats

目的:观察烟雾暴露对大鼠血压水平及主动脉血管平滑肌细胞(VSMC)大电导钙激活钾通道(BK通道)电流的影响。方法:3周龄雄性Wister大鼠随机分为2组:对照组和烟雾暴露组,每组24只大鼠;对照组予以正常环境下饲养,烟雾暴露组置于自制的实验性大鼠被动吸烟箱内进行被动吸烟。采用尾动脉测压法测量大鼠血压,HE染色观察血管壁结构,全细胞膜片钳技术记录大鼠主动脉VSMC膜BK电流。结果:烟雾暴露组大鼠血压从第8周开始明显升高,随着烟雾暴露时间延长,血压逐渐升高;在第10、12周时血压较对照组均显著升高(P<0.05)。烟雾暴露组大鼠主动脉血管壁局部增厚,内膜内皮细胞层下基质部分变厚,有核细胞增多,平滑肌层增厚,平滑肌细胞整体变短小,对照组大鼠主动脉血管壁形态无明显变化;烟雾暴露组大鼠主动脉VSMC膜BK电流和电流密度随烟雾暴露时间延长而显著降低;在第8、12周时,BK峰电流密度较对照组明显降低,差异有统计学意义(P<0.05)。结论:烟雾暴露可导致大鼠主动脉血管壁形态改变,并引起血压升高;大鼠BK电流密度随着烟雾暴露时间延长而逐渐降低。

Objective:To observe the effects of smoke exposure on blood pressure levels and large-conductance calcium-activated potassium channels(BK channels)in aortic vascular smooth muscle cells(VSMC)in rats.Methods:Three-week-old male wister rats were divided into control group and smoke exposure group randomly,24 rats in each group.Rats in the control group were kept in normal environment,and rats in the smoke exposure group were placed in experimental rat passive smoking box.Blood pressure was measured by tail artery manometry,HE staining was used to observe the structure of blood vessel wall,and whole cell patch clamp technique was used to record BK current in rat aorta VSMC membrane.Results:Blood pressure of the rats in smoke exposure group increased significantly at the 8th week.The blood pressure increased with the prolonged exposure time of smoking gradually.At the 10th and 12th week,the blood pressure in smoke exposure group was significantly higher than that in control group(P<0.05).In the smoke exposed group,the aortic wall of the rats in smoke exposure group were thickened locally,the stromal of the endometrial endothelial cells became thicker,the nucleated cells increased,the smooth muscle layer thickened,and the smooth muscle cells became shorter.The aortic wall morphology of the control rats was not changed.The BK current and current density of the VSMC membrane of the aorta in the smoke exposure group were decreased with the extension of the smoke exposure time significantly.At the 8th and 12th week,the BK peak current density was lower than that of the control group significantly(P<0.05).Conclusion:Smoke exposure can cause changes in the morphology of rat aortic wall and increase blood pressure.The current density of BK channels in rats decreases gradually with the extension exposure time of smoke.