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目的 探讨高血压心脏功能的变化与小电导钙激活钾通道(SK)的关系.方法 自发性高血压大鼠作为实验组(雄性,n=15),SKY大鼠作为对照组(雄性,n=11),采用尾套法和标准Ⅱ导联测定2组大鼠的动脉血压(ABP)和心电图;采用免疫印迹检测2组大鼠心脏组织SK2通道蛋白的表达;采用免疫细胞化学观察实验组大鼠心房和心室细胞SK2通道的分布.结果 与对照组比较,实验组大鼠血压明显升高[(161.91±2.15)mmHg比(109.67±2.65)mmHg(1 mmHg=0.133 kPa),P＜0.05)],P波时长和R-R间期延长[P波:(29.27±0.74) ms比(26.60±0.24)ms,R-R间期(161.64±8.78)ms比(131.40±1.65)ms,均P＜0.05],而QRS波长和P-R间期与对照组相比差异无统计学意义.与对照组比较,实验组大鼠心房组织SK2蛋白表达降低(P＜0.05),心室组织SK2蛋白表达量与对照鼠差异无统计学意义.SK2通道分布于高血压大鼠心房细胞膜,心室细胞的SK2阳性免疫反应略弱.结论 自发性高血压大鼠心脏SK2通道表达下调.

Objective To investigate the relationship between small conductance calcium-activated potassium channels (SK) and the cardiac function in hypertension.Methods Fifteen spontaneously hypertensive rats (SHR,male,n=15) as test group and 11 male Wistar-Kyoto (WKY) rats as controls were used in this study.In these groups,arterial blood pressure (ABP) was measured with tail-trussed method and ECG was recorded using standard lead Ⅱ.Expression of SK2 protein in myocardium of the rats was determined by Western blotting analysis.The distribution of SK2 channels both in rat atrial and ventricular tissues was observed with immunohistochemistry.Results Compared with controls,the SHR had significantly increased ABP [(161.91±2.15) mmHg vs (109.67±2.65) mmHg,1 mmHg=0.133 kPa,P＜ 0.05],longer P wave duration [(29.27±0.74)ms vs (26.60±0.24)ms,P＜0.05]and prolonged R-R interval [(161.64±8.78)ms vs (131.40± 1.65)ms,P＜0.05)].The QRS duration and P-R interval did not differ between SHR and the controls (P＞0.05).The level of SK2 expression in atrial tissue was lowered in SHR than that in the controls (P＜0.05),but the SK2 expression in ventricular tissues did not differ between the two groups.In SHR,distribution of SK2 channels was chiefly localized on the membrane of atrial cells,in contrast to the weak positive response of SK2 staining in ventricular cells by immunohistochemistry.Conclusions The expression of the SK2 channel is down-regulated in the hearts of spontaneously hypertensive rats.