【摘要】 目的观察自发性高血压大鼠(spontaneous hypertensive rats,SHR)与Wistar-Kyoto(WKY)大鼠肠系膜动脉血管平滑肌细胞(vascular smooth muscle cells,VSMCs)大电导钙激活钾通道(large conductance calcium-activated po-tassiumchannel,BKCa)电流及通道α亚单位表达的差异。方法实验采用16～18周龄SHR(N=20)及WKY(N=20)大鼠,尾套法测量大鼠尾动脉血压;胶原酶分离VSMCs,全细胞膜片钳技术记录全细胞总钾电流密度及BKCa电流;激光共聚焦观察BKCaα亚单位在VSMCs胞膜及胞质内的分布。结果 SHR较WKY大鼠的收缩压与舒张压均有显著升高(P<0.05);全细胞外向钾电流密度及BKCa电流密度均有显著性增加(P<0.05);SHR的BKCaα亚单位在胞膜及胞质内均有广泛分布,SHR大鼠VSMCs胞质与胞膜的荧光强度较WKY大鼠均有显著性升高(P<0.05)。结论 BKCa电流密度增加可能与BKCa通道α亚单位的表达增多有关,SHR大鼠VSMCs的BKCa电流密度增加引起血管的舒张,不能抵消平滑肌细胞的肌源性收缩可能是导致高血压的发生机制之一。更多还原

【Abstract】 Objective To observe the differences in large conductance calcium-activated potassium (BKCa) current and expression of BKCa channel α subunits in vascular smooth muscle cells (VSMCs) isolated from mesenteric arteries between spontaneous hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats. Methods Tail cuff blood pressure of rats was measured in 20 SHRs and 20 WKY rats aged 16-18 weeks. The VSMCs were isolated using collagenase. The total outward potassium current and BKCa current were observed using the whole cell patch clamp. The expression of BKCa α subunits of VSMCs was observed using confocal imaging. Results Both systolic blood pressure and diastolic blood pressure of SHRs increased significantly compared with those of WKY rats (P<0.05). The whole cell outward potassium current density and BKCa current density of VSMCs from SHRs were significantly larger than those of WKY rats (P<0.05). BKCa α subunits were distributed not only uniformly along the plasmalemmas but also extensively in cytoplasmic regions; the average pixel intensity of BKCa α subunit in cytoplasm and plasmalemmas was highly increased in SHRs compared with that in WKY rats (P<0.05). Conclusion The increased BKCa current density of VSMCs from SHRs may be related to the high expression of BKCaα subunits. The VSMCs relaxation caused by increased BKCa current density cannot counteract myogenic tone of artery,which contributes to genesis and development of chronic hypertension.更多还原