高血压大鼠冠状动脉平滑肌细胞大电导钙激活钾通道的变化

目的研究在高血压背景下大电导钙激活钾(BK)通道的功能改变及其机制。方法用酶解消化方法分离12～16周龄自发性高血压大鼠(SHR)和WKY大鼠冠状动脉平滑肌细胞(CASMCS),采用膜片钳全细胞模式记录SHR和WKY大鼠CASMCSBK电流,SHR和WKY大鼠BKα亚基和β1亚基mRNA水平用实时定量取聚合酶链式反应和凝胶电泳测定,蛋白水平表达用免疫组化的方法测定。结果 SHR大鼠CASMCS(n=6)BK电流密度比WKY(n=7)高2.03±0.62(P0.01);在mRNA水平,BKβ1亚基表达SHR组明显高于WKY组5.534±1.03倍(n=4,P0.05),BKα亚基表达则无明显差异(1.266±0.12,n=4,P0.05);BKβ1亚基和α亚基的表达SHR大鼠高于WKY大鼠。结论 SHR大鼠CASMCSBK电流密度比WKY大鼠增大,在mRNA和蛋白水平上BKβ1亚基表达也比WKY大鼠增强,这种变化可能是机体在高血压时自我调节的结果 。

Changes of coronary arterial smooth muscle cell large conductance Ca2+-activated K+ channel composition and current modulation during hypertension

Objective To study the changes of coronary arterial smooth muscle cells （CASMCS） large conductance Ca^2＋-activated K^ ＋（BK） channel composition and current modulation during hypertension. Methods Twelve-sixteen weeks old spontaneously hypertensive rat（SHR） and wistar kyoto（WKY） rats CASMCS were isolated by an enzyme digestion method. BK currents in individual CASMCSs of SHR and WKY rats were recorded by the patch-clamp technique in a whole-cell configuration at room temperature. The mRNA level of SHR and WKY rats BK α, 131 subanit were compared by means of real-time polymerase chain reaction. The immunohistochemisty were took to show the BK α and 131 subunit protein level. Results The BK current density of SHR CASMCS was 2.03 ± 0.62 folds higher than WKY（n = 7,P 〈 0.01 ）. There exited a significant difference（ n 〈 0.05 ）. In mRNA study, a dramatic increase of 5. 534 ± 1.03 folds in SHR BK 131 subunit was found（n =4,P 〈0.05 ） ;The average amount of α subunits mRNA in SHR seemed also more than WKY group, but there was no significant difference （1. 266 ± 0.12, n = 4 ,P 〉 0. 05 ）. The immunohistochemistry outcome suggested the BK α and 131 subunit protein level both higher expressed in SHR group. Conclusions The average BK channel current density of SHR CASMCS is larger than WKY rats. The expression of BK β1 subunit mRNA and protein in SHR CASMCS are both higher than that of WKY rats which may be an auto-regulation mechanism to buffer vasoconstriction of resistance vessels exposed to high blood pressure. [ Chinese Journal of Cardiac Pacing and Electrophysiology,2010,24 （ 2 ） ： 162 - 166 ]