糖尿病冠状动脉平滑肌细胞大电导钙离子激活钾通道开放概率及蛋白表达的变化  

Changes in open probability and protein expression of large conductance Ca^(2+)-activated K^+ channel in coronary smooth muscle cells of diabetic rats

作　　者：吴莹[1] 王如兴[1] 李肖蓉[1] 季圆[1] 郁志明[1] 李库林[1] 郑杰[1] 张常莹[1] 刘晓宇[1] 

机构地区：[1]南京医科大学附属无锡市人民医院心脏中心,江苏南京214023

出　　处：《中国心脏起搏与心电生理杂志》2013年第1期60-62,共3页Chinese Journal of Cardiac Pacing and Electrophysiology

基　　金：国家自然科学基金资助项目(项目编号:81070157);江苏省自然科学基金资助项目(项目编号:BK2011179);江苏省人事厅"六大人才高峰"第七批高层次项目(项目编号:006);江苏省医学重点人才资助项目(项目编号:RC2011034)

摘　　要：目的研究糖尿病对冠状动脉平滑肌细胞大电导钙离子激活钾通道(BK通道)开放概率(NP0)及蛋白表达的影响,探讨糖尿病冠状动脉损伤的分子机制。方法采用链脲霉素腹腔内注射建立糖尿病大鼠动物模型,成功建立20只糖尿病大鼠动物模型作为糖尿病组;对照组(n=20)相应注射生理盐水。酶消化法分离冠状动脉平滑肌细胞,单通道膜片钳实验技术记录大鼠冠状动脉平滑肌细胞BK通道电流;采用Western blot实验方法测定大鼠冠状动脉平滑肌细胞BK通道亚基的蛋白表达。结果在电极外液钙离子浓度为1μmol/L,刺激电位为0,20,40,60,80,100和120 mV条件下,糖尿病组冠状动脉平滑肌细胞BK通道NP0明显低于对照组(P<0.05)。如刺激电位为120 mV时,对照组和糖尿病组大鼠冠状动脉平滑肌细胞BK通道NP0分别为1.210 5±0.048 1(n=5)和0.5217±0.1346(n=5);与对照组比较,糖尿病组BK通道α亚基蛋白表达无差异(P>0.05),但β1亚基蛋白表达下降了63%(P<0.05)。结论糖尿病冠状动脉平滑肌细胞BK通道β1亚基表达下调、BK通道NP0降低可能是糖尿病冠状动脉功能损伤的重要原因。Objective To investigate the changes of open probability （ NP0 ） and protein expression of large conductance Ca2＋-activated K＋ channel （BK channel） in coronary smooth muscle cells of diabetic rats and to elucidate the molecular mechanisms of coronary dysfunctions due to diabetes. Methods Streptozotocin-induced rat diabetic animal model was established successfully by injection intraperitoneally. 90 diabetic rats were obtained in this study including 10 for patch clamp, and 10 for Western blot. Coronary smooth muscle cells were isolated by enzyme digestion. The BK currents in control and diabetic groups were recorded by patch clamp technique in single channel configuration and BK channel protein expression in normal and diabetic group were measured by Western blot. Results Compared with control group, the NPo of BK channels in diabetic group were significantly decreased at calcium 1 μmol/L in external solution and test potentials at 0, 20, 40, 60, 80, 100 and 120 InV. NP0 of BK channels were t. 210 5 ± 0. 048 1 （ n=5 ） in control group and 0. 521 7 ±0. 134 6 （n = 5 ） in diabetic group respectively at 120 mV test potentials. There was no significant difference in a1-subunit protein expression between the groups （P〉0.05）, however, 131-subunit protein expression was remarkably reduced in diabetic group than in control group （ P〈0.05 ）. Conclusion Downregulation of β1-subunit, decrease of the NP0 of BK channels in smooth muscle cells of diabetic coronary arteries may be the important causes for coronary dysfunction.

关 键 词：心血管病学 大电导钙离子激活钾通道 Β1亚基 冠状动脉 糖尿病 

分 类 号：R331.38[医药卫生—人体生理学] R587.1[医药卫生—基础医学]