糖尿病大鼠冠状动脉平滑肌细胞中大电导钙离子激活钾通道电流和钙离子浓度变化

摘要

目的 探讨糖尿病大鼠冠状动脉平滑肌细胞中大电导钙离子激活钾通道(BK通道)电流及钙离子浓度的变化.方法 40只SD大鼠随机均分为正常对照组(A组)和糖尿病组(B组).采用链脲霉素腹腔内注射建立糖尿病大鼠模型,酶消化法分离冠状动脉平滑肌细胞,全细胞膜片钳实验和荧光测定方法分别检测冠状动脉平滑肌细胞BK通道电流和钙离子浓度.结果 与A组相比,当刺激电压大于60 mV时,B组冠状动脉平滑肌细胞BK通道电流密度明显下降(P＜0.05);A组冠状动脉平滑肌细胞内钙离子浓度明显低于B组[(103±23) nmol/L vs.(193±22) nmol/L](P＜0.05).结论 冠状动脉平滑肌细胞中BK通道电流下降及细胞内钙离子浓度升高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 large conductance Ca2+-activated K+ channel(BK channel) current and cytosolic calcium concentrations in the coronary artery smooth muscle cells of rats with diabetes. Methods Forty SD rats were equally randomized into two groups of A(normal controls) and B (diabetic rats). The streptozotocin-induced diabetic rat model was successfully established by intraperitoneal injection,and the coronary artery smooth muscle cells were isolated by enzyme digestion. BK channel currents and calcium concentrations were detected by wholecell patch clamp technique and fluorescence assay, respectively. Results Compared with group A, the current density of BK channel in the coronary artery smooth muscle cells was significantly decreased in group B when test potential was more than 60 mV(P<0. 05). The calcium concentration in group A was lower than that in group B [(103±23) nmol/L vs. (193±22) nmol/L](P<0. 05). Conclusion The decrease of BK channel current and increase of cytosolic calcium concentration in the coronary artery smooth muscle cells of rats with diabetes may be the important causes for coronary dysfunction.