钙依赖途径在高糖致心肌细胞肥大中的作用

目的探讨体外培养条件下钙调神经磷酸酶(CN)和钙调蛋白激酶Ⅱ(CaMKⅡ)是否参与高糖诱导的心肌细胞的肥大反应。方法新生SD大鼠心肌细胞在含150mL/L的新生牛血清培养48h后,换用无血清培养基培养24h,然后用正常糖(5.5mmol/L的D-葡萄糖)、高糖(25mmol/L的D-葡萄糖)和等渗糖(5.5mmol/L的D-葡萄糖+19.5mmol/L的L-葡萄糖)分别培养48h。检测心肌细胞肥大指标:表面积和蛋白含量;用钙成像技术研究其钙瞬变特点;以及利用CN和CaMKⅡ的阻断剂CsA和KN93验证两种酶在肥大过程中的作用。结果与正常糖组和等渗对照组相比,高糖可以诱导心肌细胞肥大和钙超载,增加了心肌细胞的表面积和蛋白含量。CsA和(或)KN93可明显抑制心肌细胞的肥大。结论 CN和CaMKII在高糖诱导的心肌细胞肥大过程中发挥重要的作用。

Role of Ca2+-dependent pathways in high glucose-induced cardiomyocyte hypertrophy

Objective To examine whether calcineurin(CN) and calcium/calmodulin-dependent kinase Ⅱ(CaMKⅡ) are involved in cardiac hypertrophy reaction induced by high glucose in cultured neonatal cardiomyocytes. Methods Cardiomyocytes isolated from neonatal SD rats were cultured for 48 h in DMEM containing 150 mL/L newborn calf serum,and then stored with serum-free medium for 24 h.The cells were treated with normal glucose,high glucose or osmotic control medium for 48 h,respectively.In high-glucose group,the inhibitors,CsA and KN93,were used to determine the effects of CN and CaMKⅡ on cardiomyocyte hypertrophy.We measured the surface area and total protein content of all the treated cardiac myocytes and determined the pattern of calcium transients. Results The cell surface area and total protein content were increased in high-glucose group,and high glucose induced calcium overload compared with the other two groups.Application of CsA and/or KN93 could significantly inhibit cardiomyocyte hypertrophy. Conclusion CN and CaMKII play a critical role in the development of cardiomyocyte hypertrophy induced by high glucose.