代谢抑制处理后大鼠心室肌细胞反向Na^+/Ca^(2+)交换体转运功能的变化

Changes of the reverse mode of Na^+/Ca^(2+) exchanger in isolated rat ventricular myocytes subjected to metabilic inhibition

目的:利用荧光标记法观察代谢抑制处理后,大鼠心肌细胞反向Na+/Ca2+交换体(NCX)转运功能的变化。方法:酶解法分离制备钙耐受心肌细胞用Fura-2/AM负载,采用双激发荧光光电倍增系统(IonOptix Photom etry Sys-tem)检测钙信号。结果:细胞置于无Na+液后,可见[Ca2+]i逐渐升高,L-型Ca2+通道阻断剂n ifed ip ine在浓度为1μmol/L时,不影响此现象;而NCX的抑制剂N i2+,在浓度为1 mmol/L时,则完全阻断[Ca2+]i的升高。采用20mmol/L乳酸加10 mmol/L脱氧葡萄糖作为代谢抑制物处理心肌细胞不同时间,正常Tyrode液灌流10 m in,之后检测无Na+液引发[Ca2+]i升高效应的变化,发现5 m in处理与对照组无显著性差异,10和30 m in处理后此效应逐渐减弱。结论:首次发现,代谢抑制处理后心肌NCX的反向转运功能被抑制,阐明其调节机制,将为心肌缺血/再灌注损伤的治疗提供新思路。

AIM. To study the reverse mode of Na^＋/Ca^2＋ exchanger （NCX） in isolated adult rat ventricular myocytes subjected to metabolic inhibition. METHODS： Single left ventricular myocytes were enzymatically isolated and loaded with Fura-2/AM. Intracellular calcium concentration （ [ Ca^2＋ ]i ） was measured by IonOptix Photometry System. RESULTS： ① [ Ca^2＋ ]i was increased after ventricular myocytes exposed to Na^＋-free solution （NMDG solution） , and returned to baseline following washout. Nifedipine （ 1 μmol/L} , the selective inhibitor of L-type calcium channel, did not affect NMDG solution-induced increases in [ Ca^2＋ ]i, while Ni^2＋ （ 1 mmol/L）, the selective inhibitor of NCX, almost completely blocked the effect. ② In myocyte subjected to 20 mmol/L lactate and 10 mmol/L Deoxy-glucose treatment for 5, 10 and 30 min respectively, followed by 10 min normal Tyrode solution perfusion, NMDG solution induced increases of [ Ca^2＋ ]i was time-dependently inhibited. CONCLUSION： The findings provide evidence that alter metabolic inhibition treatment the reverse mode of NCX in ventricular myocytes is attenuated.