增强型绿色荧光蛋白转染小鼠心脏后瞬时外向钾电流及钠钙交换电流的变化

目的探讨绿色荧光蛋白(GFP)转染对心脏瞬时外向钾电流(Ito)及钠钙交换电流(INCX)的影响。方法20只雄性小鼠等量随机分为对照组和增强型GFP(EGFP)组。EGFP组小鼠采用8点注射法均匀注射100μl腺病毒于左室游离壁上,对照组注射等量无菌生理盐水。一周后分离单个心室肌细胞,用膜片钳记录Ito及INCX。结果与对照组相比,EGFP组几乎所有测定电压下,Ito电流密度显著减小如+60 mV时为8.40±1.55 pA/pF(n=9)vs 36.77±8.12 pA/pF(n=11),P<0.05]。INCX的前向模式不因转染EGFP变化如-80 mV时为-0.35±0.05 pA/pF(n=8)vs-0.42±0.08 pA/pF(n=10),P>0.05],但反向模式电流显著增大如+80 mV时为1.47±0.10 pA/pF(n=8)vs 0.72±0.05 pA/pF(n=10),P<0.05]。结论 EGFP转染可使心脏Ito显著减小,而INCX仅反向模式电流增大,其综合效应可能导致细胞内钙增加。

Alterations of cardiac transient outward K+ current and Na+/Ca2+ exchanger current in enhanced green fluorescent protein-transfected mouse heart

Objective To explore the changes of transient outward K+ current(Ito) and Na+/Ca2+ exchanger current(INCX) in enhanced green fluorescent protein(EGFP)-transfected mouse heart.Methods Twenty male mice were equally and randomly divided into control group or EGFP group.For EGFP group,adenovirus(100 μl) integrated with EGFP was injected into 8 sites in mouse heart.And for control group,sterile saline(0.9%,100 μl) was used.A week later,the mouse hearts were digested and the single cells were isolated to record Ito and INCX by patch clamp technique.Results In EGFP group,the densityof Ito was significantly lower than that in control group 8.40±1.55 pA/pF(n=9) vs 36.77±8.12 pA/pF(n=11),+60 mV,P<0.05].No change was found in forward mode in INCX in EGFP group -0.35±0.05 pA/pF(n=8) vs-0.42±0.08 pA/pF(n=10),-80mV,P>0.05],but the current density was increased in reverse mode 1.47±0.10 pA/pF(n=8) vs 0.72±0.05 pA/pF(n=10),+80 mV,P<0.05].Conclusion Transfection of EGFP can induce a smaller Ito and a higher reverse mode of INCX.It maybe cause an increased intracellular Ca2+ concentration.