论文部分内容阅读
目的 观察钙调蛋白激酶Ⅱ(CaMKⅡ)抑制剂KN-93对肥厚心肌细胞L型钙电流(ICa,L)及细胞内钙离子浓度([Ca2+]i)的影响.方法 选取雌性新西兰大白兔48只,随机(随机数字法)分为4组:假手术组(sham组)、心肌肥厚组(LVH组)、心肌肥厚+KN-93组(KN-93组)、心肌肥厚+KN-92组(KN-92组),每组12只,通过缩窄腹主动脉制备兔心肌肥厚模型,Sham组仅游离腹主动脉未进行缩窄.8周后,采用胶原酶消化法分离单个心肌细胞,应用穿孔膜片钳技术记录L型钙电流(ICa,L)；应用钙荧光指示剂Fura-2/AM结合图像分析技术测定各组心肌细胞内[Ca2+]i.结果 8周后,心肌肥厚模型建立成功.在0 mV时LVH组、Sham组的峰值ICa.L分另为(1.38±0.3)nA、(0.87±0.1)nA(P＜0.01,n=12),电流密度分别为(6.7±1.0)pA/pF、(6.3 ±0.7)pA/pF(P＞0.05,n=12).当KN-92及KN-93在浓度为0.5μmol/L时,可分别使肥厚心肌细胞0 mV时的峰值ICa,L降低(9.4±2.8)％、(10.5±3)％(P＞0.05,n=12)；当浓度增至1 μmol/L时,其峰值ICa,L降低程度分别为(13.4±3.7)％、(40±4.9)％(P＜0.01,n=12).Sham组、LVH组、KN-92组及KN-93组中心肌细胞[Ca2+]i分别为(98.0±12.3)nmol/L、(154.0±26.2)nmol/L、(147.0±29.6)nmol/L和(108.0±21.2)nmol/L.结论 CaMKⅡ特异性抑制剂KN-93可有效抑制肥厚心肌细胞ICa.L,减轻细胞内钙超载,这可能是其抗肥厚心肌室性心律失常发生的主要细胞电生理机制.“,”Objective To investigate the effect of the calmodulin kinase Ⅱ Inhibitor KN-93 on L-typecalcium current(ICa,L)and intracellular calcium concentration([Ca2+]i)in hypertrophic cardiac myocytes.Methods Forty-eight female New Zealand white rabbits were randomized(random number)into four groups(12 animals in each group):the sham operation group(sham group),the left ventricular hypertrophy group(LVH group),the myocardial hypertrophy + KN-93 group(KN-93 group),and the myocardial hypertrophy + KN-92 group(KN-92 group).Myocardial hypertrophy in the rabbits was established by coarctation of the abdominal aorta.In the sham group,the abdominal aorta was dissociated without coarctation.Eight weeks after coarctation,single ventricular myocytes were isolated by enzymaticdissociation,and ICa,L was recorded using perforated-patch recording(PPR)techniques.[Ca2+]i was measured using single-cell calcium imaging with the fluorescence calcium indicator dye fura-2/AM.Results Cardiac hypertrophy was successfully established after 8 weeks of coarctation of the abdominal aorta.The peak ICa,L in the LVH group and the sham group was(1.38 ± 0.3)nA and(0.87 ± 0.1)nA at 0 mV,respectively(P ＜0.01,n =12).There was no significant difference in Ica,L density between the LVH group and the sham group[(6.7 ±1.0)pA/pF vs.(6.3±0.7)pA/pF; P≥0.05,n=12].The addition of either KN-92(0.5 μmol/L)or KN-93(0.5 μmol/L)to the perfusing solution caused a modest steady-state inhibition of peak ICaL(9.4％ ±2.8％,KN-92; 10.5％ ±3％,KN-93)(P≥0.05,n =12)at 0 mV.However,at a higher concentration(1 μmol/L),KN-93 more potently inhibited peak ICa,L(40％±4.9％)compared to KN-92(13.4％ ± 3.7％ ; P ＜ 0.01,n =12).Resting[Ca2+]i levels in fura-2-loaded myocytes isolated from the sham,LVH,KN-92,and KN-93 groups were(98 ± 12.3)nmol/L,(154 ± 26.2)nmol/L,(147 ± 29.6)nmol/L,and(108 ± 21.2)nmol/L,respectively.Conclusions The CaMK Ⅱ specific inhibitor,KN-93,can effectively block ICa,L and reduce intracellular calcium overload in hypertrophic cardiac myocytes.This action may account for the antiarrhythmic effect of KN-93 in hypertrophic ventricular myocardium.