白细胞介素-2对大鼠心肌收缩功能的影响涉及一氧化氮机制

INVOLVEMENT OF NITRIC OXIDE IN THE EFFECT OF INTERLEUKIN-2 ON THE CONTRACTILITY OF RAT VENTRICULAR CARDIOMYOCYTES

为深入研究细胞因子白细胞介素-2(interleukin-2,IL-2)对心肌收缩功能的影响及其可能机制,本实验采用酶解分离成年大鼠心室肌细胞模型,用视频跟踪计算机系统记录测定单个心室肌细胞收缩反应并用双波长荧光系统检测细胞[Ca^(2+)]_i。心肌细胞收缩参数包括最大收缩幅度(dL)、细胞最大收缩速度(+dL/dtmax)、细胞最大舒张速度(-dI/dtmax)和舒张末期细胞长度。结果显示,IL-2(2-1000U/ml)浓度依赖性地抑制心肌细胞dL、±dL/dtmax和舒张末期细胞长度;用一氧化氮(ni-tric oxide,NO)合酶抑制剂L-NAME(100mmol/L)和可溶性鸟苷酸环化酶(sGC)抑制剂ODQ(10mmol/L)可减弱IL-2对心肌细胞收缩的抑制作用,iNOS抑制剂Aminoguanidine(100mmol/L)对IL-2的作用则无明显影响。200U/ml的IL-2可降低单个心室肌细胞电刺激诱导的钙瞬变幅度;ODQ(10mmol/L)可明显抑制IL-2对心肌细胞钙瞬变的作用。以上结果提示IL-2对大鼠心肌细胞收缩功能具有直接抑制作用,其机制可能通过刺激NOS活性,增加NO的生成,激活可溶性鸟苷酸环化酶(sGC)从而导致细胞内Ca^(2+)含量降低所致。

The aim of the present study was to investigate the effect of interleukin-2(IL-2) on the contractility in cardiomyocytes and the underlying mechanisms.Ventrieular myocytes were isolated from adult male Sprague-Dawley rats.Contractile responses were evaluated by use of the video tracking system.Contractile parameters in cardiomyocytes electrically stimulated at 0.2Hz in- eluded peak velocity of cell shortening(+dL/dtmax),peak velocity of cell relengthening (-dL/dt- max),contractile amplitude(dL),and end-diastolic cell length.Calcium transients of ventricular myocytes were determined by the spectrofluorometrie techniques.Dose-dependent inhibition in+ dL/dtmax,-dL/dtmax,dL and end-diastolic cell length were induced by IL-2 at 2-1000 U/ml. Pretreatment with the nitric oxide synthase inhibitor N^W-nitro-L-arginine methyl ester(L-NAME, 100μmol/L)and soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo [4,3a]quinoxalin-1-one (ODQ,10μmol/L) attenuated IL-2-induced inhibition of contractility.Aminognanidine,an in- hibitor of inducible nitric oxide synthase,had no effect on the inhibition by IL-2.IL-2 at 200U/ ml decreased the amplitude of electrically induced [Ca^(2+)] transients of ventricular myocytes.Pre- treatment with ODQ diminished IL-2-induced inhibition of amplitude of the calcium transient.In conclusion,the present study indicates a direct action of IL-2 on cardiomyocyte contraction,possi- bly through an increased NO production,activation of soluble guanylyl cyclase and inhibition in intracellular Ca^(2+) level.