白介素—2对心肌细胞[Ca^2＋]i的作用及其信号转导途径

为研究白介素－2（interleukin-2,IL-2）对心肌细胞内钙浓度（Ca^2 ]i）的影响及其信号转导途径,实验采用酶解法分离成年大鼠心室肌细胞,以Fura-2/AM为钙探针,用细胞内双波长钙荧光系统检测细胞Ca^2 ]i的变化。结果发现：（1）IL－2（0.5-200U/ml）浓度依赖性地降低单个心室肌细胞内钙态,IL－2（200U／ml）对咖啡因诱导的肌浆网内储钙的释放无影响;（2）纳洛酮(naloxone,Nal)(10^-8mol/L）和nor-binaltorphimine(nor-BNI,10^-8mol/L）可阻断IL－2对心肌细胞钙瞬态的作用,而纳曲吲哚（naltrindole,NTI）（10^-6mol/L）不能阻断此作用;（3）κ阿片受体激动剂U50488H（10^-6mol/L）降低心肌细胞钙瞬态,nor-BNI(10^-8mol/L）可阻断此作用;（4）5mg/L百日咳毒素（PTX）预处理可取消IL－2降低心肌细胞钙瞬态的作用,而酪氨酸激酶抑制剂genistein(10^-4mol/L）不能取消IL－2的作用;（5）U73122预处理可阻断IL－2的作用。研究结果表明,IL－2降低心肌细胞钙瞬态的作用,是通过心肌细胞上κ阿片受体介导的,其下游途径包括PTX敏感的G蛋白和磷脂酶C。

Effect of interleukin-2 on intracellular calcium transients in rat ventricular myocytes

In the present study, we investigated the effect of interleukin-2 (IL-2) on the intracellular calcium in enzymatically isolated ventricular myocytes with the use of the spectrofluorometric techniques. It was shown that IL-2 (2.5 200 U/ml) depressed electrically induced Ca(2+) (i) transients of ventricular myocytes in a dose dependent manner. IL-2 (200 U/ml) did not alter the caffeine releasable pool of Ca(2+). Pretreatment with the non selective opioid antagonist naloxone (10(-8)mol/L) or a specific kappa opioid antagonist nor binaltorphimine (nor-BNI, 10(-8) mol/L) abolished the inhibitory effect of IL-2 (200 U/ml) on the Ca(2+) (i) transients of cardiomyocytes, whereas the specific delta opioid antagonist naltrindole (10(-6) mol/L) did not abolish the inhibitory effect. The effect of IL-2 (200 U/ml) was also abolished after pretreatment with pertussis toxin (PTX, 5 mg/L) as well as phospholipase C (PLC) inhibitor U73122 (5 10(-6) mol/L), but not by tyrosine kinase inhibitor genistein (10(-4) mol/L). It is concluded that the depressant effect of IL-2 on the Ca(2+) (i) transients of isolated ventricular myocytes is mainly mediated by cardiac kappa opioid receptor pathway including a PTX sensitive Gi-protein and PLC, but not by tyrosine kinase.