摘要
为研究白细胞介素-2(IL-2)对心肌的负性肌力作用的可能机制,本文采用酶解分离成年大鼠心室肌细胞,用细胞内双波长荧光系统和膜片钳全细胞记录检测细胞膜钙离子通道和细胞内酸碱度(pHi)及钙水平的变化,分别以fura-2/AM和BCECF/AM作为细胞内钙离子和氢离子荧光指示剂。结果:(1)IL-2(2.5-200U/ml)浓度依赖性地降低单个心室肌细胞电刺激诱导的钙瞬变幅度,使舒张末钙水平升高,选择性κ-阿片受体阻断剂nor-BNI(10nmol/L)可阻断IL-2对心肌细胞内钙的作用;(2)用200U/ml的IL-2灌流10min后,与对照组相比膜片钳全细胞记录的L-型钙电流无明显改变;(3)用200U/ml的IL-2灌流后,与对照组相比Mn2+对fura-2/AM的淬灭率无明显改变。(4)IL-2(200U/ml)使大鼠心室肌细胞pHi降低,其作用可被选择性κ-阿片受体阻断剂nor-BNI(10nmol/L)所减弱。结论:IL-2引起的心室肌细胞pHi降低可能是其负性肌力作用机制之一,细胞膜上L-型钙离子通道可能不参与IL-2降低心肌收缩力的作用;细胞膜上的κ-阿片受体可能介导IL-2对心肌的负性肌力作用。
In the present study, we investigated the effect of interleukin-2(IL-2)on the sarcolemmal calcium channel and intracellular pH(pHi)in enzymatically isolated ventricular myocytes with whole cell patch clamp and spectrofluorometry techniques. Fura-2/AM and BCECF/AM were used as the intracellular calcium and hydrogen probe, respectively. It was shown that IL-2(2.5 - 200U/ml)decreased the amplitude of electrically induced[Ca2+ ]i transients of ventricular myocytes in a dose-dependent manner and increased the end-diastolic calcium level. Pretreatment with a specific κ-opioid antagonist nor-BNI(10nmol/L)abolished the effect of IL-2 (200U/ml)on the [Ca2+ ]li transients in cardiomyocytes. Perfusion with IL-2 had no significant effect on whole cell L-type calcium current of cardiomyocytes. We also found that pretreatment with IL-2 did not elicit the significant alteration in the initial rate of Mn2+ quench activated by electrical stimulation. IL-2 decreased the intracellular pH(pHi)of cardiomyocytes, which could be attenuated by nor-BNI. It is concluded that the decrease of pHi induced by IL-2 may be one of the mechanisms of negative inotropic effect of IL-2, in which L-type Ca2+ channel of ventricular myocytes was not involved. The cardiac effect of IL-2 is mainly mediated by cardiac κ-opioid receptors.
出处
《细胞生物学杂志》
CSCD
北大核心
2003年第1期41-47,共7页
Chinese Journal of Cell Biology
基金
浙江省自然科学基金青年人才专项奖金资助(RC99038)
