三氧化二砷对豚鼠心室肌细胞内游离钙离子浓度的影响

 目的 研究三氧化二砷(As₂O₃)对豚鼠心室肌细胞内游离钙离子浓度的影响。方法Fluo-3／AM荧光探针标记豚鼠心室肌细胞游离钙离子,激光共聚焦显微镜实时测定不同浓度As₂O₃干预5 min后心室肌细胞的胞浆钙的变化。不同剂量的As₂O₃对正常台氏液中的豚鼠心肌细胞体外浓度递减性干预13 h后心肌细胞DNA片断化的情况。结果 不同浓度As₂O₃对心室肌细胞的胞浆钙影响不同。在正常台氏液中,低浓度As₂O₃引起一过性钙增高,高浓度的As₂O₃引起持续钙增高,并被钙通道阻滞剂维拉帕米不完全阻断。在无钙台氏液中,低浓度As₂O₃对胞浆钙无影响,高浓度的As₂O₃引起持续钙增高。10μmol·L^-1的As₂O₃体外浓度递减性干预13 h后,豚鼠心肌细胞发生DNA的片断化。低于10μmol·L^-1的As₂O₃体外浓度递减性干预13 h后,心肌细胞无明显的DNA片断化。结论 As₂O₃影响细胞外钙内流和细胞内钙库释放,导致心肌细胞内的游离钙升高,其机制可能有电压依赖性钙通道参与。低浓度引起胞内一过性钙升高;高浓度导致胞内持续性钙升高。后者可能是As₂O₃诱导细胞凋亡的机制之一。

Effects of arsenic trioxide on cytosolic calcium concentration in ventriclar my-ocardium of guinea pig

OBJECTIVE To study the effects of arsenic trioxide (As₂O₃) on cytosolic calcium concentration (Ca²⁺]_i) in ventriclar myocardium of guinea pig.METHODS Ca²⁺ in guinea pig's ventriclar myocardium was tagged with Fluo-3/AM fluorescent probe, Ca²⁺]_i was determined by laser confocal microscopy before and after intervention by As₂O₃. The DNA ladders of ventriclar myocardium in normal Tyrode' s solution were evaluated after intervention by As₂O₃ in vitro. RESULTS As₂O₃ at different dosages had different effects on Ca²⁺]_i in guinea pig's ventriclar myocardium. In normal Tyrode's solution, low-dose of As₂O₃ increased the Ca²⁺]_i temporarily, while high-dose of As₂O₃ increased the Ca²⁺]_i continuously, which could be blocked by calcium channel blocker(verapamil)incompletely. In calcium-free Tyrode's solution, low-dose of As₂O₃ had no effects on the Ca²⁺]_i, however, high-dose of As₂O₃ increased the Ca²⁺]_i continuously.DNA gragmentation appeared when rnyocardial cells were continuously interfered by As₂O₃ of a series of concentrations for 13 hours in vitro. The initial arsenic concentration was 10 μmol·L^-1 and then decreased one time every 3 hours. No gragmentation of DNA appeared when the myocardial cells were interfered with As₂O₃ of initial arsenic concentration under 10 μmol·L^-1. CONCLUSION Arsenic can increase cytosolic Ca²⁺]_i by accelerating extra-cellular calcium inflow and releasing intracellular binding calcium. The mechanism might be related to the voltagl-gated calcium channel. The phenomenon that high-dose of As₂O₃ increased the Ca²⁺]_i continuously may be one of the mechanisms that As₂O₃ induced cellular apoptosis.