雷诺嗪抑制心肌细胞自发性钙漏机制研究

Ranolazine prevents spontaneous Ca^(2+) release in a knock-in mouse model with calsequestrin mutation R33Q

目的:探讨雷诺嗪对心肌细胞钙漏的影响及其机制。方法:分离儿茶酚胺敏感性室速转基因小鼠CASQ2R33Q心室肌细胞,应用钙显像技术探讨雷诺嗪对R33Q细胞内钙转运的影响。结果:91%R33Q细胞在30nmol/L异丙基肾上腺素(Iso)刺激下可诱发自发性钙波;10μmol/L雷诺嗪预处理孵育后,仅40%R33Q细胞可被Iso诱发出自发性钙波(P<0.05)。在Iso诱发自发性钙波后,再灌流雷诺嗪,75%的细胞自发性钙波完全被抑制。雷诺嗪对基础状态下心肌细胞的钙瞬变参数无明显作用,但显著抑制Iso所致钙瞬变幅值增高、延缓Iso所致钙瞬变衰减的加速和降低Iso所致肌浆网钙库的增加。在穿孔的R33Q细胞,雷诺嗪对自发性钙火花参数无明显影响。结论:雷诺嗪可以抑制Iso所致的心肌细胞钙漏,其机制与直接阻滞兰尼丁受体无关,雷诺嗪具有β受体阻滞效应是可能机制之一。

Objective：To assess the effects of ranolazine on the arrhythmogenesis in isolated CASQ2R33 Q myocytes.Method：Ventricular myocytes were isolated from homozygous CASQ2R33 Q mice.Calcium imaging techniques were used.Result：Isoproterenol（Iso,30nM）elicits spontaneous Ca^2＋ transients（SCaTs）in 91%myocytes.Pretreatment with ranolazine（10μmol/L）significantly prevented Iso induced SCaTs（40%,P〈0.05）.Further,we found that Ran can also significantly abolish Iso induced-SCaTs（6out of 8cells）.Ranolazine partly reversed Iso-induced enhancement of Ca^2＋ handling;while ranolazine did not significantly affect them in absence of Iso.In permeablized myocytes,ranolazine did not influence the parameters of Ca^2＋ sparks.Conclusion：Ranolazine effectively prevents spontaneous Ca^2＋ release in isolated CASQ2R33 Q myocytes induced by Iso,while ranolazine does not influence the Ca^2＋ handling in absence of Iso,suggesting that the underlying mechanism is not associated with the direct blockage of the ryanodine receptor,but instead likely associated with the blockage of beta adrenergic receptor.