5-羟色胺对心肌细胞内游离钙浓度的影响

目的　观察 5 -羟色胺 (5 - HT)对新生大鼠心肌细胞内游离 Ca2 + 浓度的影响 ,并探讨其作用机制 .方法　培养 SD大鼠 (1～ 3d)心肌细胞 ,应用特异性 Ca2 +荧光指示剂 Fluo- 3/AM负载细胞 ,激光共聚焦显微镜检测游离 Ca2 + 浓度 .结果　 5 - HT在 10 - 6 ,10 - 5,10 - 4 m ol· L- 1 时均可升高心肌游离Ca2 + 浓度 ,且随剂量增加而加强 ;二氢吡啶类钙通道阻断剂lacidipine可部分拮抗 5 - HT的作用 ;心肌肌浆网内钙释放通道 ryanodine受体调节剂 ryanodine,在 10 - 5mol· L- 1 时也可部分拮抗 5 - HT的作用 ;用 EGTA络合细胞外液中游离Ca2 + ,5 - HT升高心肌游离 Ca2 + 作用明显减弱 ;此外 ,5 - HT二型受体 (5 - HT2 R)阻断剂赛庚定具有显著抑制 5 - HT升高心肌游离 Ca2 + 的作用 .结论　 5 - HT具有升高心肌游离 Ca2 + 的作用 ,其机制可能与细胞外 Ca2 +经 5 - HT2 R或二氢吡啶类钙通道进入细胞以及肌浆网内钙释放有关

Effects of 5-hydroxytryptamine on intracellular freeCa2+ of myocardium

AIM To observe the effects of 5-hydroxytryptam ine (5-HT) on intracellular free Ca 2+ of neonatal rat myocardium and to i nvestigate its mechanism. METHODS Neonatal rat myocardium was c ultured to measure intracellular free Ca 2+ concentration by calcium fluore scent probe Fluo-3/AM and laser confocal microscope. RESULTS 5 -HT was found to increase intracellular free Ca 2+ concentration in a dose-dependent manner. The addition of lacidipine, a dihydr opyridine calcium antagonist, to the cells could partly abolish the 5-HT-induc ed response. Similarly the addition of ryanodine, an regulator of sarcoplasmic r eticulum ryanodine receptor, showed the same action on 5-HT-induced response. When extracellular free Ca 2+ was chelated by EGTA, the increase of free Ca 2+ stimulated by 5-HT was curtailed significantly. Moreover, cyprohatidin e, a 5-HT 2R antagonist, could also partly diminish the 5-HT-induced respons e. CONCLUSION 5-HT increases intracellular free Ca 2+ co ntents, which may be due to extracellular Ca 2+ influx via dihydropyrid ine calcium channels or 5-HT 2R coupled channels as well as the release of Ca 2+ from intracellular stores.