Effects of metabolic inhibition on conduction, Ca transients, and arrhythmia vulnerability in embryonic mouse hearts
Effects of metabolic inhibition on conduction, Ca transients, and arrhythmia vulnerability in embryonic mouse hearts
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DOI：
10.1152/ajpheart.00359.2007
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发表时间：
2007-10-01
影响因子：
4.8
通讯作者：
Weiss, James N.
中科院分区：
文献类型：
--
作者：
Chen, Fuhua;De Diego, Carlos;Weiss, James N.
发育中的心肌比成人心肌更依赖糖酵解，但选择性抑制糖酵解与氧化磷酸化对胚胎心功能的影响尚未得到很好的表征。因此，我们研究了选择性代谢抑制如何影响胚胎小鼠心脏的膜电压和细胞内Ca （Ca-i）瞬态，包括它们对心律失常的易感性。将136只离体小鼠胚胎心脏分别暴露于1)2-脱氧葡萄糖（2DG; 10 mM）或碘乙酸（IAA; 0.1 mM）中，用10 mM丙酮酸代替葡萄糖，选择性抑制糖酵解；或2)线粒体解耦剂质子团羰基氰化物对（三氟甲氧基）苯腙（FCCP; 500 nM）中，用10 mM葡萄糖选择性抑制氧化磷酸化。通过共聚焦成像，我们发现用四甲基罗丹明甲酯（200 nM）监测的线粒体膜电位在2DG或IAA下保持稳定，但在暴露于FCCP后5分钟内去极化。IAA和FCCP降低了心率，抑制了Ca-i瞬态振幅，缩短了80%复极时的动作电位持续时间（APD(80)），并延长了房室传导时间。2DG虽能降低心率和Ca-i瞬态振幅，但对APD（80）和房室传导时间无显著影响。此外，暴露于IAA（28/53）或FCCP（49/83）后，136个胚胎心脏中有77个（57%）发生自发性心律失常。IAA与FCCP致心律失常的类型及发生率无显著差异。这些数据支持糖酵解和氧化磷酸化在调节胚胎小鼠心脏功能中发挥关键代谢作用的观点。
Developing myocardium is more dependent on glycolysis than adult myocardium, yet the effects of selectively inhibiting glycolysis versus oxidative phosphorylation on embryonic heart function have not been well characterized. Accordingly, we investigated how selective metabolic inhibition affects membrane voltage and intracellular Ca (Ca-i) transients in embryonic mouse hearts, including their susceptibility to arrhythmias. A total of 136 isolated embryonic mouse hearts were exposed to either 1) 2-deoxyglucose ( 2DG; 10 mM) or iodoacetate ( IAA; 0.1 mM) with 10 mM pyruvate in place of glucose to selectively inhibit glycolysis or 2) the mitochondrial uncoupler protonophore carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP; 500 nM) with 10 mM glucose present to selectively inhibit oxidative phosphorylation. Using confocal imaging, we found that mitochondrial membrane potential monitored with tetramethylrhodamine methyl ester (200 nM) remained stable with 2DG or IAA but depolarized within 5 min after exposure to FCCP. IAA and FCCP decreased heart rate, inhibited Ca-i transient amplitude, shortened action potential duration at 80% repolarization (APD(80)), and prolonged atrioventricular conduction time to similar extents. Although 2DG decreased heart rate and Ca-i transient amplitude, it did not significantly affect APD(80) and AV conduction time. In addition, spontaneous arrhythmias occurred in 77 of 136 embryonic hearts (57%) after exposure to IAA (28/53) or FCCP (49/83). There were no significant differences in the types or incidence of arrhythmias induced by IAA and FCCP. These data support the idea that both glycolysis and oxidative phosphorylation play critical metabolic roles in regulating cardiac function in the embryonic mouse heart.