饱和脂肪酸致乳鼠心肌细胞损伤凋亡的代谢机制

Metabolic mechanism of neonatal rat cardiomyocyte injury and apoptosis induced by saturated fatty acids

目的:观察饱和脂肪酸所致乳鼠心肌细胞损伤凋亡过程中对脂肪酸摄取、利用的改变。方法:应用饱和脂肪酸棕榈酸盐(palmitate,PMT)培养乳鼠心肌细胞,观察心肌细胞损伤、凋亡程度随时间的变化和心肌细胞发生凋亡前脂肪酸转运体(FAT/CD36)的表达、分布及肉碱脂酰基转移酶-1(CPT-1)活性的变化。结果:PMT诱导心肌细胞凋亡呈显著的时间依赖效应。与PMT共孵育4 h后,乳鼠心肌细胞膜中FAT/CD36的含量显著增加,且在时间上早于FAT/CD36 mRNA表达量的升高。在PMT处理早期,M-CPT-1 mRNA的表达量升高,并伴有CPT-1酶活性增强。随着与PMT共孵育时间的延长,心肌细胞膜FAT/CD36蛋白的含量未出现变化,但CPT-1酶的活性逐渐下降,心肌细胞凋亡的数量增加。结论:心肌细胞对长链脂肪酸的摄取没有减少,但氧化利用能力下降,这可能为导致长链脂肪酸及其中间代谢产物在细胞内蓄积,损伤心肌细胞,引起心肌细胞凋亡的机制之一。

AIM： To study the changes of fatty acid uptake and utilization during saturated fatty acidinduced cardiomyoeyte apoptosis in neonatal rats. METHODS： We observed palmitate-inducing cell apoptosis using annexin V-FITC and PI double-stained flow cytometry, change of fatty acid transporter/ CD36 （FAT/CD36） expression and distribution using Western blotting, and activity of carnitine palmityl transferase-1 （CPT-1） using liquid scintillation detecting system. RESULTS： Cardiomyocyte apoptosis rate was increased significantly after 16 h treatment of palmitate. FAT/CD36 protein content on membrane increased significantly after 4 h treatment, whereas its mRNA increased significantly after 8 h treatment. Following the time of treatment by prolonged palmitate, there was no significant change of FAT/CD36 protein content on the membrane, but there was a significant decline of CPT-1 activity and increase of cardiomyocyte apoptosis. CONCLUSION： Accumulation of long-chain fatty acids and its intermediate metabolite in cardiomyocytes due to the decline of oxidation activity may be one of the mechanisms for palmitate-induced cardiomyocyte injury and apoptosis.