Effects of hypoxia-inducible factor-1 on intracellular calcium transport in fetal rat cardiomyocytes under hypoxia

Zhang Li; Deng Chun-yu; Kuang Su-juan; Zhang Xiao-hua; Zhuang Jian; Zhou Cheng-bin

doi:10.13498/j.cnki.chin.j.ecc.2017.02.12

Abstract：Objective This study aimed to investigate the effects of hypoxia-inducible factor-1 ( HIF-1) on intracellular cal-cium ( Ca2+) transport in fetal rat cardiomyocytes under hypoxia and to explore new methods of myocardial protection. Methods Car-diomyocytes from Sprague-Dawley ( SD) rat aged 14~18 days were isolated and placed in a tri-gas incubator containing 5% CO2 , 3%O2 , and 92% N2 . Cell culture was maintained at 37℃ for 24 h and divided into , control group, the group treated with HIF-1 agonist ( DMOG group) , and the group treated with HIF-1 inhibitor ( Acriflavine group) . Real-time fluorescent quantitative PCR ( RT-PCR) and Western blotting were used 24 hours after treatment to detect the mRNA and protein expression of HIF-1α, L-type Ca2+channels, T-type Ca2+ channels, sodium-calcium exchanger ( NCX) , ryanodine receptors, and Ca2+-ATPase of sarcoplasmic reticulum ( SER-CA2a) . The change of intracellular Ca2+ concentration in cardiomyocytes was monitored by a laser scanning confocal microscope. Results mRNA expression of HIF-1αin the DMOG group was significantly higher and that of Acriflavine group was lower than control group. T-type Ca2+channels mRNA in the DMOG group was higher than Acriflavine group. DMOG group had a increased level of NCX, where as the Acriflavine group showed a significantly reduced level. Acriflavine group had lower expression of ryanodine receptors but higher SERCA2a mRNA expression ( P<0.05, n=5) . Western blotting results showed an enhance dexpression of HIF-1αand L-type Ca2+ channels in DMOG group. ( P<0.05, n=5). The amount of calcium fluorescence in DMOG group was significantly higherthan control and Acriflavine group ( P<0.001, n=10) . Conclusions Under hypoxia, DMOG over activates HIF-1 and can lead to signifi-cant intracellular Ca2+ overload inside cardiomyocytes of fetal rats. Acriflavine is capable of inhibiting the activity of HIF-1 and reduc-ing the intracellular Ca2+ load inside the cardiomyocytes,which may protect immature myocardium.