Abstract
To investigate the impact of different hypoxia reoxygenation (HR) times on autophagy of rat cardiomyocytes (H9C2). Rat cardiomyocytes were randomly divided into normal control group (group A), hypoxia group (group B), 2 h HR group (group C), 12 h HR group (group D), and 24 h HR group (group E). LC3 II/LC3 I was determined via western blotting, and cell viabilities of cardiomyocytes were measured using methyl thiazolyl tetrazolium (MTT) assay. Cell viabilities in HR model groups were significantly lower than those of group A (P<0.05). LC3 II/LC3 I levels in groups B to D were significantly higher than those of group A (P<0.05), and group D showed the highest LC3 II/LC3 I levels. Cell viabilities in groups B to D were significantly lower than those of group A (P<0.05), with group D showing the lowest cell viabilities (P<0.05). Hypoxia can induce autophagy in rat cardiomyocytes, which can be further activated by reoxygenation; most notable after 12 h. Hypoxia-induced cell injury can be aggravated by reoxygenation. The lowest cell viability was observed at 12 h after reoxygenation; however, cell viability can be recovered after 24 h.
Highlights
Autophagy is a process in which bilayer vesicles are generated within the cell
Cells were randomly divided into two groups (n=3) and cultured in Dulbecco’s minimum essential medium (DMEM) based on the following treatments: (1) normal control group was cultured under normal conditions; (2) hypoxia reoxygenation (HR) model group (B group) was cultured for 2 h under normal conditions, followed by 2 h of hypoxic culture
Cardiomyocytes in groups B and A had cell viabilities of 58.97±1.20% and 92.84±1.49%, respectively, demonstrating significantly lower cell viability in the HR model group compared to the normal control group (P
Summary
Autophagy is a process in which bilayer vesicles (autophagosomes) are generated within the cell. Autophagy can be classified into selective or nonselective autophagy according to selectivity towards target substrates[3]. Nonselective autophagy refers to the transportation and degradation of random cytoplasmic organelles by lysosomes. Selective autophagy exhibits specificity towards the target substrates[4] and can be further classified into the following subtypes according to the selectivity of substrate proteins: mitophagy[5], nucleophagy[6], lipophagy[7], ribophagy[8], and xenophagy[9]. We used H9C2 cells to detect the changes in expression of the autophagyrelated protein LC3 under different hypoxia reoxygenation (HR) periods and to observe the impact of autophagy-induced changes on the cell viability of cardiomyocytes. We further explored changes in autophagy after exposure to hypoxia to elucidate mechanisms with the goal of achieving fine autophagy control
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