| Abstract [eng] |
Every year, 9.14 million people worldwide die from ischemic heart disease. During the course of the disease, oxygen and nutrient supply are compromised due to reduced or complete loss of blood flow in the coronary arteries of the heart. When ischemic processes are prolonged, blood flow is restored surgically, and reperfusion takes place. The sudden restoration of O2 in cardiomyocytes leads to oxidative stress and inflammation and irreversible damaging changes in the myocardium. To study this process under laboratory conditions, the hypoxia-reoxygenation model can be used, where the experimental conditions can be tightly controlled. The present study evaluated the effects of hypoxia-reoxygenation and the mitochondrial antioxidant MitoTEMPO on HL-1 cardiomyocyte viability, calcium content and gene expression. Hypoxia - reoxygenation conditions with 1% and 0.1% oxygen concentrations were investigated to find the most detrimental effects on HL-1 cardiomyocytes. The protective effect of the mitochondrial antioxidant MitoTEMPO on LDH activity, early apoptosis, calcium levels and the expression of genes related to hypoxia (Hif1a) or calcium homeostasis (Cacna1c, Atp2a2, Scl8a1, Ryr2) was investigated. The most appropriate model for hypoxia-reoxygenation studies was found to be using acute 0.1% hypoxia and the nutrient-dense serum-free RPMI 1640 medium. Under these conditions, the greatest difference between hypoxic and normoxic conditions was observed in terms of LDH activity and apoptotic cell counts, which facilitated the assessment of the effects of additional nutrients in further studies. The effect of the mitochondria-targeted antioxidant MitoTEMPO was equivocal. MitoTEMPO reduced LDH levels and the number of apoptotic cells, but it was observed that, under some conditions, higher concentrations could be toxic and cause cell death. Cytoplasmic calcium levels were observed to be higher in hypoxia - reoxygenation conditions, but the antioxidant treatmentresulted in a greater increase in normoxia. There were no marked differences in mitochondrial calcium. The effect of MitoTEMPO was only evident for the Canca1c and Ryr2 genes, where increasing concentrations of the antioxidant reduced their expression under hypoxia. |
