Peptide toxin targeting sodium channels in the model of ischemia-reperfusion cell death

Myocardial infarction is one of the most common cardiovascular diseases worldwide. Interruption of coronary blood flow subjects cardiomyocytes to stress, while reperfusion reintroduces substrate and oxygen, providing a sharp normalization of the intracellular milieu. All this paradoxically increases cell death, resulting in ischemia-reperfusion injury. It has long been known that sodium overload in the myocardium is one of the most important mechanisms underlying the ischemia-reperfusion injury. In our work, we used mu-agatoxin-Aa1a to reduce the influx of Na+ at the reperfusion stage and, thereby, to reduce damage. Objective. The aim of the study is to examine the effect of mu-agatoxin-Aa1a on cardiomyocyte cell death in an in vitro ischemia-reperfusion injury model. Materials and Methods. The study was performed on H9C2 cardiomyocyte culture. Fluorescence microscopy was used to assess the apoptosis and necrosis levels, and sodium ion concentration. Spectrophotometric method for determining lactate dehydrogenase concentration was used to confirm the necrosis level. The ischemia-reperfusion injury model was based on 18-hour culture incubation in the medium with partial glucose, serum, and oxygen deprivation, followed by transfer to a nutrient medium for 2 hours. The toxin was added at the beginning of the reperfusion stage Results: In case of increased cell death caused by apoptosis and necrosis in the ischemia-reperfusion injury model, the addition of toxin at a concentration of 50 nM causes an increase in cell survival due to a decrease in the sodium ion concentration. Conclusion. The peptide toxin mu-agatoxin-Aa1a, which targets sodium voltage-gated channels and can change their conductance, at a concentration of 50 nM significantly reduces cardiomyocyte death in an in vitro model of ischemia-reperfusion injury.