Purpose: Sodium thiosulfate (STS) has of late been proven efficacious in models of urolithiasis and vascular calcification. However, its cardiovascular effects on ischemia reperfusion injury (IR) have not been revealed. Being an antioxidant and calcium chelator, it is assumed to play a vital role in IR as ROS production and calcium overload are major perpetrators of IR injury.
Methods: The cardioprotective effect of STS was evaluated in vitro using H9C2 cardiomyocytes and in vivo using both isolated rat heart and intact left anterior descending artery (LAD) occlusion models of ischemia reperfusion injury. Finally, in silico tools were utilized to establish its possible mode of action. Myocardial injury markers and expression of apoptotic proteins were studied along with myocardial histopathology.
Results: STS of 1 mM recovered H9C2 cells from glucose oxidase/catalase-induced apoptosis. The isolated rat heart treated with STS prior to IR injury improved its hemodynamics and reduced the infarct size to 9%. This was supported by the absence of derangement of cardiac fibers from H&E stained section of LAD-occluded rats. Plasma troponin levels decreased by 15% compared to IR and the myocardium showed diminished apoptotic proteins. An in silico docking analysis revealed higher binding affinity of STS for caspase-3 with a binding energy of - 60.523 kcal/mol for the complex.
Conclusion: The effectiveness of STS as a cardioprotective agent is attributed to the reduction of apoptosis by binding to the active site of caspase-3 in silico, which was substantiated by the reduced expression of caspase-3 and poly ADP ribose polymerase levels.
Keywords: Antioxidant; Caspase-3; In silico; Ischemia reperfusion injury; Langendorff heart; Sodium thiosulfate.