Background: Newborn infants are highly vulnerable to oxidative stress. Following birth asphyxia, oxidative injury due to ischemia-reperfusion can result in significant brain and heart damage, leading to death or long-term disability.
Study question: The study objective was to evaluate the effectiveness of antioxidant gamma-L-glutamyl-L-cysteine (γGlu-Cys) in inhibiting oxidative injury to cultured embryonic cardiomyocytes (H9c2 cells).
Study design: Control and γGlu-Cys-treated (0.5 mM) H9c2 cells were incubated under 6-hour ischemic conditions followed by 2-hour simulated reperfusion.
Measures and outcomes: To quantify oxidative stress-induced apoptosis sustained by cardiomyocytes, lactate dehydrogenase (LDH) release and the presence of cytosolic cytochrome c were measured, as well as the number of secondary lysosomes visualized under electron microscopy.
Results: Compared to controls, H9c2 cells coincubated with γGlu-Cys during ischemia-reperfusion exhibited a significant reduction in both LDH release into the incubation medium [23.88 ± 4.08 (SE) vs. 9.95 ± 1.86% of total; P = 0.02] and the number of secondary lysosomes [0.070 ± 0.009 (SD) vs. 0.043 ± 0.004 per μm; P = 0.01]. Inhibition of LDH release with γGlu-Cys was the same (P = 0.67) as that of a caspase inhibitor. The significant increase in cytosolic cytochrome c (P = 0.01) after ischemia-reperfusion simulation further supports γGlu-Cys's role in apoptosis prevention.
Conclusions: It is concluded that the glutathione precursor γGlu-Cys protects cultured embryonic cardiomyocytes from apoptosis-associated oxidative injury.