Author`s Reply:GGT as predictor of coronary collateral development in chronic coronary total occlusion

Gamma-glutamyltransferase (GGT) is important in maintaining adequate concentrations of intracellular glutathione to protect cells against oxidants. GGT expression can be induced by oxidative stress and inflammatory cytokines. Therefore, serum concentrations of GGT can be used as a marker for increased oxidative stress in humans (1). Oxidative stress is one of the important cellular mechanisms for the development of endothelial dysfunction (2).