“In contrast, several natural and synthetic reducing compounds (i.e., glutathione, dihydrolipoic acid, homocysteine, N-acetyl-L-cysteine , dithiothreitol, and non-thiol cell-impermeable reductant, tris-(2-carboxyethyl)phosphine), but not oxidized glutathione or alpha-lipoic acid effectively up-regulated the release of sTM in endothelial cells.”