Endogenous glutathione protects against the vascular failure in response to peroxynitrite and endotoxic shock

Part of the nitric oxide (NO) related vascular failure (endothelial dysfunction and vascular hyporeactivity) in various forms of circulatory shock is mediated by peroxynitrite, a toxic oxidant species produced from NO and superoxide. Glutathione is an important endogenous antioxidant, which scavenges hydroxyl radical and peroxynitrite. Here we investigated the role of endogenous glutathione in the cytotoxic effects of peroxynitrite in cultured human umbilical vein endothelial cells (HUVEC), rat aortic smooth muscle cells (RASM), and in isolated rat thoracic aortic vascular rings in vitro. Furthermore, we investigated the role of endogenous glutathione in the development of the vascular failure in endotoxic shock, Depletion of glutathione in vitro with L-buthionine-(S,R)-sulfoximide (BSO) enhanced the cytotoxic effect of peroxynitrite (100 μM - 750 μM) in HUVEC and RASM cells. Exposure of thoracic aortic rings to peroxynitrite in vitro caused a vascular hyporeactivity to noradrenaline and reduced the endothelium-dependent relaxant responses to acetylcholine. These effects were more pronounced in rings obtained from animals obtained from rats in which endogenous glutathione pools had been depleted by in vivo BSO treatment. In vivo treatment of the rats with bacterial lipopolysaccharide (LPS, 15 mg/kg for 6h) resulted in vascular hyporeactivity and endothelial dysfunction ex vivo, which was more pronounced in BSO-treated rats. Taken together, our data demonstrate that endogenous glutathione plays important protective roles against the peroxynitrite- and LPS-induced vascular failure in vitro and in vivo.