Nitric oxide protects endothelial cells from tumor necrosis factor-alpha-mediated cytotoxicity: possible involvement of cyclic GMP.

In cultured endothelial cells, incubation with TNF-alpha (50 ng/ml) for 48 h markedly reduced viability of endothelial cells. A 6 h preincubation with Sper/NO (0.03--1 microM) protected endothelial cells in a concentration-dependent manner and increased viability by 63% of control. The NO scavenger PTIO (30 microM) completely abolished cytoprotection by Sper/NO. A cytoprotective effect comparable to Sper/NO was observed when preincubating the cells with 8-bromo cyclic GMP (1-10 microM). Moreover, no protection by Sper/NO occurred in the presence of ODQ (0.1 microM), a selective inhibitor of soluble guanylyl cyclase. Our results demonstrate that NO produces a long-term endothelial protection against cellular injury by TNF-alpha, presumably via a cyclic GMP-dependent pathway.