Nitric oxide protects murine embryonic liver cells (BNL CL.2) from cytotoxicity induced by glucose deprivation

We investigated the protective effects of nitric oxide on cell death of mur ine embryonic liver cells (BNL CL.2) after glucose deprivation. Endogenous nitric oxide production by BNL CL.2 cells was induced by 6 hr pretreatment with interferon-gamma and lipopolysaccharide. We used sodium nitroprusside and S-nitroso-L-glutathionc as exogenous nitric oxide-generating compounds. All agents were used at doses that did not show direct cytotoxicity as mea sured by crystal violet staining assay. In the BNL CL.2 cells, the viabilit y dropped very steeply after 24 hr incubation with glucose-free media. Endo genous nitric oxide produced by treatment of the cells with interferon-gamm a and lipopolysaccharide protected the cells from glucose deprivation-induc ed cytotoxicity, but did not protect them in the presence of the nitric oxi de synthesis inhibitor, NG-monomethyl-L-arginine. Exogenous nitric oxide pr otected the cells from glucose deprivation-induced cytotoxicity in a concen tration-dependent manner. Cytoprotection by nitric oxide donors was abolish ed by the use of nitric oxide scarvenger, 2-phenyl-4,4,5,5,-tetramethylimid azole, but not by the soluble guanosine cyclase inhibitor, 1H-[1,2,4]oxadia zole[4,3-a]quinoxalin-1-one. In addition, cytoprotective effects comparable to endogenous or exogenous nitric oxide were not observed when the cells w ere incubated with dibutyl guanosine 3',5'-cyclic monophosphate. Based upon these results, we suggest that nitric oxide may enhance the cell survival of BNL CL.2 cells after glucose deprivation via a guanosine 3',5'-cyclic mo nophosphate-independent pathway.