PRODUCTION OF AN EDRF-LIKE ACTIVITY IN THE CYTOSOL OF N1E-115 NEUROBLASTOMA-CELLS

Accumulation of cyclic GMP in cultured rat lung fibroblasts was used to test the hypothesis that N1E-115 neuroblastoma cells produce an endothelium-derived relaxing factor (EDRF)-like activity. By using this assay, the production of an EDRF-like activity in homogenates and cytosolic fractions of N1E-115 neuroblastoma cells was observed. Detection of the activity required the presence of superoxide dismutase and was inhibited by hemoglobin. Production of the EDRF-like factor was dependent on L-arginine and NADPH. The apparent K(m) for L-arginine was 1.25 μM and the apparent K(m) for NADPH was 1.67 μM. The production of the EDRF-like activity was inhibited by the L-arginine analogs, N(G)-monomethyl-L-arginine and N(G)-nitro-L-arginine, with apparent K(i) values of 1.0 and 0.3 μM, respectively.