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.— G orsky , L. D.; F orstermann , U.; I shii , K.; M urad , F. Production of an EDRF‐like activity in the cytosol of N1E‐115 neuroblastoma cells. FASEB J. 4: 1494‐1500; 1990.