CONSTITUTIVE TYPE NITRIC-OXIDE SYNTHASE IN CULTURED ASTROCYTES ISOLATED FROM RAT CEREBRA

To define whether astrocytes express a constitutive nitric oxide synth ase (NOS), nitric oxide (NO) producing activity in astrocytes derived fetal rat cerebra was examined. We found that the addition of an NOS i nhibitor to cultures caused decrease in the basal cGMP levels in unsti mulated astrocytes and the decrease was dose-dependent. Further, the e xpression of cNOS activity in unstimulated astrocytes was confirmed by histochemical staining for NADPH diaphorase and by measuring conversi on of L-arginine to L-citrulline. We conclude that cultured astrocytes -express constitutive NOS, in addition to inducible one.