INDUCTION OF CALCIUM-INDEPENDENT NITRIC-OXIDE SYNTHASE ACTIVITY IN CULTURED CEREBELLAR GRANULE NEURONS

Cultured cerebellar granule neurons were assayed for nitric oxide synt hase (NOS) activity by measuring the conversion of L-arginine to L-cit rulline. Granule neurons expressed constitutive NOS activity which was calcium-dependent, Treatment of neuron cultures for 24 h with the com bined stimulation of INF-gamma plus IL-1 beta, TNF-alpha and LPS induc ed NOS activity by 87-fold which was calcium-independent. We conclude that cultured cerebellar granule neurons can express both the constitu tive and inducible forms of NOS activity.