The impact of vasoactive peptides on nitric oxide production in cultured sympathetic neurons

The concentration of nitric oxide was found to be decreased in a hypersympa thetic condition. We carried out experiments on cultured sympathetic neuron s from 12-14-days-old chick embryos to investigate the role of vasoactive p eptides and amine on nitric oxide production. Stimulation of cultured neuro ns with endotllelin-1, norepinephrine and angiotensin-II initially increase s nitric oxide production and subsequently decreases it in a dose-dependent manner (P < 0.05, n = 7). Stimulation of Fura-2 acetoxymethyl ester-loaded neurons with endothelin-l, norepinephrine and angiotensin-II increases the calcium influx (within 30-90 s) and it is then restored to the initial lev el (P < 0.05, n = 7). An additional observation was that specific stimulato r L-arginine significantly increases the nitric oxide release and calcium i nflux into the cells, whereas N-w-nitro-L-arginine methyl ester blunts nitr ic oxide release dose dependently (P < 0.05, n = 7) and does not change the calcium concentration in the cells. We propose that vasoactive peptides and amines inhibit nitric oxide product ion in the cultured sympathetic neuron by regulation of intracellular calci um concentration. (C) 1999 IBRO. Published by Elsevier Science Ltd.