Effects of sodium nitroprusside on the catecholamine synthetic pathway in the adrenal medulla of rats.

We studied the effect of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on tyrosine hydroxylase (TH) activity and epinephrine and norepinephrine levels in the adrenal medulla of rats. TH activity and the levels of epinephrine and norepinephrine in the adrenal medulla of the SNP+nicotine (Nic)-treated group were increased significantly compared to those in the control, Nic-treated and SNP-treated groups. Furthermore, methylene blue inhibited this increase in TH activity. The data suggest that the NO derived from SNP may increase TH through the guanylyl cyclase pathway in the presence of Nic.