Modulation of the spontaneous activity of rat medial vestibular nuclear neurons by nitric oxide was investigated using the whole-cell patch-clamp technique. The spike frequency was increased by sodium nitroprusside (SNP), a nitric oxide liberating agent, and it was also increased by another nitric oxide liberating agent, sodium-nitroso-N-acetylpenicillamine. L-Arginine, the substrate of nitric oxide synthase, increased the firing of the neurons. The increased SNP-induced firing was inhibited by 1H-[1,2,4]oxadiazolo[4,3-α]quinozalin-1-one (ODQ), a specific inhibitor of guanylate cyclase. These results suggest that nitric oxide increases the neuronal excitability of the neurons by a cGMP-dependent mechanism. Keywords:: nitric oxide, medial vestibular nucleus, action potential
