Korean J Physiol Pharmacol.  2003 Apr;7(2):73-78.

Roles of Nitric Oxide in Vestibular Compensation

• Jeong HS
• Jun JY
• Park JS

Abstract

The effects of nitric oxide on the vestibular function recovery following unilateral labyrinthectomy (UL) were studied. Sprague-Dawley male rats, treated with nitric oxide liberating agent sodium nitroprusside (SNP) and NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME), were subjected to destruction of the unilateral vestibular apparatus, and then spontaneous nystagmus was observed in the rat. To explore the effects of nitric oxide on the neuronal excitability, whole cell patch clamp technique was applied on isolated medial vestibular nuclear neurons. The frequency of spontaneous nystagmus in SNP treated rats was lesser than that of spontaneous nystagmus in control animals. In contrast, pre-UL treatment with L-NAME resulted in a significant increase in spontaneous nystagmus frequency. In addition, SNP increased the frequency of spontaneous action potential in isolated medial vestibular nuclear neurons. Potassium currents of the vestibular nuclear neurons were inhibited by SNP. After blockade of calcium dependent potassium currents by high EGTA (11 mM) in a pipette solution, SNP did not inhibit outward potassium currents. 1H-[1, 2, 4] oxadiazolo [4, 3-a] quinozalin-1-one (ODQ), a specific inhibitor of soluble guanylyl cyclase, inhibited the effects of SNP on the spontaneous firing and the potassium current. These results suggest that nitric oxide after unilateral labyrin- thectomy would help to facilitate vestibular compensation by inhibiting calcium-dependent potassium currents through increasing intracellular cGMP, and consequently would increase excitability in ipsilateral vestibular nuclear neurons.

Keyword

Vestibular compensation; Nitric oxide; Spontaneous action potential; Potassium current

MeSH Terms

Action Potentials
Animals
Calcium
Compensation and Redress*
Egtazic Acid
Fires
Guanylate Cyclase
Humans
Male
Neurons
NG-Nitroarginine Methyl Ester
Nitric Oxide*
Nitroprusside
Potassium
Rats
Rats, Sprague-Dawley
Recovery of Function
Vestibule, Labyrinth
Calcium
Egtazic Acid
Guanylate Cyclase
NG-Nitroarginine Methyl Ester
Nitric Oxide
Nitroprusside
Potassium