Roles of Nitric Oxide in Vestibular Compensation.
- Author:
Han Seong JEONG
1
;
Jae Yeoul JUN
;
Jong Seong PARK
Author Information
1. Department of Physiology, Chonnam National University Medical School, Gwangju 501 190, Korea. parkjs@jnu.ac.kr
- Publication Type:Original Article
- Keywords:
Vestibular compensation;
Nitric oxide;
Spontaneous action potential;
Potassium current
- MeSH:
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
- From:The Korean Journal of Physiology and Pharmacology
2003;7(2):73-78
- CountryRepublic of Korea
- Language:English
-
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.
