Chonnam Med J.  2011 Dec;47(3):155-159. 10.4068/cmj.2011.47.3.155.

Effects of Cyclic Nucleotide-Gated Channels in Vestibular Nuclear Neurons

• Heo T
• Jang S
• Jeong HS
• Park JS

• KMID: 2172224
• DOI: http://doi.org/10.4068/cmj.2011.47.3.155

Abstract

This study was designed to investigate the effects an 8-Br-cGMP on the neuronal activity of rat vestibular nuclear cells. Sprague-Dawley rats aged 14 to 16 days were decapitated under ether anesthesia. After treatment with pronase and thermolysin, the dissociated vestibular nuclear cells were transferred into a chamber on an inverted microscope. Spontaneous action potentials and potassium currents were recorded by standard patch-clamp techniques under current and voltage-clamp modes. Twelve vestibular nuclear cells revealed excitatory responses to 1-5 microM of 8-Br-cGMP, and 3 neurons did not respond to 8-Br-cGMP. Whole potassium currents of vestibular nuclear cells were decreased by 8-Br-cGMP (n=12). After calcium-dependent potassium currents were blocked by tetraethylammonium, the potassium currents were not decreased by 8-Br-cGMP. These experimental results suggest that 8-Br-cGMP changes the neuronal activity of vestibular nuclear cells by blocking the calcium-dependent potassium currents that underlie the afterhyperpolarization.

Keyword

Nucleotides, Cyclic; Vestibule; Neurons

MeSH Terms

Action Potentials
Aged
Anesthesia
Animals
Ether, Ethyl
Humans
Neurons
Nucleotides, Cyclic
Patch-Clamp Techniques
Potassium
Pronase
Rats
Rats, Sprague-Dawley
Tetraethylammonium
Thermolysin
Ether, Ethyl
Nucleotides, Cyclic
Potassium
Pronase
Tetraethylammonium
Thermolysin

Figure

• 

  FIG. 1 Excitatory effects of 8-Br-cGMP on spontaneous activity of rat medial vestibular nuclear neurons. 8-Br-cGMP increased the firing rate and decreased the membrane potential and the amplitude of afterhyperpolarization.

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  FIG. 2 Effects of 8-Br-cGMP on the outward potassium currents in medial vestibular nuclear neurons. In each panel, the cell was held at -70 mV and test depolarizations with durations of 400 ms were applied from -60 mV to +40 mV in 10-mV increments. The 8-Br-cGMP decreased the outward potassium currents in a dose-dependent manner.

• 

  FIG. 3 Effects of 8-Br-cGMP on the tetraethylammonium-treated potassium currents. The 8-Br-cGMP did not change the TEA-treated potassium currents of rat medial vestibular nuclear neurons.

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