Chonnam Med J.  2005 Aug;41(2):121-129.

Characteristics of Calcium Currents of the Medial Vestibular Nuclear Neuron in Rats

• Jeong HS
• Kim JH
• Kang KW
• Jang SJ
• Park J
• Jang MJ
• Huang M
• Park JS

Abstract

This study was designed to identify and characterize inward calcium currents in acutely isolated medial vestibular nuclear neurons. Whole-cell voltage clamp technique was applied to the medial vestibular nuclear neurons of rats. When cells were held at -80 mV and depolarized from -50 mV to +20 mV in 10 mV increments, sustained inward currents were evoked. The currents evoked by depolarizing pulses peaked around 475+/-55.86 pA at +10 mV. Replacement of external Ca2+ (5 mM) with Ba2+ (10 mM) increased the amplitude of currents about 2 folds. However, replacement of external Ca2+ with Cd2+ (2 mM) almost abolished the inward calcium currents. Changing the holding potential from -80 mV to -40 mV decreased the current amplitude. The application of nicardipine (4micrometer) reduced the long-lasting inward current. The application of flunarizine (4micrometer) reduced transient inward current. These inhibitions produced by nicardipine and flunarizine were associated with a small positive shift of the calcium channel activation curve. The above experimental results suggest that medial vestibular nuclear neurons have both low-voltage-activated and high-voltage-activated Ca2+ channel subtypes. These ionic currents might have an essential role in regulating membrane excitability in the vestibular nuclear neuron.

Keyword

Calcium channel; Vestibular nuclei; Rat

MeSH Terms

Animals
Calcium Channels
Calcium*
Flunarizine
Membranes
Neurons*
Nicardipine
Rats*
Vestibular Nuclei
Calcium
Calcium Channels
Flunarizine
Nicardipine