Identification and characterization of an L-type Cav1.2 channel in spiral ligament fibrocytes of gerbil inner ear
Autor: | Cungui Mao, Fenghe Liang, Zhijun Shen, Debra J. Hazen-Martin, Chunyan Qu, Bradley A. Schulte, Wei Hu |
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Rok vydání: | 2004 |
Předmět: |
BK channel
Patch-Clamp Techniques Calcium Channels L-Type Nifedipine Molecular Sequence Data Biology Gerbil Cav1.2 Cellular and Molecular Neuroscience medicine Animals Protein Isoforms Inner ear Molecular Biology Cells Cultured Membrane potential Ligaments Base Sequence Depolarization Anatomy Calcium Channel Blockers Cochlea medicine.anatomical_structure Spiral ligament Biophysics biology.protein Calcium Female sense organs Gerbillinae Sequence Alignment Intracellular |
Zdroj: | Molecular Brain Research. 125:40-46 |
ISSN: | 0169-328X |
Popis: | Intracellular free Ca 2+ levels are critical to the activity of BK channels in inner ear type I spiral ligament fibrocytes. However, the mechanisms for regulating intracellular Ca 2+ levels in these cells are currently poorly understood. Using patch-clamp technique, we have identified a voltage-dependent L-type Ca 2+ channel in type I spiral ligament fibrocytes cultured from gerbil inner ear. With 10 mM Ba 2+ as the conductive cation, an inwardly rectifying current was elicited with little inactivation by membrane depolarization. The voltage activation threshold and the half-maximal voltage activation were −40 and −6 mV, respectively. This inward whole-cell current reached its peak at around 10 mV of membrane potential. The amplitude of the peak current varied among cells ranging from 50 to 274 pA with an average of 132.4±76.2 pA ( n =19); 10 −6 M nifedipine significantly inhibited the inward currents by 90.3±1.2% ( n =11). RT-PCR analysis revealed that cultured type I spiral ligament fibrocytes express the α 1C isoform of the L-type Ca 2+ channels encoded by the Ca v 1.2 gene. The expression of this channel in gerbil inner ear was confirmed by RT-PCR analysis using freshly isolated spiral ligament tissues. The Ca v 1.2 channel may function in conjunction with a previously identified intracellular Ca-ATPase (SERCA) to regulate intracellular free Ca 2+ levels in type I spiral ligament fibrocytes, and thus modulate BK channel activity in these cells. |
Databáze: | OpenAIRE |
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