RGD Reference Report - Voltage-gated calcium channels in adult rat inferior colliculus neurons. - Rat Genome Database

RGD Reference Report - Voltage-gated calcium channels in adult rat inferior colliculus neurons. - Rat Genome Database

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Voltage-gated calcium channels in adult rat inferior colliculus neurons.
Authors:	N'Gouemo, P Morad, M
Citation:	N'Gouemo P and Morad M, Neuroscience 2003;120(3):815-26.
RGD ID:	1299353
Pubmed:	PMID:12895521 (View Abstract at PubMed)
The inferior colliculus (IC) plays a key role in the processing of auditory information and is thought to be an important site for genesis of wild running seizures that evolve into tonic-clonic seizures. IC neurons are known to have Ca(2+) channels but neither their types nor their pharmacological properties have been as yet characterized. Here, we report on biophysical and pharmacological properties of Ca(2+) channel currents in acutely dissociated neurons of adult rat IC, using electrophysiological and molecular techniques. Ca(2+) channels were activated by depolarizing pulses from a holding potential of -90 mV in 10 mV increments using 5 mM barium (Ba(2+)) as the charge carrier. Both low (T-type, VA) and high (HVA) threshold Ca(2+) channel currents that could be blocked by 50 microM cadmium, were recorded. Pharmacological dissection of HVA currents showed that nifedipine (10 microM, L-type channel blocker), omega-conotoxin GVIA (1 microM, N-type channel blocker), and omega-agatoxin TK (30 nM, P-type channel blocker) partially suppressed the current by 21%, 29% and 22%, respectively. Since at higher concentration (200 nM) omega-agatoxin TK also blocks Q-type channels, the data suggest that Q-type Ca(2+) channels carry approximately 16% of HVA current. The fraction of current (approximately 12%) resistant to the above blockers, which was blocked by 30 microM nickel and inactivated with tau of 15-50 ms, was considered as R-type Ca(2+) channel current. Consistent with the pharmacological evidences, Western blot analysis using selective Ca(2+) channel antibodies showed that IC neurons express Ca(2+) channel alpha(1A), alpha(1B), alpha(1C), alpha(1D), and alpha(1E) subunits. We conclude that IC neurons express functionally all members of HVA Ca(2+) channels, but only a subset of these neurons appear to have developed functional LVA channels.

Objects referenced in this article

Gene	Cacna1a	calcium voltage-gated channel subunit alpha1 A	Rattus norvegicus
Gene	Cacna1b	calcium voltage-gated channel subunit alpha1 B	Rattus norvegicus
Gene	Cacna1c	calcium voltage-gated channel subunit alpha1 C	Rattus norvegicus
Gene	Cacna1d	calcium voltage-gated channel subunit alpha1 D	Rattus norvegicus
Gene	Cacna1e	calcium voltage-gated channel subunit alpha1 E	Rattus norvegicus

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