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Titolo:
Ca2+ channels that activate Ca2+-dependent K+ currents in neostriatal neurons
Autore:
Vilchis, C; Bargas, J; Ayala, GX; Galvan, E; Galarraga, E;
Indirizzi:
Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Mexico City 04510, DF, Mexico Univ Nacl Autonoma Mexico Mexico City DF Mexico 04510 y 04510, DF, Mexico
Titolo Testata:
NEUROSCIENCE
fascicolo: 3, volume: 95, anno: 2000,
pagine: 745 - 752
SICI:
0306-4522(2000)95:3<745:CCTACK>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
MUSCARINIC RECEPTORS MODULATE; HIPPOCAMPAL PYRAMIDAL NEURONS; OMEGA-AGATOXIN-TK; POTASSIUM CHANNELS; CALCIUM CURRENTS; N-TYPE; PHYSIOLOGICAL ROLES; FIRING BEHAVIOR; SPINY NEURONS; VAGAL NEURONS;
Keywords:
calcium currents; basal ganglia; calcium-activated potassium currents; neostriatum; afterhyperpolarization; firing pattern;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Bargas, J Univ Nacl Autonoma Mexico, Inst Fisiol Celular, POB 70-253, Mexico City 04510, DF, Mexico Univ Nacl Autonoma Mexico POB 70-253 Mexico City DF Mexico 04510
Citazione:
C. Vilchis et al., "Ca2+ channels that activate Ca2+-dependent K+ currents in neostriatal neurons", NEUROSCIENC, 95(3), 2000, pp. 745-752

Abstract

It is demonstrated that not all voltage-gated calcium channel types expressed in neostriatal projection neurons (L, N, P, Q and R) contribute equallyto the activation of calcium-dependent potassium currents. Previous work made clear that different calcium channel types contribute with a similar amount of current to whole-cell calcium current in neostriatal neurons. It has also been shown that spiny neurons posses both "big" and "small" types ofcalcium-dependent potassium currents and that activation of such currents relies on calcium entry through voltage-gated calcium channels. In the present work it was investigated whether all calcium channel types equally activate calcium-dependent potassium currents. Thus, the action of organic calcium channel antagonists was investigated on the calcium-activated outward current. Transient potassium currents were reduced by 4-aminopyridine and sodium currents were blocked by tetrodotoxin. It was found that neither 30 nMomega-Agatoxin-TK, a blocker of P-type channels, nor 200 nM calciseptine or 5 mu M nitrendipine, blockers of L-type channels, were able to significantly reduce the outward current. In contrast, 400 nM omega-Agatoxin-TK, which at this concentration is able to block Q-type channels, and 1 mu M omega-Conotoxin GVIA, a blocker of N-type channels, both reduced outward current by about 50%. These antagonists given together, or 500 nM omega-Conotoxin MWC, a blocker of N- and P/Q-type channels, reduced outward current by 70%. In addition, the N- and P/Q-type channel blockers preferentially reduce theafterhyperpolarization recorded intracellularly. The results show that calcium-dependent potassium channels in neostriatal neurons are preferentially activated by calcium entry through N- and Q-typechannels in these conditions. (C) 1999 IBRO. Published by Elsevier ScienceLtd.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/07/20 alle ore 18:32:06