Neuroscience 2003 Abstract
| Presentation Number: | 705.1 |
|---|---|
| Abstract Title: | Calcium channels responsible for GABA release in striatal inhibitory transmission. |
| Authors: |
Tecuapetla, F.*1
; Guzmán, J. N.1
; Carrillo-Reid, L.1
; Tapia, D.1
; Bargas, J.1
; Galarraga, E.1
1Biofísica, Instituto de Fisiología Celular, México, Mexico |
| Primary Theme and Topics |
Motor Systems - Basal Ganglia -- Physiology of transmitters and receptors |
| Secondary Theme and Topics | Motor Systems<br />- Basal Ganglia<br />-- Cell discharge |
| Session: |
705. Basal Ganglia: Transmitters & Receptors I Poster |
| Presentation Time: | Tuesday, November 11, 2003 1:00 PM-2:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # G14 |
| Keywords: | striatum, gabaergic, calcium channel, synaptic transmission |
CALCIUM CHANNELS RESPONSIBLE FOR STRIATAL INHIBITORY TRANSMISSION. F. Tecuapetla, J.N. Guzman, L. Carrillo-Reid, D. Tapia, J. Bargas, E. Galarraga*. Instituto de Fisiologia Celular UNAM PO Box 70-253, Mexico City. Voltage-dependent Ca channels as P/Q and N types mediate transmitter release during synaptic transmission. Evoked GABAergic postsynaptic currents (eIPSCs) were recorded on spiny neurons using the whole-cell voltage-clamp technique. Previous work (Guzman et al, SFN 2002) has shown that eIPSCs in response to intrastriatal stimulation mainly come from interneurons whereas those evoked by antidromic stimulation from the pallidum come from axon collaterals that interconnect spiny cells. The P/Q-type Ca channel antagonist, agatoxin TK (400 nM), blocked most eIPSCs coming from both interneurons (90%) and axon collaterals (95%), whereas the N-type calcium channel antagonist, conotoxin GVIA (1 microM), only produced a partial block of all eIPSCs. It blocked 70% of axon collaterals eIPSCs, whereas eIPSCs from interneurons had very different sensitivities. One group exhibited a partial block of 60% and other a partial block of about 21%. It is concluded that: a) There is participation of both N- and P/Q-types of Ca channels in all types of inhibitory transmission, b) There is superadditivity (addition of block by agatoxin and conotoxin is more than 100%) , c) Blockade by agatoxin of near 100% suggests that P/Q-type channels are the most important, d) The importance of N-type channels varies in different synaptic terminals; probably correlating with interneuron class.
Supported by DGAPA: IN202300/IN202100; CONACyT: 31839-N The Millenium Research Initiative: W-8072/35806-N
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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