PT  - JOURNAL ARTICLE
AU  - Reid, Christopher A.
AU  - Clements, John D.
AU  - Bekkers, John M.
TI  - Nonuniform Distribution of Ca<sup>2+</sup> Channel Subtypes on Presynaptic Terminals of Excitatory Synapses in Hippocampal Cultures
AID  - 10.1523/JNEUROSCI.17-08-02738.1997
DP  - 1997 Apr 15
TA  - The Journal of Neuroscience
PG  - 2738--2745
VI  - 17
IP  - 8
4099  - http://www.jneurosci.org/content/17/8/2738.short
4100  - http://www.jneurosci.org/content/17/8/2738.full
SO  - J. Neurosci.1997 Apr 15; 17
AB  - Several subtypes of Ca2+ channel support the release of glutamate at excitatory synapses. We investigated the pattern of colocalization of these subtypes on presynaptic terminals in hippocampal cultures. N-type (conotoxin GVIA-sensitive) or P/Q-type (agatoxin IVA-sensitive) Ca2+ channels were blocked selectively, and the reduction in transmitter release probability (Pr) was measured with MK-801. The antagonists completely blocked release at some terminals, reducedPr at others, and failed to affect the remainder. In contrast, nonselective reduction of presynaptic Ca2+ influx by adding Cd2+ or lowering external Ca2+ reduced Pr uniformly at all terminals. We conclude from these results that the mixture of N-type and P/Q-type channels varies markedly between terminals on the same afferent. The distribution of Ca2+ channel subtypes was the same for high and low Pr terminals. Given that Ca2+ channel subtypes are affected differentially by neuromodulators, these findings lead to the possibility of terminal-specific modulation of synaptic function.