RT Journal Article SR Electronic T1 Nonuniform Distribution of Ca2+ Channel Subtypes on Presynaptic Terminals of Excitatory Synapses in Hippocampal Cultures JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 2738 OP 2745 DO 10.1523/JNEUROSCI.17-08-02738.1997 VO 17 IS 8 A1 Reid, Christopher A. A1 Clements, John D. A1 Bekkers, John M. YR 1997 UL http://www.jneurosci.org/content/17/8/2738.abstract 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.