Calcium channels triggering transmitter release in the rat medial superior olive.
We used whole cell voltage clamp recordings from neurones in rat auditory brainstem slices to study the Ca(2+) channel types involved in triggering synaptic glutamate and glycine release in the medial superior olivary nucleus. Glutamate release from the anterior ventral cochlear (aVCN) bushy neurone synapse did not involve L-type Ca(2+) channels (alpha(1C-D); Ca(V)1.2-1.3), but was mediated with similar efficacies by both N-type (alpha(1B); Ca(V)2.2) and the P/Q-type Ca(2+) channels (alpha(1A); Ca(V)2.1). Glycine release from the medial nucleus of the trapezoid body (MNTB) synapse was mediated predominantly by P/Q-type Ca(2+) channels, but with a significant contribution from N-type Ca(2+) channels. Combined application of the P/Q- and N-type Ca(2+) channel toxins, omega-agatoxin IVA and omega-conotoxin GVIA, left a very small remnant of both the inhibitory and excitatory postsynaptic currents, probably reflecting a minimal contribution of R-type Ca(2+) channels (alpha(1E); Ca(V)2.3) to transmitter release. In contrast with aVCN bushy neurones, MNTB somata lacked both T- (alpha(1G-I); Ca(V)3.1-3.3) and L-type channels, but expressed a higher proportion of P/Q-type Ca(2+) channels.
Barnes-Davies
M
M
Ion Channel Group, Department of Cell Physiology and Pharmacology, University of Leicester, P.O. Box 138, LE1 9HN, Leicester, UK. mb27@leicester.ac.uk
Owens
S
S
Forsythe
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ID
D000818:Animals; D015220:Calcium Channels / Q000145:classification / Q000502:physiology*; D017626:Cochlear Nucleus / Q000378:metabolism; D004553:Electric Conductivity; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials; D066298:In Vitro Techniques; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009847:Olivary Nucleus / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000502:physiology
D015220:Calcium Channels; D018377:Neurotransmitter Agents