Calcium channels triggering transmitter release in the rat medial superiorolive

We used whole cell voltage clamp recordings from neurones in rat auditory b rainstem slices to study the Ca2+ channel types involved in triggering syna ptic glutamate and glycine release in the medial superior olivary nucleus. Glutamate release from the anterior ventral cochlear (aVCN) bushy neurone s ynapse did not involve L-type Ca2+ channels (alpha (1C-D); Ca(V)1.2-1.3), b ut was mediated with similar efficacies by both N-type (alpha (1B); Ca(V)2. 2) and the P/Q-type Ca2+ channels (alpha (1A); Ca(V)2.1). Glycine release f rom the medial nucleus of the trapezoid body (MNTB) synapse was mediated pr edominantly by P/Q-type Ca2+ channels, but with a significant contribution from N-type Ca2+ Channels. Combined application of the P/Q- and N-type Ca2 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 Ca2+ channels (alpha (1E); Ca(V)2.3) to transmitter release, In contrast with aVCN bushy neurone s, MNTB somata lacked both T-(alpha (1G-I); Ca(V)3.1-3.3) and L-type channe ls, but expressed a higher proportion of P/Q-type Ca2+ channels. (C) 2001 E lsevier Science B.V. All rights reserved.