Effects of increasing Ca2+ channel-vesicle separation on facilitation at the crayfish inhibitory neuromuscular junction.

ABSTRACT: We investigated the mechanism of facilitation at the crayfish inhibitory neuromuscular junction before and after blocking P-type Ca(2+) channels. P-type channels have been shown to be closer to releasable synaptic vesicles than non-P-type channels at this synapse. Prior to the block of P-type channels, facilitation evoked by a train of 10 action potentials at 100 Hz was increased by application of 40 mM [Mg(2+)](o), but decreased by pressure-injected EGTA. Blocking P-type channels with 5 nM omega-Aga IVA, which reduced total Ca(2+) influx and release to levels comparable to that recorded in 40 mM [Mg(2+)](o), did not change the magnitude of facilitation. We explored whether this observation could be attributed to the buffer saturation model of facilitation, since increasing the Ca(2+) chan

SUBMITTER: Allana TN 

PROVIDER: S-EPMC2577849 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature