Altered Synaptic Synchrony in Motor Nerve Terminals Lacking P/Q-Calcium Channels

RAFAEL S. DEPETRIS, SILVANA I. NUDLER, OSVALDO D. UCHITEL, AND FRANCISCO J. URBANO

SYNAPSE

Año: 2008 vol. 62 p. 466 - 471

0887-4476

The variance in synaptic delays among endplate potentials events(referred here as jitter) was measured to study the contribution of voltage dependentcalcium channels to transmission synchronicity in neuromuscular synapses from wildtype and a-1A knockout mice (i.e., lacking P/Q type calcium channels). Knockout synapsespresented higher jitter values than wild type ones under a wide range of extracellularcalcium concentration ([Ca21]o) values. Accordingly, wild type synapses showedless synchronic neurotransmitter release when P/Q type calcium channels were partiallyblocked as well as under lower [Ca21]o. In the knockout synapses, N-type calciumchannels mediated neurotransmitter release in a more temporally precise waythan the R-type ones. Our results suggest that the type of calcium channels mediatingtransmitter release influenced the degree of synaptic synchrony. Thus, these resultsprovide insight on the mechanisms underlying several pathologies associated with P/Qtype calcium channels.