Linked Life Data

12099893

Source:http://linkedlifedata.com/resource/pubmed/id/12099893

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2002-7-8
pubmed:abstractText
N- and P/Q-type voltage dependent calcium channels (VDCCs) mediate transmitter release at neonatal rat neuromuscular junction (NMJ). Thus the neonatal NMJ allows an examination of the coupling of different subtypes of VDCCs to the release process at a single synapse. We studied calcium dependence of transmitter release mediated by each channel by blocking with omega-conotoxin GVIA the N-type channel or with omega-agatoxin IVA the P/Q-type channel while changing the extracellular calcium concentration ([Ca2+]o). Transmitter release mediated by P/Q-type VDCCs showed steeper calcium dependence than N-type mediated release (average slope 3.6 +/- 0.09 vs. 2.6 +/- 0.03, respectively). Loading the nerve terminals with 10 microm BAPTA-AM in the extracellular solution reduced transmitter release and occluded the blocking effect of omega-conotoxin GVIA (blockade -2 +/- 9%) without affecting the action of omega-agatoxin IVA (blockade 85 +/- 4%). Both VDCC blockers were able to reduce the amount of facilitation produced by double-pulse stimulation. In these conditions facilitation was restored by increasing [Ca2+]o. The facilitation index (fi) was also reduced by loading nerve terminals with 10 microm BAPTA-AM (fi = 1.2 +/- 0.1). The control fi was 2.5 +/- 0.1. These results show that P/Q-type VDCCs were more efficiently coupled to neurotransmitter release than were N-type VDCCs at the neonatal neuromuscular junction. This difference could be accounted for by a differential location of these channels at the release site. In addition, our results indicate that space-time overlapping of calcium domains was required for facilitation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0953-816X
pubmed:author
pubmed:issnType
Print
pubmed:volume
15
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1874-80
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:12099893-Aging, pubmed-meshheading:12099893-Animals, pubmed-meshheading:12099893-Animals, Newborn, pubmed-meshheading:12099893-Calcium, pubmed-meshheading:12099893-Calcium Channel Blockers, pubmed-meshheading:12099893-Calcium Channels, N-Type, pubmed-meshheading:12099893-Calcium Channels, P-Type, pubmed-meshheading:12099893-Calcium Signaling, pubmed-meshheading:12099893-Cell Differentiation, pubmed-meshheading:12099893-Chelating Agents, pubmed-meshheading:12099893-Edetic Acid, pubmed-meshheading:12099893-Egtazic Acid, pubmed-meshheading:12099893-Electric Stimulation, pubmed-meshheading:12099893-Motor Neurons, pubmed-meshheading:12099893-Muscle, Skeletal, pubmed-meshheading:12099893-Neuromuscular Junction, pubmed-meshheading:12099893-Neurotransmitter Agents, pubmed-meshheading:12099893-Presynaptic Terminals, pubmed-meshheading:12099893-Rats, pubmed-meshheading:12099893-Rats, Wistar, pubmed-meshheading:12099893-Synaptic Transmission, pubmed-meshheading:12099893-Synaptic Vesicles, pubmed-meshheading:12099893-omega-Agatoxin IVA, pubmed-meshheading:12099893-omega-Conotoxin GVIA
pubmed:year
2002
pubmed:articleTitle
Differential Ca2+-dependence of transmitter release mediated by P/Q- and N-type calcium channels at neonatal rat neuromuscular junctions.
pubmed:affiliation
Laboratorio de Fisiología y Biología Molecular, Departamento de Biología, Facultad de Ciencias, Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II 2 do piso, Buenos Aires (1428), Argentina.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't