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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
1
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pubmed:dateCreated |
1995-11-29
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pubmed:abstractText |
1. The responses of guinea pig trigeminal motoneurons (TMNs) to N-methyl-D,L-aspartate (NMA) were studied using brain stem slice preparations and whole cell patch-clamp (n = 89) or conventional microelectrode (n = 22) recording techniques. The primary goals of this study were to determine whether N-methyl-D-aspartate (NMDA) receptor activation would produce spontaneous bursting activity in TMNs and, if so, the underlying mechanisms responsible for the generation of these bursts. 2. Bath-applied NMA (100-300 microM, n = 80) in standard perfusion medium elicited depolarization, increase in apparent input resistance (Rinp), and rhythmic burst discharges (1-90 s in duration) from TMNs. These effects were blocked by the NMDA receptor antagonist DL-2-amino-5-phosphonopentanoic acid (AP5, 30 microM, n = 6), but not by the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5-10 microM, n = 10). Furthermore, the burst-inducing effect of NMA was not mimicked by the non-NMDA receptor agonists kainate (KA, 5-10 microM, n = 6) and (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA, 5-10 microM, n = 5). 3. In tetrodotoxin (TTX) treatment conditions (n = 13), NMA elicited depolarization, an increase in apparent Rinp, and rhythmic membrane potential oscillations without action potential bursts (i.e., plateau potentials), suggesting that the effects of NMA observed in the TTX-free condition resulted from activation of postsynaptic NMDA receptors. 4. Graded depolarization of neurons (n = 20) by intracellular direct current injection generally led to a graded increase in frequency and duration of the NMA-induced bursts and plateau potentials until these rhythmic events eventually became transformed into continuous spike discharge and maintained depolarization, respectively. Removal of Mg2+ from the perfusion medium (n = 11) also turned the bursts and plateau potentials into continuous spike discharge and maintained depolarization, respectively. 5. The effects of NMA on the current-voltage (I-V) curve after a depolarizing ramp voltage-clamp command (15-20 mV/s) were examined (n = 40). Under NMA (100-300 microM) conditions, the I-V relationship exhibited a region of negative slope conductance (NSC) between -60 and -35 mV, thus making the I-V relationship N-shaped. The NSC was abolished by AP5 (30 microM, n = 8), but not by CNQX (5-10 microM, n = 6). The I-V relationship in AMPA (3-10 microM, n = 5) or KA (3-10 microM, n = 5) was almost linear between -80 and -30 mV.(ABSTRACT TRUNCATED AT 400 WORDS)
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/2-Amino-5-phosphonovalerate,
http://linkedlifedata.com/resource/pubmed/chemical/Excitatory Amino Acid Agonists,
http://linkedlifedata.com/resource/pubmed/chemical/Magnesium,
http://linkedlifedata.com/resource/pubmed/chemical/N-Methylaspartate,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, N-Methyl-D-Aspartate,
http://linkedlifedata.com/resource/pubmed/chemical/Tetrodotoxin
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pubmed:status |
MEDLINE
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pubmed:month |
Jul
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pubmed:issn |
0022-3077
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
74
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
334-46
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:7472335-2-Amino-5-phosphonovalerate,
pubmed-meshheading:7472335-Animals,
pubmed-meshheading:7472335-Electrophysiology,
pubmed-meshheading:7472335-Excitatory Amino Acid Agonists,
pubmed-meshheading:7472335-Guinea Pigs,
pubmed-meshheading:7472335-Magnesium,
pubmed-meshheading:7472335-Male,
pubmed-meshheading:7472335-Membrane Potentials,
pubmed-meshheading:7472335-Microelectrodes,
pubmed-meshheading:7472335-Motor Neurons,
pubmed-meshheading:7472335-N-Methylaspartate,
pubmed-meshheading:7472335-Patch-Clamp Techniques,
pubmed-meshheading:7472335-Potassium Channels,
pubmed-meshheading:7472335-Receptors, N-Methyl-D-Aspartate,
pubmed-meshheading:7472335-Tetrodotoxin,
pubmed-meshheading:7472335-Trigeminal Nerve
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pubmed:year |
1995
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pubmed:articleTitle |
NMDA-induced burst discharge in guinea pig trigeminal motoneurons in vitro.
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pubmed:affiliation |
Department of Physiological Science, University of California at Los Angeles 90024, USA.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, U.S. Gov't, P.H.S.
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