Linked Life Data

2842467

Source:http://linkedlifedata.com/resource/pubmed/id/2842467

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1988-10-7
pubmed:abstractText
The pharmacological properties of the interaction between the excitatory amino acid (EAA) analogs kainate and N-methyl-D-aspartate (NMDA) have been examined on the isolated rat retinal ganglion cell preparation. In addition, we have studied the effects on this interaction of 2 noncompetitive NMDA antagonists, the dissociative anesthetic phencyclidine (PCP) and the anticonvulsant MK-801. Electrophysiological measurements were performed with the whole-cell patch-clamp technique on cultured ganglion cells that had been back-labeled with a fluorescent dye. Whereas only 69% of the cells showed responses to NMDA (in the absence of extracellular Mg2+), every ganglion cell responded to kainate under the same conditions. When a given cell was voltage-clamped at -60 mV, the large inward currents elicited by 125 microM kainate generally exceeded the responses evoked by 200 microM NMDA, when present, by 1 or 2 orders of magnitude. There was a poor correlation between the magnitudes of the currents produced by both agonists for the population of cells tested. Furthermore, NMDA proved to be an antagonist for the kainate receptor binding site. Without influencing the kainate-activated currents, PCP (75 microM) and MK-801 (20 microM) completely and reversibly blocked the responses evoked by NMDA (200 microM), independent of the membrane holding potential. The degree of block produced by a submaximal concentration of either antagonist was accentuated by increasing the concentration of NMDA. The independence of NMDA and kainate currents was examined. In the presence of NMDA and PCP (or MK-801), kainate-induced responses were comparable in amplitude to those generated by the application of kainate and NMDA together. Thus, kainate continued to produce an increase in membrane conductance at a time when NMDA-activated currents were blocked by either antagonist. The NMDA antagonism of kainate-induced currents was shown to be constant and independent of PCP or MK-801. Our results suggest that the 2 EAA analogs might not share a common ionophore, but rather activate separate receptor-ion channel complexes in rat retinal ganglion cell membranes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0270-6474
pubmed:author
pubmed:issnType
Print
pubmed:volume
8
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2895-906
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
The interaction of agonists and noncompetitive antagonists at the excitatory amino acid receptors in rat retinal ganglion cells in vitro.
pubmed:affiliation
Max-Planck-Institut für Hirnforschung, Frankfurt/M., FRG.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't