Glutamate binding in the rat cerebral cortex during ontogeny.
Two binding sites for L-glutamate have been identified on adult rat brain cortical membranes. One of these sites is Na+-dependent with Kd of 1.3 micro M and a Bmax of 210 pmol/mg protein. The other is Na+-independent with a Kd of 0.37 micro M and Bmax of 6.2 pmol/mg protein. There is a sharp rise in total number of Na+-independent sites per cortex up to 20 days postnatally followed by a more gradual rise to adult levels at 50 days. Na+-dependent binding is also low at birth rising to a peak at 20 days followed by a drop in total levels of binding to 30 days and then a very sharp rise up to 50 days. The kinetics of binding at 20 days gives a Kd for the Na+-dependent site of 1.77 micro M and a Bmax of 82 pmol/mg protein. The Na+-independent site at 20 days has a Kd = 1.3 micro M and Bmax of 8.47 pmol/mg protein. The ability of several acidic amino acid analogues to displace specifically bound L-glutamate was investigated by estimating IC50 values at 20 and 50 days of age. The Na+-independent site is stereospecific for L-glutamate at both ages, but will also interact with L-aspartate at 20 days. The Na+-dependent site has a similar affinity for L- and D-glutamate and L-aspartate at 50 days. The L-glutamate analogue kainate will not displace any bound L-glutamate.
D000375:Aging; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000254:growth & development* / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D007700:Kinetics; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology
D000596:Amino Acids; D005971:Glutamates; D011956:Receptors, Cell Surface; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; D018698:Glutamic Acid; D012964:Sodium