Cations Differentially Affect Subpopulations of L-Glutamate Receptors in Rat Synaptic Plasma Membranes

摘要

Several cations were examined for their ability to specifically affect one of the 3 L-glutamate (L-Glu) binding sites in rat forebrain synaptic plasma membranes (i.e. Na(+)-dependent, Cl(-)-dependent and Cl(-)-independent). Na(+)-dependent binding was potently inhibited by K(+) and NH1-ions. Other monovalent cations tested (Cs-.Li-.triethylammonium) had no effect on this binding site. Ployvalent cations (Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Cr(3+) also had little effect on the Na+-dependent L-Glu binding site. Cl(-)-dependent L-Glu binding was potently inhibited by Na(+) ions but was not affected by other monovalentions. All of the divalent cations were potent inhibitors of both Cl(-)-dependent and -independent binding. The results show that these binding sites of L-Glu can be distinguished by their response to cations and suggest possible novel modes of regulation in vivo.