Comparison of the properties of [3H]-D-2-amino-5-phosphonopentanoic acid and [3H]-DL-2-amino-7-phosphonoheptanoic acid binding to homogenates of rat cerebral cortex.

Abstract

1. The pharmacology and ionic regulation of [3H]-2-D-2-amino-5-phosphonopentanoic acid ([3H]-D-AP5) and [3H]-DL-2-amino-7-phosphonoheptanoic acid ([3H]-DL-AP7) binding to homogenates of rat cerebral cortex were examined using radioligand binding methodology. 2. Both [3H]-D-AP5 and [3H]-DL-AP7 labelled a single population of binding sites with dissociation constants of 0.39 and 1.8 mumol/l, respectively. The density of binding sites found with [3H]-DL-AP7 was 13 times greater than that found with [3H]-D-AP5. 3. The ionic requirements of the [3H]-D-AP5 binding site in the presence of chloride were such that calcium acetate enhanced binding, while magnesium and sodium acetate both decreased bin..