Effects of pH and Ascorbic Acid on3H-Spiperone and3H-Dihydroalprenolol Binding in Rat Forebrain Homogenates

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Abstract
The binding of the neuroleptic agent 3H-spiperone and the beta-blocker 3H-dihydroalprenolol (3H-DHA) was investigated in rat forebrain homogenates. The pH of the buffer medium was found to specifically affect binding to certain sites. Omission of ascorbic acid from the binding assay influenced binding in a pH-dependent way. Preincubation with a relatively low concentration of ascorbic acid markedly reduced the binding of both ligands except the nonspecific binding of 3H-spiperone. Lipid peroxidation as revealed by malonyldialdehyde formation, was increased by low and decreased by high ascorbic acid concentrations. The possible relationship between changes in number of binding sites and liposolubility is discussed.