"Specific" [(3)H]8-OH-DPAT binding to glass fiber filter paper: Implications for the analysis of serotonin binding site subtypes.
The effect of buffer constituents on [(3)H]8-OH-DPAT binding to glass fiber filter paper was examined. Apparent "specific" [(3)H]8-OH-DPAT binding to glass fiber filter paper can be demonstrated when the radioligand binding assay is performed in the absence of 0.1% ascorbate. This artifactual "specific" binding is time dependent and appears to saturate. In addition, drug competition studies reveal complex interactions with [(3)H]8-OH-DPAT binding to glass fiber filter paper in the absence of ascorbate. Both 5-HT and chlorimipramine appear to "complete" for the sites labeled by [(3)H]8-OH-DPAT while both d-LSD and methysergide cause an increase in the [(3)H]8-OH-DPAT binding to glass fiber filter paper at micromolar concentrations. These data indicate that [(3)H]8-OH-DPAT binding to glass fiber filter paper may lead to misinterpretation of radioligand data obtained using brain homogenates in the absence of ascorbate.
Demopulos
C M
CM
Department of Neurology and Pharmacology, Stanford University Medical Center, Stanford, CA 94305, U.S.A. Tel.: (415) 723-8137.
Peroutka
S J
SJ