Dopaminergic receptors in cat brain. Action of triton X-100 on [3H]spiroperidol binding and localization in relation to the synaptic region.
[3H]Spiroperidol binding was used to assay dopaminergic receptors in synaptosomal membranes isolated from basal ganglia of cat brain. In addition to the usual filtration, a special centrifugation technique was developed which has some advantages for ligands with high non-specific binding. The specific binding to control membranes showed a high affinity binding site with KD 0.99 nM and Bmax 445 fmol/mg protein, both determined by Scatchard analysis. Addition of 10(-5) -10(-3)% Triton X-100 increased the Bmax of the high affinity binding site without a change in KD. With higher concentrations of detergent (10(-2) -10 (-1)% there was inhibition of binding. Both the activation and the inhibition of binding were reversed by washing of the detergent; but the reversal of the activation was accompanied by a decrease in affinity. The binding to synaptosomal membranes treated with 10(-1) - 10(-2)% Triton X-100 and then washed led to a loss of receptors probably present in the presynaptic membrane. These and other results suggest that dopaminergic receptors are localized both pre- and postsynaptically in relation to the synaptic region.
D000818:Animals; D001479:Basal Ganglia / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002090:Butyrophenones / Q000378:metabolism*; D002415:Cats; D066298:In Vitro Techniques; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011954:Receptors, Dopamine / Q000187:drug effects*; D013134:Spiperone / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*
D002090:Butyrophenones; D011954:Receptors, Dopamine; D011092:Polyethylene Glycols; D013134:Spiperone; D017830:Octoxynol