Abstract
Guanosine triphosphate (GTP) and diphosphate (GDP) decrease the binding of the agonist [3H]serotonin (5-HT) to serotonin receptors in mammalian brain membranes. Binding of the antagonist [3H]spiroperidol is not affected by guanine nucleotides while the mixed agonist-antagonist [3H]lysergic acid diethylamide ([3H]LSD) is affected in an intermediate manner. GTP lowers the apparent affinity of [3H]5-HT for its receptors without changing the number of binding sites. Both the association and dissociation rates of [3H]5-HT are increased by GTP. The potency of 5-HT agonists in competing for [3H]5-HT but not [3H]LSD or [3H]spiroperidol binding sites is decreased by GTP. Competition by partial agonists and antagonists for [3H]5-HT binding sites is not affected by GTP.
ACKNOWLEDGMENTS We thank Pamela Morgan for manuscript preparation.
- Copyright © 1979 by Academic Press, Inc.
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