Uptake of (/sup 3/H)serotonin into plasma membrane vesicles from mouse cerebral cortex
Preparations of plasma membrane vesicles were used as a tool to study the properties of the serotonin transporter in the central nervous system. The vesicles were obtained after hypotonic shock of synaptosomes purified from mouse cerebral cortex. Uptake of (/sup 3/H)serotonin had a Na/sup +/-dependent and Na/sup +/-independent component. The Na/sup +/-dependent uptake was inhibited by classical blockers of serotonin uptake and had a K/sub m/ of 63-180 nM, and a V/sub max/ of 0.1-0.3 pmol mg/sup -1/ s/sup -1/ at 77 mM Na/sup +/. The uptake required the presence of external Na/sup +/ and internal K/sup +/. Replacement of Cl/sup -/ by other anions (NO/sub 2//sup -/, S/sub 2/O/sub 3//sup 2 -/) reduced uptake appreciably. Gramicidin prevented uptake. Although valinomycin increased uptake somewhat, the membrane potential per se could not drive uptake because no uptake was observed when a membrane potential was generated by the SCN/sup -/ ion in the absence of internal K/sup +/ and with equal (Na/sup +/) inside and outside. The increase of uptake as a function of (Na/sup +/) indicated a K/sub m/ for Na/sup +/ of 118 mM and a Hill number of 2.0, suggesting a requirement of two sodium ions for serotonin transport. The present results are accommodated very well by the model developed for porcine platelet serotonin transport except for the number of sodium ions that are required for transport.
- Research Organization:
- Nathan S. Kline Institute for Psychiatric Research, New York, NY (USA)
- OSTI ID:
- 6838257
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 263:13
- Country of Publication:
- United States
- Language:
- English
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MEMBRANE TRANSPORT
BIOCHEMICAL REACTION KINETICS
SEROTONIN
UPTAKE
TRITIUM COMPOUNDS
CELL MEMBRANES
CEREBRUM
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ALKALI METAL COMPOUNDS
AMINES
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
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CENTRAL NERVOUS SYSTEM
DRUGS
HETEROCYCLIC COMPOUNDS
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INDOLES
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MEMBRANES
NERVOUS SYSTEM
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRROLES
RADIOPROTECTIVE SUBSTANCES
REACTION KINETICS
RODENTS
SYMPATHOMIMETICS
TRYPTAMINES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques