Role of ions and membrane potential in uptake of serotonin into plasma membrane vesicles from mouse brain

Biochem Pharmacol. 1989 Jul 1;38(13):2091-7. doi: 10.1016/0006-2952(89)90062-2.

Abstract

Plasma membrane vesicle preparations from mouse cerebral cortex actively accumulated [3H]serotonin upon the imposition of a K+ gradient (in greater than out), a Na+ gradient (out greater than in), and the presence of external Cl-. Maximal stimulation of uptake by internal K+ occurred at 15 mM and half-maximal stimulation at 2 mM. Internal K+ did not enhance uptake merely via generation of a membrane potential because simultaneous parallel increases in internal and external K+ concentration also stimulated uptake. External Cl- increased serotonin uptake with a Km of 18 mM and a Hill number of 1.0, suggesting a requirement for one chloride ion for transport. Uptake could not be driven by internal H+ instead of K+. Estimation of the membrane potential by the distribution of triphenylmethylphosphonium ion showed a modest effect of valinomycin (1-20 microM) in increasing the potential from -19 to -31 mV accompanied by an increase in serotonin uptake. Proton ionophores prevented this effect of valinomycin and, by themselves, reduced the potential to -6 mV, but did not affect serotonin transport. A model is proposed for serotonin transport in brain plasma membrane vesicles that is similar to the model for porcine blood platelet vesicles as far as electroneutrality and stimulation by K+, Na+, and Cl- are concerned, but that is different in substitution of internal H+ for K+.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Membrane / drug effects
  • Cell Membrane / physiology
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / physiology*
  • Chlorides / pharmacology*
  • Female
  • Kinetics
  • Male
  • Membrane Potentials / drug effects
  • Mice
  • Mice, Inbred BALB C
  • Potassium / pharmacology*
  • Serotonin / metabolism*
  • Sodium / pharmacology*
  • Synaptosomes / drug effects
  • Synaptosomes / physiology*
  • Valinomycin / pharmacology

Substances

  • Chlorides
  • Valinomycin
  • Serotonin
  • Sodium
  • Potassium