Characterization of cocaine-sensitive dopamine uptake in PC12 cells

Neurochem Int. 1992 Dec;21(4):521-6. doi: 10.1016/0197-0186(92)90083-4.

Abstract

Dopamine uptake in rat pheochromocytoma (PC12) cells is a carrier-mediated process which follows Michaelis-Menten kinetics. Uptake was saturable with an apparent Km of 0.71 microM for dopamine and a Vmax of 3.2 pmol/2 x 10(5) cells/min. The rank order of potency for various amines was norepinephrine > or = dopamine > epinephrine. Uptake increased with increasing temperature and showed a sharp break in the Arrhenius plot at 27.5 degrees C. The Q10 was 1.39 above and 2.95 below 27.5 degrees C. Cocaine inhibited uptake in a dose-dependent manner with a Ki of 0.97 microM. The presence of cocaine lowered the apparent Km but did not affect the Vmax, indicating competitive inhibition. Tunicamycin inhibited [3H]dopamine accumulation in a dose- and time-dependent fashion suggesting the dopamine uptake site in PC12 cells is an asparagine-linked glycoprotein. Kinetic analysis showed a decrease in Vmax but not in the apparent Km after tunicamycin treatment, consistent with the notion that tunicamycin treatment results in the loss of a substantial amount of active carrier molecules.

MeSH terms

  • Animals
  • Binding, Competitive
  • Cocaine / pharmacology*
  • Dopamine / metabolism*
  • Epinephrine / metabolism
  • Hot Temperature
  • Kinetics
  • PC12 Cells / metabolism*
  • Rats
  • Thermodynamics
  • Tunicamycin / pharmacology

Substances

  • Tunicamycin
  • Cocaine
  • Dopamine
  • Epinephrine