Stoichiometry of H+-linked dopamine transport in chromaffin granule ghosts.
A proton-translocating adenosinetriphosphatase in adrenal medullary chromaffin granule ghosts can generate either a membrane potential (inside positive) or a pH gradient (inside acid). Dopamine uptake occurs in response to both the membrane potential and the pH gradient. The natural logarithm of the dopamine concentration gradient [In (Din/Dout)] is linearly related to the membrane potential with a slope of F/(RT). This dependence is not affected by the pH of the medium. In (Din/Dout) is linearly dependent on In ([H+]in/[H+]out) with a slope of 2. These results indicate that dopamine is taken up via an exchange diffusion or antiport mechanism. The stoichiometry of this exchange is two H+/dopamine cation and is independent of pH.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002417:Cattle; D002837:Chromaffin Granules / Q000187:drug effects / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials; D011188:Potassium / Q000494:pharmacology; D006180:Proton-Translocating ATPases
D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases; D011188:Potassium; D004298:Dopamine