PMID: 7240171Jun 10, 1981

Proton: substrate stoichiometries during active transport of biogenic amines in chromaffin ghosts

The Journal of Biological Chemistry
R G JohnsonA Scarpa


The relationship between the electrochemical proton gradient (delta mu-H+) and the electrochemical gradient for biogenic amines (delta mu-A) was investigated in isolated chromaffin ghosts free of endogenous components and gradients. The addition of ATP to a ghost suspension resulted in the generation of a large proton concentration gradient (delta pH), acidic inside (measured by [14C]-methylamine distribution), and a large proton electrical gradient (delta psi), positive inside (measured by [14C]-thiocyanate distribution). In the presence of this large electrochemical proton gradient, the accumulation of [14C]5-hydroxytryptamine (serotonin) and other biogenic amines rapidly reached an apparent steady state level. Collapse of the proton gradients after steady state levels were achieved resulted in the efflux of the accumulated amines. Uptake in the presence of a delta psi alone produced an amine gradient equal to the magnitude of the delta psi, while in the presence of a delta pH alone biogenic amine distribution was equal to twice the magnitude of the delta pH. Using additions of ammonia or thiocyanate, it was possible to vary the magnitude of the electrochemical proton gradient over a wide range of values; the driving force fo...Continue Reading

Related Concepts

Ammonium Sulfate
Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
Chromaffin Granule
Chromaffin System
Hydrogen-Ion Concentration
Intracellular Membranes

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