PMID: 438157May 25, 1979

Protonmotive force and catecholamine transport in isolated chromaffin granules

The Journal of Biological Chemistry
R G Johnson, A Scarpa

Abstract

The effect of the transmembrane potential (delta psi) and the proton concentration gradient (delta pH) across the chromaffin granule membrane upon the rate and extent of catecholamine accumulation was studied in isolated bovine chromaffin granules. Freshly isolated chromaffin granules had an intragranular pH of 5.5 as measured by [14C]methylamine distribution. The addition of ATP to a suspension of granules resulted in the generation of a membrane potential, positive inside, as measured by [14C]thiocyanate (SCN-) distribution. The addition of carboxyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), a proton translocator, resulted in a reversal of the potential to negative values (measured by [3H]tetramethylphenylphosphonium (TPMP+)) approaching -90 mV. Changing the external pH of a granular suspension incubated with FCCP produced a linear perturbation in the measured potential from positive to negative values, which can be explained by the distribution of protons according to their electrochemical gradient. When ammonia (1 to 50 mM) was added to highly buffered suspensions of chromaffin granules there was a dose-dependent decrease in the transmembrane proton gradient (delta pH) and an increase in the membrane potential (delta...Continue Reading

Related Concepts

Adrenal Glands
Ammonium Sulfate
Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
Catecholamines
Bos indicus
Chromaffin Granule
Chromaffin System
Dihydroxyphenylalanine Hydrochloride, (2:1)
Medihaler-Epi
Intracellular Membranes

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.