The ascorbate-driven reduction of extracellular ascorbate free radical by the erythrocyte is an electrogenic process.
Erythrocytes can reduce extracellular ascorbate free radicals by a plasma membrane redox system using intracellular ascorbate as an electron donor. In order to test whether the redox system has electrogenic properties, we studied the effect of ascorbate free radical reduction on the membrane potential of the cells using the fluorescent dye 3,3'-dipropylthiadicarbocyanine iodide. It was found that the erythrocyte membrane depolarized when ascorbate free radicals were reduced. Also, the activity of the redox system proved to be susceptible to changes in the membrane potential. Hyperpolarized cells could reduce ascorbate free radical at a higher rate than depolarized cells. These results show that the ascorbate-driven reduction of extracellular ascorbate free radicals is an electrogenic process, indicating that vectorial electron transport is involved in the reduction of extracellular ascorbate free radical.
Department of Molecular Cell Biology, Sylvius Laboratory, Leiden University Medical Center, P.O. Box 9503, 2300 RA, Leiden, The Netherlands
M M
MM
VanDuijn
J
J
Van der Zee
P J
PJ
Van den Broek
D001205:Ascorbic Acid / Q000378:metabolism*; D052160:Benzothiazoles; D002232:Carbocyanines; D002462:Cell Membrane / Q000502:physiology; D004912:Erythrocytes / Q000378:metabolism / Q000502:physiology*; D005456:Fluorescent Dyes; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008564:Membrane Potentials; D010084:Oxidation-Reduction
D052160:Benzothiazoles; D002232:Carbocyanines; D005456:Fluorescent Dyes; D005609:Free Radicals; C012944:3,3'-dipropyl-2,2'-thiadicarbocyanine; D001205:Ascorbic Acid