Evidence for activation of an active electrogenic proton pump in Ehrlich ascites tumor cells during glycolysis

Journal Article · Thu Jan 01 00:00:00 EST 1981 · J. Membr. Biol.; (United States)

DOI:https://doi.org/10.1007/BF01870520· OSTI ID:5406560

Heinz, A; Sachs, G; Schafer, J A

The addition of glucose to a suspension of Ehrlich ascites tumor cells results in rapid acidification of the extracellular medium due to lactic acid production. The nature of the H+ efflux mechanism has been studied by measuring the time course of the acidification, the rate of proton efflux, the direction and relative magnitude of the H+ concentration gradient, and the voltage across the membrane. Using the pH-sensitive dye acridine orange, we have established that after addition of 10 mM glucose an outward-directed H+ concentration gradient develops. As the rate of glycolysis slows, the continued extrusion of H+ reverses the direction of the H+ concentration gradient. Changes in absorbance of the voltage-sensitive dye diethyloxadicarbocyanine iodide (DOCC), and changes in the distribution of the lipid permeant cation tetraphenyl phosphonium, showed a dramatic and persistent hyperpolarization of the membrane voltage after glucose addition. The hyperpolarization was prevented by the protonophore tetrachlorosalicylanalide (TCS) and by valinomycin, but not by the neutral-exchange ionophore nigericin. Inhibitors of lactate efflux were found to reduce the rate of acidification after glucose addition but they had no effect on the magnitude of the resulting hyperpolarization. On the basis of these and other data we suggest that an active electrogenic pump mechanism for H+ efflux may be activated by glucose and that this mechanism operates independently of the lactate carrier system.

• OSTI ID: 5406560
• Journal Information: J. Membr. Biol.; (United States), Vol. 61:3
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ASCITES TUMOR CELLS
DYNAMIC FUNCTION STUDIES
CELL MEMBRANES
PERMEABILITY
ACIDIFICATION
ACRIDINE ORANGE
BIOLOGICAL PATHWAYS
EHRLICH ASCITES TUMOR
GLUCOSE
HYDROGEN IONS
LACTIC ACID
PH VALUE
ACRIDINES
ALDEHYDES
AMINES
ANIMAL CELLS
AZINES
CARBOHYDRATES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHARGED PARTICLES
DYES
EXPERIMENTAL NEOPLASMS
HETEROCYCLIC COMPOUNDS
HEXOSES
HYDROXY ACIDS
IONS
MEMBRANES
MONOSACCHARIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
SACCHARIDES
TUMOR CELLS
550300* - Cytology
550200 - Biochemistry