Transmembrane ferricyanide reductase activity in Ehrlich ascites tumor cells.
A transmembrane ferricyanide reductase activity was assayed in intact Ehrlich ascites tumor cells. Kinetic measurements gave a Km of 0.14 mM and a Vmax of 0.31 mumol/min per 10(6) cells. In short-term batch experiments, this activity was enhanced in the presence of 10 mM lactate, a source of cytosolic NADH. The transmembrane redox activity was accompanied by alkalinization of the cytosol. Both ferricyanide reduction and proton extrusion were diminished in the presence of 0.2 mM amiloride. Several cytotoxic drugs significantly inhibited the ferricyanide reductase activity at concentrations at which they show antineoplastic activity.
Medina
M A
MA
Laboratorio de Bioquímica, Facultad de Ciencias, Universidad de Málaga, Spain.
Sánchez-Jiménez
F
F
Segura
J A
JA
Núñez de Castro
I
I
D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology*; D002460:Cell Line; D005260:Female; D005947:Glucose / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008566:Membranes / Q000201:enzymology; D051379:Mice; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010084:Oxidation-Reduction
D007773:Lactates; D009243:NAD; D019344:Lactic Acid; D009247:NADH, NADPH Oxidoreductases; C014227:ferricyanide reductase; D005947:Glucose