Abstract
Mitochondrial ATPase activities of hepatoma BW7756 and ascites tumor cells. Influence of MG2+ ions, free fatty acids, and uncouplers.
Highlights
ATPase activity of mitochondria isolated from Ehrlich ascites carcinoma and hepatoma BW7756 declines over time when assayed in the absence of added magnesium ions
ATPase activity in mitochondria isolated from Ehrlich ascites carcinoma and hepatoma BW7756 cells is due to high levels of endogenous free fatty acids that are inhibiting adenine nucleotide translocation, while simultaneously inducing the loss of endogenous magnesium; and (b) that when tumor mitochondria are isolated and incubated in the presence of albumin the high levels of
We have investigated the action of albumin on uncoupler-stimulated ATPase activity in tumor mitochondria and present evidence suggesting that albumin is able to affect the magnitude of uncoupler-stimulation by increasing adenine nucleotide translocase activity and preventing the simultaneous loss of endogenous magnesium ions in the tumor mitochondria
Summary
ATP, phosphoenolpyruvate, cyanide phenylhydrazone, pyruvate kinase, m-chlorocarbonyl5-chloro-3-t-butyl-2’-chloro-l’-nitrosalicylanilide, oligomycin, atractyloside, and sodium dodecyl sulfate were obtained from Sigma Chemical Co., Saint Louis, MO. Pentex Fraction 5, was obtained from Miles Laboratories Inc. Research Products r4C]ATP, 42 pOi/pmol, was purchased from New England Nuclear. All spectrophotometric determinations were performed with a Perkin Elmer model 124 dual beam spectrophotometer. Magnesium analysis was performed using a Perkin Elmer model 303 absorption spectrophotometer. Radioactivity was measured using liquid scintillation counting with a Beckman model LS 255 scintillation counter, with an NIH mixture: toluene, Triton X-100, and H,O, 6:3:1 (v/v), respectively, with a final concentration of 4 g of 2,5-diphenyloxazole (PPO) and 50 mg of 1,4-bis[2-(5-phenyloxazolyl)]benzene (POPOP)/. Male Sprague-Dawley rats and female CD-l strain mice were obtained from Taconic Farms, Germantown, N. Y. C57LJ female mice were obtained from Jackson Laboratories, Bar Harbor, Maine, as was the hepatoma BW7756 cell line. Ehrlich Lettre cells were grown in female Ha/ICR or CD-l mice (or both) and maintained by.
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