Filter trapping of 14CO2: a simple and quantitative method for studying cell metabolism in hepatocyte monolayers

Relationship of the uptake and beta-oxidation of 18-carbon fatty acids with stimulation of murine mammary tumor cell growth

The effects of stearic (18:0), oleic (18:1) and linoleic (18:2) acid on the in vitro growth of murine mammary tumor cell line 4526 were compared to 4526 uptake and beta-oxidation of those fatty acids. Both 18:1 and 18:2 stimulated, while 18:0 inhibited growth. Likewise, uptake and oxidation rates were much lower for 18:0 than for 18:1 and 18:2. The influence of glucose, insulin and fatty acid-depletion on 4526 fatty acid incorporation and oxidation was also determined. The correlation between effects on in vitro growth and ability to assimilate 18:0, 18:1 and 18:2 may partially explain the stimulation by unsaturated and inhibition by saturated fatty acids of in vivo 4526 tumorigenesis.

Altered thiol group status in the heart ornithine decarboxylase inactivated following perfusion with t-butylhydroperoxide

1. The perfusion for 15 min of isolated rat hearts with 100 microM t-butylhydroperoxide leads to a 75% diminuition of the tissue GSH/GSSG ratio. 2. After t-butylhydroperoxide infusion, the isoproterenol-stimulated heart ODC was strongly inhibited. The addition of 2 mM DTT in the assaying buffer removed the ODC inactivation. 3. The inhibited ODC had an eluition profile similar to active ODC when chromatographed on a Sephacryl S-200 column; moreover, the ODC activity recovered after a thiol affinity chromatography as unbound fraction, was two times increased in the t-butylhydroperoxide perfused hearts in comparison to control. 4. The hearts perfused with 1 mM acetylcysteine after 15 min of perfusion with t-butylhydroperoxide recovered almost completely the initial ODC activity.