Abstract
The effects of pantethine on cholesterol and fatty acid metabolism were investigated in isolated rat hepatocytes. Preincubation of the cells with pantethine induced a concentration-dependent decrease of the radioactivity incorporated into carbon dioxide and lipids in incubations with [2-14C]acetate. When pantethine and the labeled substrate were simultaneously added to the cell suspension, there was an enhancement of carbon dioxide radioactivity at short incubation time (5 min) whereas, at longer incubation time, values were comparable to those of controls; lipid radioactivity, instead, was dramatically reduced by pantethine even at short incubation time and decreased further during the incubation, being 23% of that of controls at 60 min. Analysis of the incubation medium showed that pantethine induced a concentration- and time-dependent release of acetate into the medium. Results of the effect of the acetate concentration on the incorporation of [2-14C]acetate radioactivity into CO2 and lipids in control hepatocytes allowed the conclusion that the above-described modifications induced by pantethine are only partially attributable to the dilution of the labeled substrate, and that catabolism of acetate to carbon dioxide is stimulated by the disulphide pantethine, whereas cholesterol and fatty acid syntheses are inhibited.
Highlights
The effects of pantethine on cholesterol and fatty acid metabolism were investigated in isolated rat hepatocytes
Results of the effect of the acetate concentration on the incorporation of [ 2-I4C]acetate radioactivity into CO2 and lipids in control hepatocytes allowed the conclusion that the above-described modifications induced by pantethine are only partially attributable to the dilution of the labeled substrate, and that catabolism of acetate to carbon dioxide is stimulated by the disulphide pantethine, whereas cholesterol and fatty acid syntheses are inhibited.-Cighetti, G., M
The results are reported in Fig. 4; at short incubation time, COzradioactivity was higher with pantethine, even if not significantly, than in its absence, whereas the contrary was observed for lipids
Summary
Materials [2-I4C]Acetate (55-58 mCi/mmol), [1-"Clpalmitate (58 mCi/mmol), [l-'4C]stearic acid (55 mCi/mmol), and [2-'4C]cholesterol (56 mCi/mmol) were supplied by Amersham International (Amersham, Bucks, U.K.). The incubations were started by the addition of the labeled precursor and were carried out at 37OC in a Dubnoff incubator in stoppered polycarbonate flasks containing the hepatocyte suspension (0.9-1.2 x lo cells, 3 ml final volume). For the determination of radioactivity associated with COn, the filter paper was transferred from the center well of the incubation flask to the counting vial with methanol (1 ml). The livers obtained from three Sprague-Dawley male rats were homogenized (1:2, W/V)in the incubation buffer described above. Aliquots of the homogenate (0.5 ml, 20 mg of protein) were incubated for various times with [2-'4C]acetate (1.5 x lo dpm; 22 pM) in the presence of 1 mM pantethine or in its absence (controls); final volume was 0.62 ml.
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