PLASMA LIPOPROTEIN METABOLISM IN PERFUSED RAT LIVERS. I. PROTEIN SYNTHESIS AND ENTRY INTO THE PLASMA
The rates of synthesis of high density (D 1.063 to 1.21) and low density (D < 1.063) lipoproteins by the isolated perfused rat liver were compared in experiments in which uniformly labeled L-lysine-C/sup 14/ was added (by continuous injection) to the perfusing blood, When livers of rats fed a stock diet were perfused with blood from fasted rats, the specific activity of the protein of the D < 1.063 fraction was about four times that of the D 1.063 to 1.21 fraction, although the former contained somewhat less than half of the total radioactivity incorporated into lipoprotein protein because of its low concentration in rat plasma. The specific activity of albumin separated by starch block electrophoresis was less than that of either lipoprotein fraction. Neither previous whole-body irradiation nor Prefeeding the liver donor with a cholesterol-olive oil regimen caused any significant change in the rates of incorporation of lysine into the major lipoprotein classes, although these treatments markedly influenced cholesterologenesis. When normal livers were perfused with blood from cholesterol-fed rats, there was a twofold increase in the amount of D < 1.063 lipoprotein recovered and a corresponding increase in the incorporation of labeled amino acid into this material. When a D < 1.019 fraction was separated, it was found that this fraction had a specific activity greatly exceeding that of both the D 1.019 to 1.063 and D 1.063 to 1.21 lipoproteins. (auth)
- Research Organization:
- Yeshiva Univ., New York
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-16-014433
- OSTI ID:
- 4795213
- Journal Information:
- Journal of Clinical Investigation (U.S.), Journal Name: Journal of Clinical Investigation (U.S.) Vol. Vol: 41; ISSN JCINA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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