This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Toporek, M. Search for Related Content PubMed PubMed Citation Articles by Toporek, M.

Effect of Albumin Fraction from Blood of Tumor-bearing Rats on Serum Protein Production by Isolated Perfused Normal Rat Livers¹

Department of Biochemistry, Thomas Jefferson University, Jefferson Medical College, Philadelphia, Pennsylvania 19107

It was previously postulated that whole blood from Walker 256 tumor-bearing rats carries a signal factor(s) which decreases the serum protein-synthetic activity of perfused normal rat livers. Preliminary isolated perfused normal rat liver experiments with albumin and -, ß-, and -globulin fractions, separated from blood of tumor-bearing rats on DEAE-Sephadex A-50 columns, indicated signal factor activity in the albumin fractions only. Further experiments were performed with albumin fractions obtained from large pools of blood from normal and tumor-bearing rats. Serum protein production was followed by: (a) determination of the incorporation of L-lysine-6-¹⁴C into total serum protein, which was precipitated with trichloroacetic acid; (b) oxidation of the dried protein to ¹⁴CO₂ by the Schöniger method; (c) absorption of the ¹⁴CO₂ in an ethanolamine-ethylene glycol monomethyl ether solution; (d) liquid scintillation counting.

From the results obtained, it is concluded that the signal factor activity in whole blood from Walker tumor-bearing rats is located in the broad albumin fraction of such blood, as fractionated on DEAE-Sephadex A-50. On the basis of the method of preparation, it is speculated that the signal factor substance(s) is a large molecule, possibly protein, or a smaller molecule tightly bound by a nondialyzable molecule. The addition of albumin fractions from normal blood to the perfusion media, whole blood or synthetic substitutes, had no significant effect on the protein-synthetic activity of the perfused rat liver under the conditions used.

¹ This work was supported in part by National Science Foundation Grants GB-12436 and GB-23914 from the Physiological Processes Section.

Received 3/ 2/71. Accepted 8/12/71.