Isolated perfused rat liver experiments were performed in which normal livers and livers from Walker 256 tumor-bearing rats were perfused with normal blood or blood from tumor-bearing rats. The serum protein synthetic activity of the perfused livers was determined by following the incorporation of l-lysine-6-14C into total serum protein and the albumin and α- and β-globulin fractions of the perfusing blood. Radioactivity of the protein samples was determined by combustion to CO2, absorption in an ethanolamine-ethylene glycol monomethyl ether solution, followed by liquid scintillation counting.

Results indicate that blood from tumor-bearing rats carries an inhibitory signal which causes a decrease in the serum protein synthetic activity of the perfused liver. Thus normal livers perfused with blood from tumor-bearing rats have a lower serum protein synthetic activity than normal livers perfused with normal blood. In the same way, livers from tumor-bearing rats perfused with blood from tumor-bearing rats have a lower serum protein synthetic activity than livers from tumor-bearing rats perfused with normal blood. Also, livers from tumor-bearing rats perfused with normal blood were found to have a higher serum protein synthetic activity than livers from normal rats perfused with normal blood.

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This work was supported in part by USPHS Grant CA-04236-08 from the National Cancer Institute and National Science Foundation Grant GB-6504 from the Physiological Processes Section.

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©1969 American Association for Cancer Research.
1969
Cancer Research, Inc.