Effects of Hypophysectomy of Liver Donor on Net Synthesis of Specific Plasma Proteins by the Isolated Perfused Rat Liver: MODULATION OF SYNTHESIS OF ALBUMIN, FIBRINOGEN, α1-ACID GLYCOPROTEIN, α2-(ACUTE PHASE)-GLOBULIN, AND HAPTOGLOBIN BY INSULIN, CORTISOL, TRIIODOTHYRONINE, AND GROWTH HORMONE

Abstract

Abstract The isolated rat liver perfused for 12 or 24 hours has been used to study effects of total hypophysectomy of the liver donor, and of added cortisol, bovine growth hormone, insulin, and triiodothyronine on the net biosynthesis of five specific plasma proteins, namely, rat serum albumin, fibrinogen, α1-acid glycoprotein, α2-(acute phase) globulin, and haptoglobin. With all four hormonal supplements livers from fed hypophysectomized rats perfused at pH 7.10 synthesized about 50% as much albumin as livers from normal donors. Similarly with a supplement including all four hormones, synthesis of fibrinogen, α1-acid glycoprotein, and haptoglobin was close to that observed in normals. Elimination of either growth hormone, insulin or triiodothyronine, had effects which varied depending on the hormone deleted and the specific plasma protein in question. Fibrinogen synthesis in the absence of triiodothyronine was not different from that with the four hormones; however, deletion of either the supplement of insulin or growth hormone resulted in a small but significant decrease in net synthesis below that seen with the four hormones. Deletion of either triiodothyronine, growth hormone, or insulin was associated with failure to increase synthesis of haptoglobin above that seen in the absence of all hormones at 12 hours, and at 24 hours was only 50% of that with supplementation by all four hormones. In the absence of hormone supplements synthesis of α2-(acute phase) globulin by livers from hypophysectomized donors was undetectable. With all four hormones synthesis of this protein was not significantly different from that by livers of normal donors. Omission of either triiodothyronine, insulin, or growth hormone diminished the net synthesis of the protein in a manner closely similar to that observed with haptoglobin. Of the four hormones, omission of insulin or growth hormone was reflected in a small but significant decrease in net uptake of free amino acid nitrogen. Strongly positive nitrogen balance for the perfusion system was referable mainly to normal amino acid uptake concomitant with significantly decreased urea production and to the presence of insulin. Absence of insulin (even in the presence of growth hormone, triiodothyronine, and cortisol) was associated with increased urea production, negative nitrogen balance, and reduced incorporation of l-[1-14C]lysine into hepatic protien.