Independent and combined actions of interleukin-1β, tumor necrosis factor α, and glucagon on amino acid metabolism in the isolated perfused rat liver

Abstract Conflicting reports concerning the hepatic effects of interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) in the metabolic response to injury led us to investigate the influence of physiological concentrations of these cytokines on amino acid metabolism in the isolated perfused rat liver. IL-1β was ineffective at a concentration of 1 ng/mL, whereas TNFα (0.7 ng/mL) reduced the uptake of some of the main gluconeogenic amino acids (alanine, −55.3 ± 4.9 v −72.9 ± 13.7 nmol·min −1 ·g −1 in controls, P v −9.9 ± 6.7 nmol·min −1 ·g −1 in controls, P