Hepatic uptake of glutamine and other amino acids during infection and inflammation

Catabolic illness such as sepsis and injury induce profound changes in host amino acid metabolism, including increased hepatic amino acid uptake. Because many amino acid-dependent pathways such as gluconeogenesis and acute-phase protein synthesis are activated in the liver during severe infection, this review will focus on the control of hepatic plasma membrane amino acid transport by specific inflammatory mediators. We specifically review the role of cytokines, eicosanoids, and glucorticoids in this response. Collectively, these signaling molecules act in a concerted manner to exert local control of hepatic function including the stimulation of amino acid transport. In particular, we review the role of glutamine and its transport in the liver, as it occupies a unique role in interorgan ammonia metabolism during critical illness.