Interleukin-1 and tumor necrosis factor alter plasma concentration and interorgan fluxes of taurine in dogs.

We examined the effects of interleukin-1 beta (IL-1), tumor necrosis factor (TNF), and alanylglutamine (Ala-Gln) infusion on the plasma concentrations and interorgan fluxes of taurine and taurine precursors, including methionine and serine, using chronically catheterized awake dogs. In the first study, the dogs received 5 micrograms/kg/h of either human recombinant IL-1 or TNF intravenously for 2 h. Taurine fluxes in the liver and gut were calculated by blood flows and arteriovenous differences during infusion and for 2 h after discontinuation of the cytokine infusions. The 2 h continuous infusions of TNF and IL-1 resulted in 60 and 90% increases, respectively, in the arterial plasma taurine concentration. Hepatic taurine flux changed from uptake to release after 2 h of continuous IL-1 infusion. In the second study, we investigated whether Ala-Gln infusion affects taurine metabolism under normal and stress conditions. The dogs were given a constant 2 h intravenous infusion of IL-1 or saline. Ala-Gln (6 mumol/kg/min) was infused simultaneously during the second hour. Plasma concentrations and fluxes, across the liver, gut, and lung, of taurine and taurine precursors were studied. IL-1 administration increased the plasma concentration, hepatic release, and lung uptake of taurine. Ala-Gln infusion did not affect either plasma concentrations or organ fluxes of taurine. These data suggest that cytokines play a role in taurine metabolism under stress conditions.