The present investigation was aimed at studying the acute effects of an adrenaline infusion on the exchange of free fatty acids in the leg and splanchnic bed. Seven healthy males participated in the study. Adrenaline (40 ng/(min X kg body weight)) (0.22 nmol/(min X kg body weight] was infused to produce a plasma concentration similar to that seen in connection with surgery (2.77 +/- 0.42 nmol/l). Leg and splanchnic blood flow were measured and the femoral and hepatic arterio-venous differences for the total fraction of FFA were determined. 1-14C-oleic acid was infused intravenously so as to determine uptake and release of FFA. Measurements were made before and between 30 and 40 min after the start of the adrenaline infusion. The FFA concentration rose by 140% and the FFA uptake in the leg and splanchnic region increased about three fold. For 3-hydroxybutyrate the arterial concentrations as well as leg uptake and splanchnic uptake increased about six fold, four fold and eight fold, respectively. Ketogenesis accounted for a large part of the FFA uptake in the splanchnic bed during adrenaline infusion. We conclude that adrenaline infusion results in pronounced changes in FFA and 3-hydroxybutyrate concentrations and in the exchange of these substrates in leg and splanchnic bed. The adrenaline-induced increases in FFA and 3-hydroxybutyrate metabolism were generally more marked than those seen during and immediately after surgery.