The effects of fasting on the thermogenic, lipolytic and cardiovascular responses to adrenaline were examined in nine normal, young, non-obese subjects. Each subject attended for study after 12, 36 and 72 h fasting. After basal measurements adrenaline was infused at 25 ng/min per kg ideal body weight for 90 min. Fasting increased the thermogenic effect of the adrenaline (mean 14·6 (SE 1·7), 16·6 (SE 1·8), 22·6 (SE 1·6) J/:min per kg fat-free mass after 12, 36 and 72 h fasting respectively; P < 0·001, ANOVA). Basal plasma palmitate turnover increased with duration of fasting (1·48 (SE 0·22), 1·95 (SE 0·34) and 2·26 (SE 0·33) μmol/min per kg body weight: P < 0·001, ANOVA), but the response to adrenaline was unaffected by fasting. The percentage values for basal plasma palmitate turnover oxidized were 44 (SE 2; 12 h), 46 (SE 5; 36 h) and 42 (SE 4)% (72 h). In response to adrenaline this percentage fell, suggesting that adrenaline infusion may favour intra-tissue lipid oxidation.
