The purpose of this study was to determine the effect of epinephrine on net lactate (La) uptake at constant elevated blood La concentration and steady level metabolic rate (O₂ uptake) in the canine gastrocnemius-plantaris muscle in situ. Infusion of La/lactic acid (pH 3.5) established a mean arterial blood La concentration of ~10 mM while normal blood-gas and pH status were maintained as the gastrocnemius-plantaris was stimulated with tetanic trains at a rate of one contraction every 4 s. After steady-state control measures, epinephrine was infused for 35 min at rates that produced a high physiological concentration with (Pro; n = 6) and without (Epi; n = 6) -adrenergic-receptor blockade via propranolol. Net La uptake values during the control conditions were not significantly different between trials (Epi: 0.756 ± 0.043; Pro: 0.703 ± 0.061 mmol · kg¹ · min¹). Steady level O₂ uptake averaged ~69.5 ml · kg¹ · min¹ for both control conditions and did not significantly change over the course of the experiments in either set of trials. Epi experiments resulted in a significantly reduced net La uptake (0.346 ± 0.088 mmol · kg¹ · min¹ after 5 min of infusion) compared with control value at all sample times measured. However, net La uptake was not significantly different from control at any time during Pro (0.609 ± 0.052 mmol · kg¹ · min¹ after 5 min of infusion). When the change from the respective control values for net La uptake was compared across time for both series of experiments, Epi resulted in a significantly greater change from control than did Pro. This study suggests that epinephrine can have a profound effect on net La uptake by contracting muscle and that these effects are elicited through -adrenergic-receptor stimulation.