Peripheral blood epinephrine levels in dogs during intravenous infusion.

Femoral arterial and venous blood epinephrine levels were followed in dogs during the infusion of l-epinephrine at rates of 1.25–10 µg (as the base)/kg/min. for periods of 37–197 minutes. The epinephrine concentration in arterial blood rose from control values of less than 1 µg/l., the lowest concentration that could be estimated, to levels of 8.5, 19, 75 and 201 µg/l. at infusion rates of 1.25, 2.5, 5 and 10 µg/kg/min., respectively. For these same infusion rates, the simultaneously determined venous blood levels were 7.8, 10, 27 and 70 µg/l., respectively. By extrapolation, these data show that at an infusion rate of 3.4 µg/kg/min., the lowest rate known to produce shock in dogs, the arterial blood level was 39 µg/l. This is approximately twice the maximum concentration of 20.6 µg/l. of endogenously released epinephrine observed during hemorrhagic shock in dogs.