Fluorimetric Measurement of Exogenous and Endogenous Epinephrine and Norepinephrine in Peripheral Blood

Abstract

The reliability of the Weil-Malherbe and Bone method for the measurement of epinephrine and norepinephrine fluctuations in peripheral blood has been investigated. Epinephrine and norepinephrine injected intravenously (20 µg/kg) produced sharp elevations in appropriate blood levels but disappeared very rapidly, returning to the preinjection range in 2.5–5 minutes. No significant difference was observed in the disappearance rate of epinephrine as compared to norepinephrine. In one animal, evisceration and hepatectomy produced relatively little change in the disappearance pattern, suggesting that peripheral mechanisms, perhaps at adrenergic nerve endings or in skeletal muscle, are involved in removal of these hormones from the circulation. Added epinephrine does not disappear appreciably from plasma in whole blood maintained at body temperature in vitro in time periods comparable to these in the in vivo experiments. Stimulation of the splanchnic nerve in a dog and monkey produced readily detectable changes in both plasma epinephrine and norepinephrine levels with rather characteristic temporal patterns of response for each hormone. It is concluded that the Weil-Malherbe procedure is suitable for further application to investigations of sympathetic nervous system-adrenal medullary function.