In Vivo Hyperglycemic Effect of (−)- and (+)-Epinephrine in Dogs

(−)-Epinephrine is a major component in the regulation of the physiological homeostasis of glucose levels in the blood. (+)-Epinephrine, a synthetic stereoisomer, has been reported to have 10% of the in vitro adrenergic-lipolytic activity of (−)-epinephrine and only 7% in vitro competitive binding activity to fat cells. The in vivo hypergly-cemic effects of the two stereoisomers were studied in 6 dogs using a continuous glucose monitor. The method allowed a direct comparison between the hyperglycemic effects of the two stereoisomers in each dog in the course of each test; therefore, the effect of individual variability of response was eliminated. Previous reports on the relative activity of the two stereoisomers were carried out only in vitro. The previous methods required interassay comparison. The present method is in vivo and uses intra-assay comparison. The hyperglycemic activity of (+)-epinephrine bitartrate was found to have 12.8% of the hyperglycemic activity of its natural (−)-stereoisomer.