LIPOLYTIC RESPONSIVENESS TO EPINEPHRINE IN NONDIABETIC AND DIABETIC HUMANS

To determine whether the sensitivity of adipose tissue lipolysis to ca techolamines is increased in poorly controlled insulin-dependent diabe tes, the lipolytic response to epinephrine was measured in seven nondi abetic volunteers and seven poorly controlled diabetic subjects with u se of[1-C-14]palmitate as a tracer. Subjects received sequential l-h i nfusions of epinephrine, which produced epinephrine concentrations of similar to 1,000, similar to 1,750, similar to 3,500, and similar to 6 ,000 pmol/l. A pancreatic clamp was used to maintain constant plasma h ormone levels. Concentration-response curves were constructed for each subject from the integrated lipolytic response during each epinephrin e infusion. There was no difference in maximal lipolytic response (117 +/- 19 vs. 152 +/- 11 mu mol.kg(-1).h(-1)) or in maximally effective (3,171 +/- 267 vs. 3,357 +/- 349 pmol/l) or half-maximally effective ( 1,081 +/- 109 vs. 1,015 +/- 120 pmol/l) epinephrine concentrations bet ween nondiabetic and diabetic subjects, respectively (all P = NS). In control subjects, maximum beta-hydroxybutyrate concentrations were ach ieved at lower epinephrine concentrations than those required for a ma ximum lipolytic effect. Thus, under pancreatic clamp conditions, the l ipolytic response to epinephrine in nondiabetic and diabetic subjects was similar.