Catecholamines and Metabolism of Human Adipose Tissue

Abstract Lipolysis in human omental tissue incubated in glucose‐containing medium was determined by measuring glycerol release in the presence of different concentrations of noradrenaline and adrenaline. Almost identical responses were obtained with the two catecholamines: significant increases in the glycerol release were obtained when they were added at concentrations as small as 0.03 × 10 −5 M , and maximal lipolysis was produced at 0.3–3 × 10 −5 M . Noradrenaline as well as 10 −2 M of theophylline‐induced increases in the glycerol release were well correlated with the basal glycerol release. Maximal glycerol release obtained with theophylline (10 −2 M ) was almost constantly six to eight times the basal glycerol release, whereas the lipolytic effect of noradrenaline was more variable and in no experiments exceeded significantly the theophylline effect. The results indicate that the formation of cyclic adenosine‐3′,5′‐monophosphate (3′,5′‐AMP) or some process between the adrenergic receptor and the adenyl cyclase system is rate‐limiting for the lipolytic response to noradrenaline. The data also suggest that variations in the lipolytic response to noradrenaline of adipose tissue removed from different subjects are principally caused by variations in the effect of noradrenaline on the formation of 3′,5′‐AMP. The present material of 32 patients does not allow critical analysis of the possible influence of sex, age and bodyweight of the donors on the tissue response to noradrenaline. However, the data indicate that adipose tissue obtained from old subjects has less lipolytic response than such tissue from young subjects.