Influence of the hypothyroid state on lipolysis in human adipose tissue in vitro. Hypothyroid state and lipolysis.

. The regulation of lipolysis has been studied in subcutaneous adipose tissue removed under local anesthesia from hypothyroid patients. As control subjects were used hypothyroid subjects on replacement therapy. Noradrenaline induced no significant increase in lipolysis in tissue removed from hypothyroid patients, while the increase in glycerol release from adipose tissue of the control group was almost twofold. The addition of the alpha-adrenergic blocking agent phentholamine to noradrenaline-containing media produced a significant increase in the glycerol release from tissue of the hypothyroid patients as well as from the control subjects. Iso-propylnoradrenaline, a nearly selective beta-adrenergic agonist, theophylline or dibutyryl-cyclic AMP stimulated lipolysis in tissue from both groups. These results indicate that the lipase system cannot be the rate-limiting factor for the lipolytic response to noradrenaline in adipose tissue from hypothyroid patients. The decreased lipolytic response to noradrenaline in this tissue seems to be due to a more pronounced alpha-adrenergic effect of noradrenaline counteracting the lipolytic effect mediated by the beta-adrenergic receptor.