How do catecholamines and cyclic AMP affect lipolysis in human subcutaneous and omental adipose tissue?
Catecholamine-induced lipolysis in human adipose tissue is mediated by beta-adrenergic receptors, inhibited by alpha receptors, and is lower in subcutaneous tissue likely due to lower cyclic AMP formation.
Abstract. The effects on lipolysis of l ‐noradrenaline, l ‐isopropylnoradrenaline, theophylline and N 6 ‐2′0‐dibutyryl‐adenosine 3,5 monophosphate have been studied on sections of human subcutaneous and omental adipose tissue obtained from 17 subjects undergoing abdominal surgery. In both tissues isopropylnoradrenaline, an almost pure beta adrenergic stimulator, induced higher glycerol release than noradrenaline. The alpha adrenergic blocking agent phentolamine increased the noradrenaline‐stimulated glycerol release in both tissues. These data indicate that catecholamine‐induced lipolysis is mediated by beta adrenergic receptors and is inhibited by alpha receptors. Lipolysis induced by either noradrenaline or isopropylnoradrenaline was greater in omental than in subcutaneous adipose tissue. On the other hand theophylline, which is supposed to increase the tissue level of cyclic AMP, and administration of cyclic AMP itself (the dibutyryl form), induced almost equal lipolysis in both tissues. It is therefore suggested that the lower lipolytic response to catecholamines of subcutaneous adipose tissue is due to a lower formation of cyclic AMP.
Suad Efendić (Mon,) studied this question.