Clonidine-induced lipolysis in dog adipocytes by stimulation of histamine (H2)-receptors.

The effect of the alpha-adrenergic agonist clonidine on lipolysis was investigated in omental dog fat cells. In presence of theophylline, clonidine markedly enhanced lipolysis. This effect was competitively inhibited by the (H2)-receptor blocking agent cimetidine while the H1-histamine receptor antagonist (mepyramine) was without any significant effect. This result suggests that clonidine stimulates dog adipocyte lipolysis through histamine (H2)-receptor activation. Histamine and clonidine stimulated dog fat cell adenylate cyclase; the stimulation was suppressed by cimetidine.