Antilipolytic effect of adenosine in isolated perifused fat cells

Adenosine markedly inhibits cyclic AMP accumulation in isolated fat cells, whereas inhibitory effects of adenosine on lipopolysis have been difficult to demonstrate. The present study has been performed on isolated "perifused" fat cells where continuous monitoring of the lipolytic rate is possible and where modulating substances, such as adenosine, are not allowed to accumulate. Adenosine deaminase was ineffective as a lipolytic agent in perifused fat cells, suggesting no important background activity of adenosine in this system. Micromolar concentrations of adenosine inhibited lipolysis induced by noradrenaline (0.3--1 micrometer) and theophylline (1 mM). Theophylline was an effective lipolytic agent also in perifused fat cells suggesting that antagonism of adenosine is not the major mode of action of this drug on fat cells.