Synergic effect of insulin and prostaglandin E1 on stimulated lipolysis

1. The inhibitory effect of prostaglandin E1 on free fatty acid release from adipose tissue is significantly greater when the lipolysis is stimulated by 1-methyl-3-isobutyl xanthine than when stimulated by adrenaline. 2. The antilipolytic effect of insulin on adrenaline and 1-methyl-3-isobutyl xanthine stimulated lipolysis, is suppressed in the presence of inhibitors of prostaglandin synthetase i.e. indomethacin or phenelzine. 3. In the presence of phenelzine, the lack of effect of insulin on adrenaline and 1-methyl-3-isobutyl xanthine lipolysis is overcome by a small amount of prostaglandin E1 (10(-10)M) but not of prostaglandin F2 alpha. 4. The addition of prostaglandin E1 (10(-10)M) restores the inhibitory effect of insulin on cyclic AMP accumulation.