Fat cells were disrupted in hypotonic medium and lipid micelles were collected by centrifugation. These lipid micelles contained lipase and triglyceride. Incubation of these lipid micelles with adrenaline resulted in marked lipolysis, but only a negligible lipolysis was observed in the absence of this hormone. The lipolytic activity of lipid micelles prepared from isolated fat cells which had been preincubated with 10μg/ml of adrenaline was higher than that of the micelles which preincubated without adrenline and was not stimulated by further addition of adrenaline to the assay system. Lipolysis in the lipid micelles was also increased by phospholipase C, theophylline or CaCl2 but not by phospholipase D.
On the other hand, no increase of protein kinase was observed during the incubation of the lipid micelles with the lipolytic agents such as adrenaline, phospholipase C, theophylline and CaCl2.
Based on these results, relationship between mechanism of adrenaline induced lipolysis and cyclic AMP was discussed.
