Journal of Lipid Research, Vol 21, 443-448, Copyright © 1980 by Lipid Research, Inc.
Influence of adipocyte isolation by collagenase on phosphodiesterase activity and lipolysis in man
P Engfeldt, P Arner and J Ostman
The maximum phosphodiesterase activity (Vmax) with low and high Km was,
respectively, 10- and 3-times greater in tissue fragments than in
collagenase-isolated adipocytes obtained from subcutaneous fat layers in
man. The exposure of such tissue fragments to collagenase of various
origins in order to isolate the fat cells resulted in a 60-70% inhibition
of phosphodiesterase (PDE) activity. Noradrenaline- and isopropyl
noradrenaline-induced rates of lipolysis were more rapid in the isolated
fat cells than in the tissue fragments. The sensitivity to catecholamines,
however, was the same for the two tissue preparations. Nor did they differ
in respect to the effect of theophylline, a PDE inhibitor, on the rate of
lipolysis. The time curve for cyclic AMP accumulation was significantly
higher in the isolated adipocytes than in tissue fragments in the presence
of isopropyl noradrenaline. It is concluded that the greater lipolytic
response of collagenase-isolated adipocytes than of tissue fragments to
catecholamines may be attributed, at least in some measure, to the higher
concentration of cyclic AMP resulting from a decrease in PDE activity.
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