Abstract
Summary
We have studied cellular cyclic AMP content and protein kinase activity in extracts of small and large adipocytes from two groups of rats differing in age and body weight. The data, expressed on a per cell basis, show that large adipocytes from larger rats present a significantly greater (p < 0.02) content of cyclic AMP and a 3-fold greater (p < 0.001) level of basal protein kinase activity than small adipocytes. Cyclic AMP (0.4 μM) stimulated the cyclic AMP-dependent protein kinase activity to a similar degree (about 3-fold) in both types of cells. No significant amount of cyclic GMP-dependent protein kinase activity was detected in extracts of adipocytes from either group of rats.
The increased cellular content of cyclic AMP and the elevated protein kinase activity in large adipocytes are probably responsible for the greater basal rate of lipolysis observed in these cells.
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