Cyclic AMP-dependent protein kinase activity and lipolysis in adipose tissue. Effect of fasting, oligomycin and iodoacetamide.

The release of glycerol into the medium, the concentration of cAMP, and the cAMP-dependent protein-kinase activity were studied in adipocytes and in fat-pads obtained from epididymal adipose tissue of rats under different conditions of feeding. An increase in the tissue concentration of cAMP and in the protein-kinase activity was observed in vivo at 48 and 96 h of fasting. A diminished release of glycerol was found in adipocytes from rats fasted for 48 h, in the absence of glucose, and the maximum concentration of cAMP was inferior to that of fed rats. Oligomycin and iodoacetamide, in the presence of epinephrine and glucose, produce a diminution in the values of the parameters studied. No significant differences were observed, however, in the responses of tissue obtained from fed and fasting rats to these compounds. The present results confirm previous observations and show the dependence of the lipolytic process on carbohydrate metabolism.