Cyclic 3',5'-adenosine monophosphate phosphodiesterase in the thymus of normal and leukemic mice

Changes in the cyclic AMP phosphodiesterase of the thymus were observed during leukemogenesis in the AKR mouse. Upon maturation, activity at 1.0 muM and 100 muM cyclic AMP concentrations decreased in both the AKR mouse and normal Swiss mice. The thymus of the leukemic mouse had sharply higher phosphodiesterase activity. Much of the phosphodiesterase activity of normal and leukemic mice was associated with particulate fractions, and, as indicated by marker enzymes for particulate components, the high affinity phosphodiesterase was enriched in a fraction containing plasma membranes.