Depression of cytidine 3':5'-cyclic monophosphate phosphodiesterase activity in developing tissues of guinea pigs.

Abstract
Changes in levels of the newly discovered cytidine 3'':5''-cyclic monophosphate (cCMP) phosphodiesterase in some representative tissues (cerebral cortex, kidney, intestine, liver, heart and lung) of guinea pigs from various developmental stages (fetus, neonate, pup and adult) were studied and compared with those of cAMP and cGMP phosphodiesterases in the same tissues. The tissue levels of cCMP phosphodiesterase were invariably the lowest in every one of the fetal tissues examined, the highest in The corresponding tissues from the pups and adult, with intermediate levels seen in some neonatal tissues. The patterns of the ontogenetic changes in levels of cAMP and cGMP phosphodiesterase activities, however, were variable and tisse specific. The depressed cCMP phosphodiesterase activity (hence, the elevated cCMP concentration) is perhaps a common factor in developing tissues undergoing rapid cell proliferation. Metabolism of cCMP is perhaps more closely related to cell proliferation than the metabolism of cAMP or cGMP.