Patterns of cyclic AMP phosphodiesterases during rat testis development

Summary Cyclic AMP phosphodiesterase (PDE; E.C.: 3.1.4.17) plays a crucial role in the regulation of intracellular cAMP levels arising from the hormonal activation of membrane-bound adenylcyclase in the target cell. In the present study, we revealed a complex sequence of appearance and disappearance of individual molecular electrophoretic forms of PDE during the development of the rat testis. Kinetic analysis of cAMP hydrolysis in crude testis homogenates of developmental stages where multiple PDE isozymes are expressed revealed complex kinetic behavior of PDE. After separation of individual isozymes by elution from starch gel blocks, several enzymatic forms still act with complex kinetics, indicating negatively cooperative behavior. The stage specificity of the kinetic properties of PDE appears to be related to the hormonally regulated events leading to the initiation of male puberty.