New evidence for compartmentalization of ovarian 3',5'-cyclic AMP-dependent protein kinase activity.

The present experiments were designed to study whether cAMP-dependent protein kinase (CDPK) activity is functionally compartmentalized within the ovary. Pseudopregnant rats received two identical injections of highly purified hCG or LH 30 min apart. The time of the second injected coincided with peak in vivo dissociation of ovarian CDPK holoenzyme activity as a result of the first hormonal injection. After either 2 μg hCG or 5 IU hLH injections, intracellular ovarian levels of cAMP increased with concomitant decrease in CDPK holoenzyme activity. However, when animals received a second hormonal injection 30 min later, the second injection failed to enhance intracellular cAMP concentrations, but did sustain suppressed CDPK holoenzyme activity so that a return toward basal CDPK holoenzyme activity was delayed an additional 60 min. When 1 IU LH or .05 μg hCG was given, CDPK holoenzyme activity decreased after the initial injection and returned toward basal levels with a single injection, but the decreased CDP...