BIOSYNTHESIS OF PROGESTERONE IN VITRO IN CORPUS LUTEUM OF PSEUDO-PREGNANT RATS - INFLUENCE OF CA2+ AND MG2+ ON STIMULATORY EFFECTS OF LUTEINIZING HORMONE AND A HIGH CONCENTRATION OF K+ OR CYCLIC 3',5'-ADENOSINE MONOPHOSPHATE

1. 1. Ovine luteinizing hormone (LH), as well as cyclic 3′,5′-adenosine monophosphate (cyclic AMP), stimulates in vitro the biosynthesis of progesterone in the corpus luteum of pseudo-pregnant rats. Numerous results indicate that cyclic AMP could mediate the action of LH. 2. 2. Increasing the concentration of K+ in the external medium and removing an equivalent amount of Na+, leads to the stimulation of progesterone biosynthesis as does the presence of LH; the two effects are additive. The possibility of cyclic AMP being an intermediate of both actions is discussed. 3. 3. The presence of Ca2+ is required in the external medium in order to make the appropriate stimulus for the biosynthesis of progesterone effective. This cation seems to be necessary for the steps following production of cyclic AMP. 4. 4. The function of Mg2+ is less well established than is that of Ca2+ because of difficulties in chelating this cation specifically. It may play a part in the process of cyclic AMP formation. © 1969.