Interrelated calcium ion and cyclic AMP inhibition of placental lactogen secretion by cultured human term trophoblast.
Calcium ion has been shown to have a negative regulatory effect on the secretion of human placental lactogen (hPL). We report an inhibitory effect of cyclic AMP on hPL secretion in a model system of cultured human term trophoblast. Similar results were obtained by modulation of cyclic AMP-phosphodiesterase. The effects of ionophore A23187 and cyclic AMP were non-additive. In searching for the sequence of the common pathway, we found that the ionophore A23187 reduced cyclic AMP concentration and that the inhibitory effect of cyclic AMP was abolished by verapamil, a calcium channel blocker, and by trifluoperazine, a calcium-calmodulin inhibitor. Cyclic AMP seems to mobilize intracellular calcium, and the latter, by way of a calcium-calmodulin complex, modulates the secretion of hPL.
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007473:Ion Channels; D010928:Placental Lactogen / Q000378:metabolism*; D011247:Pregnancy; D014268:Trifluoperazine / Q000494:pharmacology; D014327:Trophoblasts / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D007473:Ion Channels; D014268:Trifluoperazine; D000001:Calcimycin; D003994:Bucladesine; D010928:Placental Lactogen; D014700:Verapamil; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D002118:Calcium