title: Characterization of the synthesis and release of human placental lactogen and human chorionic gonadotropin by an enriched population of dispersed placental cells.
abstract: An enriched fraction of human placental cells that synthesize and release both placental lactogen (hPL) and hCG was obtained by isopycnic centrifugation of collagenase/hyaluronidase-dispersed cells through a density gradient of 40% Percoll. The enriched cells, which banded at a density of approximately 1.01 g/ml, comprised 10-15% of the total DNA. During the first 24 h after attachment, the cells released 50-250 ng hPL and 4-10 mIU hCG/10(6) cells. Thereafter, the rate of hPL release decreased, while the rate of hCG and [35S]trichloroacetic acid-precipitable protein release remained constant. The enriched cells responded to phospholipase A2, low extracellular calcium, and (Bu)2cAMP in a manner similar to that of placental explants. Phospholipase A2 (0.1 and 1 U/ml) stimulated hPL release by 270% and 568%, respectively, and low extracellular calcium (0-0.18 mM) stimulated hPL release by 48%. (Bu)2 cAMP (1 mM) stimulated hCG release by 42%, but had no effect on hPL. Estradiol (10(-5)-10(-12) M) and progesterone (10(-5)-10(-10) M) had no effect on the synthesis and release of either hPL or hCG over a 6-day period. In addition, insulin (8.3 X 10(-7) M) and changes in medium glucose content (0-5 mg/ml) had no effect on hPL release over a 72-h period. Since the enriched trophoblast cells respond to provocative stimuli in a manner similar to that of explants and placental fragments, this cell population is a useful model system for investigations of the cellular mechanisms of hPL and hCG release.
mesh_terms: D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D005260:Female; D006801:Humans; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010920:Placenta / Q000378:metabolism*; D010928:Placental Lactogen / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D006063:Chorionic Gonadotropin; D003994:Bucladesine; D010928:Placental Lactogen; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium