title: Ca2+ entry through L-type voltage-sensitive Ca2+ channels stimulates the release of human chorionic gonadotrophin and placental lactogen by placental explants.
abstract: The release of human chorionic gonadotrophin (hCG) and placental lactogen (hPL) by human placental explants can be stimulated by Ca2+ entry. The aim of the present study was to characterize the modality of Ca2+ entry in the presence of high extracellular K+ concentration ([K+]o). A rise in [K+]o from 5 to > or = 50 mM induced a rapid and marked increase in the release of hCG and hPL from human term placental explants. The stimulatory effects of an excess [K+]o on the release of hCG and hPL were blocked in the absence of extracellular Ca2+ or in the presence of 0.5 mM Co2+. The presence of 50 microM methoxyverapamil, 20 microM nifedipine or 40 microM Cd2+ in the medium inhibited the stimulatory effects of [K+]o addition. Lastly, 40 microM Ni2+ failed to affect the increases in hCG and hPL releases elicited by [K+]o addition. Our data clearly show that a rise in [K+]o stimulates the release of hCG and hPL from placental explants. These secretory effects can be viewed as resulting from a Ca2+ entry through voltage-sensitive Ca2+ channels of the L-type.
authors.affiliation: Research Laboratory on Reproduction, Faculty of Medicine (CP-626), Free University of Brussels, (ULB), Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Meuris
authors.forename: B
authors.initials: B
authors.lastname: Polliotti
authors.forename: C
authors.initials: C
authors.lastname: Robyn
authors.forename: P
authors.initials: P
authors.lastname: Lebrun
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D005711:Gallopamil / Q000494:pharmacology; D006801:Humans; D009543:Nifedipine / Q000494:pharmacology; D009924:Organ Culture Techniques; D010920:Placenta / Q000378:metabolism*; D010928:Placental Lactogen / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D015220:Calcium Channels; D006063:Chorionic Gonadotropin; D005711:Gallopamil; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D010928:Placental Lactogen; D009543:Nifedipine; D011188:Potassium; D002118:Calcium