title: Activation of Cl- channels by human chorionic gonadotropin in luteinized granulosa cells of the human ovary modulates progesterone biosynthesis.
abstract: Chloride permeability pathways and progesterone (P4) secretion elicited by human chorionic gonadotropin (hCG) in human granulosa cells were studied by electrophysiological techniques and single-cell volume, membrane potential and Ca2+i measurements. Reduction in extracellular Cl(-) and equimolar substitution by the membrane-impermeant anions glutamate or gluconate significantly increased hCG-stimulated P4 accumulation. A similar result was achieved by exposing the cells to hCG in the presence of a hypotonic extracellular solution. Conversely, P4 accumulation was drastically reduced in cells challenged with hCG exposed to a hypertonic solution. Furthermore, conventional Cl(-) channel inhibitors abolished hCG-mediated P4 secretion. In contrast, 25-hydroxycholesterol-mediated P4 accumulation was unaffected by Cl(-) channel blockers. In human granulosa cells, hCG triggered the activation of a tamoxifen-sensitive outwardly rectifying Cl(-) current comparable to the volume-sensitive outwardly rectifying Cl(-) current. Exposure of human granulosa cells to hCG induced a rapid 4,4'-diisothiocyanatostilbene-2,2-disulphonic acid-sensitive cell membrane depolarization that was paralleled with an approximately 20% decrease in cell volume. Treatment with hCG evoked oscillatory and nonoscillatory intracellular Ca2+ signals in human granulosa cells. Extracellular Ca2+ removal and 4,4'-diisothiocyanatostilbene-2,2-disulphonic acid abolished the nonoscillatory component while leaving the Ca2+ oscillations unaffected. It is concluded that human granulosa cells express functional the volume-sensitive outwardly rectifying Cl(-) channels that are activated by hCG, which are critical for plasma membrane potential changes, Ca2+ influx, and P4 production.
authors.affiliation: Centro de Estudios Moleculares de la Célula and Instituto de Ciencias Biomédicas, Escuela de Medicina, Universidad de Valparaíso, Valparaíso, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Olivero
authors.forename: Elías
authors.initials: E
authors.lastname: Leiva-Salcedo
authors.forename: Luigi
authors.initials: L
authors.lastname: Devoto
authors.forename: Andrés
authors.initials: A
authors.lastname: Stutzin
mesh_terms: D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D018118:Chloride Channels / Q000378:metabolism* / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004594:Electrophysiology; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D006801:Humans; D034461:Luteinization / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000096:biosynthesis*
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D006063:Chorionic Gonadotropin; D011374:Progesterone; D002118:Calcium