Cytosolic free calcium levels in cultured pituitary cells separated by centrifugal elutriation: Effect of gonadotropin-releasing hormone

Rona Limor, Dan Ayalon, Alessandro M. Capponi, Gwen V. Childs, Zvi Naor*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

The cytosolic concentration of free Ca2+ ([Ca2+]i) in normal rat pituitary cells separated by centrifugal elutriation was monitored with the fluorescent Ca2+ indicator Quin 2. GnRH (10-7 M) induced a rapid rise (6–8 sec) in the gonadotroph's [Ca2+]i, followed by a plateau phase of prolonged elevated [Ca2+]i which lasted about 15 min. The stimulatory effect of GnRH was dose dependent, with an ED50 of 10-9 M, and was blocked by the potent antagonist [Dp-Glu1.pclPhe2.DTrp3,6]GnRH. GnRH elevated [Ca2+]iOnly in gonadotroph- enriched cell fractions, whereas TRH and GH-releasing factor (GRF) elevated [Ca2+]i in mammotroph- and somatotroph- enriched cells fractions, respectively. A rapid increase (first phase) in [Ca2+]i induced by GnRH was observed in Ca2+-free medium containing EGTA, but this rapid phase was terminated within 2 min. Readdition of Ca2+ to the medium induced a second slower rise in [Ca2+]i (plateau phase). Addition of K+ caused a rapid rise in [Ca2+]i, which was dependent on extracellular Ca2+, but was not affected by prior stimulation with GnRH. On the other hand, stimulation of gonadotroph's [Ca2+]i response by GnRH desensitized the cells to a subsequent GnRH challenge within the time frame studied. These findings indicate an elevation of [Ca2+]i induced by GnRH, TRH, and GRF in their respective separated target cells in the rat pituitary. The rise in [Ca2+]i in GnRH-stimulated gonadotrophs originates partly from intracellular Ca2+ pools and partly from influx of Ca2+ across the cell membrane.

Original languageEnglish
Pages (from-to)497-503
Number of pages7
JournalEndocrinology
Volume120
Issue number2
DOIs
StatePublished - Feb 1987

Funding

FundersFunder number
Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentR01HD016279

    Fingerprint

    Dive into the research topics of 'Cytosolic free calcium levels in cultured pituitary cells separated by centrifugal elutriation: Effect of gonadotropin-releasing hormone'. Together they form a unique fingerprint.

    Cite this