Thyrotropin-releasing hormone mobilizes Ca2+ from endoplasmic reticulum and mitochondria of GH3 pituitary cells: characterization of cellular Ca2+ pools by a method based on digitonin permeabilization.
- 1 October 1982
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 79 (20), 6294-6298
- https://doi.org/10.1073/pnas.79.20.6294
Abstract
Treatment of 45Ca2+-loaded [rat] GH3 pituitary [tumor] cells with various concentrations of digitonin revealed discrete pools (I and II) of cellular 45Ca2+ defined by differing detergent sensitivities. Markers for cytosol and intracellular organelles indicated that the 2 45Ca2+ pools were correlated with the 2 major cellular Ca2+-sequestering organelles, endoplasmic reticulum (I) and mitochondria (II). Studies with various inhibitors were consistent with these assignments. Mitochondrial uncouplers preferentially depleted 45Ca2+ pool II while trifluoperazine selectively depleted 45Ca2+ pool I. Control experiments indicated that translocation of in situ organellar 45Ca2+ during and after permeabilization was negligible. The digitonin-permeabilization method was used to examine the effect of TRH treatment on intracellular Ca2+-pools of GH3 pituitary cells. TRH rapidly depleted both endoplasmic reticulum and mitochondrial exchangeable Ca2+ by 25-30%. The 45Ca2+ loss from both pools was maximal by 1 min after TRH addition and was followed by a recovery phase; mitochondrial 45Ca2+ content returned to control levels by 30 min. Previous treatment of cells with the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxy-phenylhydrazone blocked TRH-induced 45Ca2+ efflux from mitochondria, while previous treatment with valinomycin, an agent that depleted both 45Ca2+ pools, blocked any additional effect of TRH on these pools, TRH rapidly promotes a net loss of exchangeable Ca2+ from GH3 cells as a result of hormone-induced mobilization of Ca2+ from endoplasmic reticulum and mitochondria.This publication has 24 references indexed in Scilit:
- Regulation of free Ca2+ by liver mitochondria and endoplasmic reticulum.Journal of Biological Chemistry, 1980
- Hormonal effects on calcium homeostasis in isolated hepatocytes.Journal of Biological Chemistry, 1980
- Paradoxical effects of protein synthesis inhibitors on uridine uptake in cultured cells: Possible role of uncharged tRNA in regulating metabolismJournal of Cellular Physiology, 1980
- Markers for membranous cell components. The 6th International Subcellular Methology Form, Guildford/United Kingdom, 25-28 July 1978.1979
- [46] Clonal strains of hormone-producing pituitary cellsMethods in Enzymology, 1979
- Freeze-fracture identification of sterol-digitonin complexes in cell and liposome membranes.The Journal of cell biology, 1978
- Phosphodiesterase protein activator stimulates calcium transport in cardiac microsomal preparations enriched in sarcoplasmic reticulumBiochemical and Biophysical Research Communications, 1978
- Action potentials occur in cells of the normal anterior pituitary gland and are stimulated by the hypophysiotropic peptide thyrotropin-releasing hormone.Proceedings of the National Academy of Sciences, 1977
- Inositol phospholipids and cell surface receptor functionBiochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1975
- The inhibition of mitochondrial calcium transport by lanthanides and Ruthenium RedBiochemical Journal, 1974