Role of increase in intracellular calcium in PTH-induced homologous desensitization in UMR-106 cells.

Abstract

Effects of increase in intracellular calcium on PTH-induced homologous desensitization were investigated using calcium ionophores. Pretreatment of UMR-106 cells (rat osteoblast like osteosarcoma cell line) with calcium ionophores (A23187 or ionomycin) for 6h resulted in approximately 50% decrease of PTH-stimulated cAMP production. PTH receptor binding, assessed with 125I-[Nle8,Nle18,Tyr34]PTH-(1-34) as radioligand, was significantly decreased in 10(-6) M calcium ionophore-pretreated (for 6h) cells without affecting the dissociation constant (Kd) for PTH. Minimal effective treatment period was 2h and similar inhibitory effect was observed in 12h-treated cells. These data suggest that increase in intracellular calcium might also act on PTH receptor in the similar manner as protein kinase C activation to induce desensitization.

• Authors: K Ikeda, T Sugimoto, M Fukase, T Fujita
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 176 Issue 3 Pg. 1033-6 (May 15 1991) ISSN: 0006-291X [Print] United States
• PMID: 1645535 (Publication Type: Journal Article)

Chemical References

• Parathyroid Hormone
• Receptors, Cell Surface
• Receptors, Parathyroid Hormone
• Calcimycin
• Ionomycin
• Cyclic AMP
• Calcium

Topics

• Animals
• Calcimycin (pharmacology)
• Calcium (metabolism)
• Cell Line
• Cyclic AMP (metabolism)
• Ionomycin (pharmacology)
• Kinetics
• Osteoblasts (metabolism)
• Osteosarcoma
• Parathyroid Hormone (metabolism, pharmacology)
• Rats
• Receptors, Cell Surface (drug effects, metabolism)
• Receptors, Parathyroid Hormone