title: High extracellular calcium stimulates osteoclast-like cell formation and bone-resorbing activity in the presence of osteoblastic cells.
abstract: The present study was performed to examine the effect of the high concentration of extracellular calcium ([Ca2+]e) on osteoclast-like cell formation and bone-resorbing activity in the presence or absence of osteoblasts. High [Ca2+]e (3 and 5 mM) significantly stimulated osteoclast-like cell formation in osteoblast-containing mouse bone cell cultures, although high [Ca2+]e did not affect the formation of osteoclast-like cells from hemopoietic blast cells supported by granulocyte-macrophage colony-stimulating factor in mouse spleen cell cultures. The osteoclast-like cells, newly formed by high [Ca2+]e in the presence of osteoblasts, possessed the ability to form pits on the dentine slices. The conditioned medium from osteoblastic MC3T3-E1 cells treated with high [Ca2+]e (5 mM) significantly increased the formation of osteoclast-like cells from hemopoietic blast cells, compared with the control medium. Dantrolene, an inhibitor of calcium mobilization from the intracellular calcium pool, and indomethacin significantly blocked high [Ca2+]e-stimulated osteoclast-like cell formation in the presence of osteoblasts, although voltage-dependent calcium channel blockers and anti-insulin-like growth factor I antibody did not affect it. High [Ca2+]e, however, significantly stimulated the bone-resorbing activity of mature osteoclasts in osteoblast-containing mouse bone cell cultures, although high [Ca2+]e inhibited bone-resorbing activity in isolated rabbit osteoclasts. An increase in the extracellular magnesium concentration (5 mM) affected neither osteoclast-like cell formation nor bone-resorbing activity. In conclusion, high [Ca2+]e stimulated osteoclast-like cell formation and bone-resorbing activity of mature osteoclasts, presumably via osteoblasts.
authors.affiliation: Department of Medicine, Kobe University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kaji
authors.forename: T
authors.initials: T
authors.lastname: Sugimoto
authors.forename: M
authors.initials: M
authors.lastname: Kanatani
authors.forename: K
authors.initials: K
authors.lastname: Chihara
mesh_terms: D000818:Animals; D001862:Bone Resorption / Q000139:chemically induced*; D002118:Calcium / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects; D003620:Dantrolene / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D008815:Mice, Inbred Strains; D010006:Osteoblasts / Q000187:drug effects*; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects*; D011453:Prostaglandins / Q000502:physiology; D011817:Rabbits; D013268:Stimulation, Chemical
chemical_list: D002121:Calcium Channel Blockers; D011453:Prostaglandins; D007334:Insulin-Like Growth Factor I; D003620:Dantrolene; D002118:Calcium