Extracellular Ca2+ sensing by the osteoclast

M. Zaidi, A. S.M.T. Alam, C. L.H. Huang, M. Pazianas, C. M.R. Bax, B. E. Bax, B. S. Moonga, P. J.R. Bevis, V. S. Shankar

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71 Scopus citations


An increasing number of cell types appear to detect changes in the extracellular Ca2+ concentrationand and accordingly modify their function. We review recent evidence for the existence and function of such a mechanism in the osteoclast. Elevated external [Ca2+] in the mM range reduces bone resorption and results in motile changes in the cells. These changes may partly result from elevations of cytosolic [Ca2+] triggered through activation of a surface Ca2+ receptor. Closer analyses of the increases in cytosolic [Ca2+] associated with receptor activation are hindered by the action of this ion both as extracellular agonist and intracellular second messenger. Variations in the peak cytosolic [Ca2+] response to external Ca2+ with changes in cell membrane potential by K+ and valinomycin establish a contribution from extracellular Ca2+. Use of CIO4-, Ni2+ and Cd2+ as surrogate activators in low extracellular [Ca2+] indicate a contribution from Ca2+] release from intracellular stores as well. Such agonists also modify Ca2+ redistribution in other systems, such as skeletal muscle. Thus, we may gain insights into osteoclast extra-cellular Ca2+ detection and transduction from known features of more well-characterised cell systems.

Original languageEnglish
Pages (from-to)271-277
Number of pages7
JournalCell Calcium
Issue number4
StatePublished - Apr 1993
Externally publishedYes


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