ISSN:
1432-0827
Keywords:
Osteoclasts
;
Cytoplasmic Ca2+
;
Calcium receptor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
,
Physics
Notes:
Summary It has been reported that osteoclastic function is regulated by calcium-induced alterations in cytoplasmic free calcium ([Ca2+]i), possibly through a specific receptor. We have investigated whether osteoclasts, isolated from neonatal rat long bones, possess the divalent cation-receptor that has been demonstrated on parathyroid cells. Studies with fura-2 loaded adherent single cells showed that an increase in extracellular Ca2+ ([Ca2+]e) from 0.5 mM to 10 mM resulted in an increase in [Ca2+]i in isolated rat osteoclasts, from a basal value of 94.7±16.2 to 150.6±22.4 nM (means±SEM; n=14). The shape and time course of the [Ca2+]i increase varied considerably from cell to cell. Less than half of the cells responded with a rapid transient increase whereas the rest responded with a slow increase that reached a plateau within 1–2 minutes. When [Ca2+]e was changed back to 0.5 mM, a slow decrease in [Ca2+]i was monitored. Immunohistochemical staining with two different monoclonal antibodies, recognizing the putative Ca2+ receptor on parathyroid cells, did not indicate any staining on freshly isolated rat osteoclasts. Thus, our data demonstrate that an increase in [Ca2+]e causes an elevation of [Ca2+]i in osteoclasts. This increase is not mediated via the putative cation-receptor found on parathyroid cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00295950
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