The effects of extracellular pH on bone resorption by avian osteoclasts in vitro

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Abstract
It has previously been reported that low extracellular pH stimulates the excavation of resorption lacunae by rodent osteoclasts in vitro. Using avian bone cells in a similar in vitro assay we have demonstrated that osteoclast activity is optimal at pH 7.20–7.40 and is inhibited at extremes of pH (7.60). Over the first 24 h of incubation at low pH there may be an increase in osteoclastic resorption but to a lesser extent than that reported for rodent cells. However, after 24–30 h in culture there is little or no further increase in bone resorption, presumably due to a cytotoxic effect of low pH acting either on the osteoclast directly or via nonosteoclastic bone cells. In contrast to a previous report, in which preincubation of wafers for 24 h had no effect on bone resorption, we found that preincubation of bone substrates at pH 6.50 for longer periods enhances subsequent resorption at pH 7.20.
Funding Information
  • North West Cancer Research Fund