Stimulation of Cartilage Inorganic Pyrophosphate Elaboration by Ascorbate

Lawrence M. Ryan, Indira Kurup, Herman S. Cheung

Research output: Contribution to journalArticle

22 Scopus citations


Ascorbate (0-500 μM) stimulates synthesis and secretion of collagen by cartilage explants in a dose-dependent fashion as estimated by [3H]proline incorporation. Concurrent elaboration of inorganic pyrophosphate (PPi) parallels [3H]proline incorporation (< 0.001, Wilcoxon rank sum). The effect on proline and PPi is abolished by ascorbate oxidase. Another reducing agent, vitamin E, did not promote PPi accumulation about cartilage. Inhibitors of collagen synthesis, including monensin, tumor necrosis factor α, and 2',2'-dipyridyl also inhibited PPi elaboration. Cycloheximide (1 μg/ml) inhibited the ascorbate stimulated PPi elaboration 54% but did not attenuate the secretion of PPi by unstimulated cartilage. Cosecretion of collagen and PPi by chondrocytes may explain these results. Moreover, at least two pathways exist for PPi elaboration, a cycloheximide sensitive path and another independent of new protein synthesis.

Original languageEnglish (US)
Pages (from-to)276-281
Number of pages6
Issue number4
StatePublished - 1991


  • ascorbate
  • cartilage
  • inorganic pyrophosphate

ASJC Scopus subject areas

  • Rheumatology

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