title: Ascorbic acid stimulates the resorption of canine articular cartilage induced by a factor derived from activated rabbit macrophages.
abstract: Articular cartilage explants from the knees of mongrel dogs release 5-10% of their proteoglycan content spontaneously when cultured for 4 days in serum-free modified Bigger's medium. A factor synthesized and secreted by lipopolysaccharide-stimulated rabbit macrophages can stimulate this release of proteoglycan by 2 to 3-fold. The release of proteoglycan in response to macrophage factor is maximal in the presence of 1.5-50 micrograms/ml L-ascorbic acid. In the absence of ascorbate, or with high levels of ascorbate (150 micrograms/ml), the effect of the factor is diminished by 50%. D-isoascorbate, reduced glutathione, or dithiothreitol cannot substitute for L-ascorbate in producing this effect, while dehydroascorbate can.
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000378:metabolism*; D002809:Chondroitin Sulfates / Q000378:metabolism; D003470:Culture Media; D046508:Culture Techniques; D004285:Dogs; D007719:Knee Joint; D008264:Macrophages / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism; D013045:Species Specificity; D013268:Stimulation, Chemical
chemical_list: D003470:Culture Media; D011509:Proteoglycans; D002809:Chondroitin Sulfates; D001205:Ascorbic Acid