Age-related differences in the metabolism of proteoglycans in bovine articular cartilage explants maintained in the presence of insulin-like growth factor I.
Articular cartilage explants from bovine calf and steer were cultured for up to 19 days in medium with or without 20% fetal bovine serum (FBS) or insulin-like growth factor I (IGF-I). Lower concentrations of IGF-I were required for maximal stimulation of PG synthesis in calf than in steer. In calf, but not in steer, IGF-I was as effective as 20% FBS in stimulating PG synthesis. The stimulation by IGF-I or FBS was not accompanied at either age by alterations in the composition of the aggregating PGs nor by changes in the proportions of CS-rich and CS-poor PG subpopulations. In calf, IGF-I and FBS did not markedly alter the rate of turnover of either the 35S-PGs synthesized in vitro or the unlabeled PGs. In steer, explants cultured in the absence of IGF-I or FBS exhibited very fast rates of turnover and depletion of matrix PG with time; IGF-I and FBS were both effective in reducing the turnover rate of 35S-PGs and unlabeled PGs and in preventing PG depletion.
Barone-Varelas
J
J
Department of Biochemistry, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612.
Schnitzer
T J
TJ
Meng
Q
Q
Otten
L
L
Thonar
E J
EJ
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002358:Cartilage, Articular / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D002499:Centrifugation, Density Gradient; D002809:Chondroitin Sulfates / Q000032:analysis / Q000378:metabolism; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D005312:Fetal Blood; D006207:Half-Life; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000494:pharmacology*; D007632:Keratan Sulfate / Q000032:analysis / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D011509:Proteoglycans / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry
D011509:Proteoglycans; D007334:Insulin-Like Growth Factor I; D002809:Chondroitin Sulfates; D007632:Keratan Sulfate