Platelet-derived growth factor and multiplication-stimulating activity II, but not multiplication-stimulating activity III-2, stimulate [3H]thymidine and [35S]sulphate incorporation by fetal rat costal cartilage in vitro.
The actions of partially purified porcine platelet-derived growth factor (PDGF) and highly purified multiplication-stimulating activity (MSA) II and MSA III-2, which are somatomedins, were investigated on the incorporation of [3H]thymidine and [35S]sulphate by fetal rat costal cartilage in vitro. This was compared with their effects in the presence of 1% fetal calf serum (FCS) on the uptake of thymidine by growth-arrested fetal rat fibroblasts. Platelet-derived growth factor at concentrations of 0.21-21 micrograms/l enhanced the incorporation of both isotopes by fetal cartilage in the presence of 1% FCS, but had an inconsistent action on thymidine uptake and no significant action on sulphate uptake in serum-free medium. Platelet-derived growth factor promoted thymidine uptake by growth-arrested, isolated fetal rat fibroblasts. Multiplication-stimulating activity II (10-100 micrograms/l) stimulated the uptake of thymidine and sulphate by fetal cartilage in medium containing 1% FCS but had no consistent action in serum-free medium, although MSA II and PDGF had a synergistic effect on thymidine uptake in the absence of serum. Multiplication-stimulating activity III-2 had no consistent action on thymidine or sulphate incorporation by fetal cartilage in either serum-free or serum-supplemented medium. However, the same preparation of MSA III-2 stimulated the uptake of [3H]thymidine into fetal rat fibroblasts with a half-maximal response at a concentration of 5-10 micrograms/l. The results identify PDGF as a possible mitogenic agent for fetal rat connective tissues in vitro and show a differential sensitivity of fetal cartilage to MSA peptides.
D000818:Animals; D002356:Cartilage / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D002478:Cells, Cultured; D005333:Fetus; D005347:Fibroblasts / Q000378:metabolism; D007335:Insulin-Like Growth Factor II; D010455:Peptides / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000494:pharmacology*; D013268:Stimulation, Chemical; D013431:Sulfates / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism*
D010455:Peptides; D010982:Platelet-Derived Growth Factor; D013002:Somatomedins; D013431:Sulfates; D007335:Insulin-Like Growth Factor II; D013936:Thymidine