Incorporation of [3H]glucosamine into glycosaminoglycans in different cell culture conditions by rabbit aortic smooth muscle cells

This study sought to elucidate the optimal cell culture conditions for studies concerned with the incorporation of ³H]glucosamine into glycosaminoglycans by rabbit aortic smooth muscle cells. The incorporation of radioactivity into extracellular sulphated glycosaminoglycans was linear for at least 72 h and that into pericellular sulphated glycosaminoglycans for up to 24 h. The incorporation of radiolabel into hyaluronic acid was linear only up to 12 h. In the exponential growth phase the incorporation of ³H]glucosamine into sulphated glycosaminoglycans and hyaluronic acid proved to be less marked than in the stationary growth phase, but the highest values were nevertheless obtained immediately after trypsinisation. When studied in the stationary growth phase, cell density and incorporation of ³H]glucosamine were positively correlated in the case of hyaluronic acid, but in the case of sulphated glycosaminoglycans there was a negative correlation. The serum concentration of the incubation medium and the incorporation of radioactivity into hyaluronic acid were positively related. With sulphated glycosaminoglycans this was the case only after a 7-day preincubation in the different serum concentrations. when incorporation was studied without preincubation, the incorporation of radioactivity into sulphated glycosaminoglycans proved to be negatively associated with the serum concentration of the medium. The environmental pH of the cells was associated with the incorporation of radioactivity into hyaluronic acid and sulphated glycosaminoglycans in that between pH values 6.8 and 7.9 the incorporation of radioactivity increased when the pH of the medium was raised.