The effect of inorganic orthophosphate on the rates of collagen formation and degradation in bone and cartilage in tissue culture.

Abstract

ABSTRACT Using a tissue culture system, the effect of the concentration of inorganic orthophosphate [(Pi)] in the tissue culture medium on the synthesis and degradation of collagen in bone and cartilage was studied. A consistent observation was that the rate of synthesis of bone and cartilage collagen was markedly reduced when the [(Pi)] concentration of the tissue culture medium was lowered to 0.32 mm. In addition, less of the collagen that was synthesized was incorporated into the tissue. Increasing the [(Pi)] concentration beyond 1.30 mm (a concentration at which this effect was reversed) to concentrations as high as 3.23 mm of [(Pi)] did not significantly alter the rate of collagen synthesis in cartilage or bone. The [(Pi)] concentration in the tissue culture medium affected the rate at which the older structural collagen was degraded only when the rate of bone collagen resorption was elevated by increasing the O2 tension in the culture chamber and especially when, in addition to increasing the O2 ten...