Ascorbic acid regulates multiple metabolic activities of cartilage cells.

Bones grow in length because of the activities of cartilage cells in the epiphyseal growth plate. We have examined selected events that occur in the growth cartilage by the use of cultured epiphyseal cells; we have also evaluated the influence of ascorbate on these activities. Our studies indicate that 1) ascorbate induces the expression of a unique collagen isoform, type X collagen; 2) ascorbate stimulates alkaline phosphatase activity of maturing chondrocytes; and 3) ascorbate regulates the energy status of the maturing chondrocyte. We have found that in the presence of ascorbate there is a change in oxidative activity. Thus, lactate formation is inhibited, there is an increase in the adenylate energy charge ratio, and there is an elevation in the activity of isocitrate dehydrogenase. The results of these studies point to multiple effects of vitamin C on chondrocyte maturation involving changes in protein synthesis and energy metabolism.