Metabolism of gingival collagen in a rat

The remodeling of gingival tissue was measured by determining the incorporation of tritiated proline and the disappearance of tritium activity from proline and hydroxyproline for 18 days after administration of label. There was a rapid decrease in the tritium activity from gingiva which was paralleled by a decrease in the total activity of proline. The activity in collagen decreased sharply between the second and the fourth day but thereafter there was no change. The relative amount of activity increased from 24% at day 2 to 82% at 18 days postinjection, and as a result the specific activities of hydroxyproline and proline were similar after 12 days. Thus collagen appeared to be the more stable component in the gingivae than previously reported. However, the rapid loss of label in the first four days suggested that there may be very marked regional variation in the metabolism of collagen and that more than one metabolic pool of collagen was present.