Proline-14C was administered to five adult rhesus monkeys, and the degradation of collagen was followed by the excretion of hydroxyproline-14C. The results suggested the presence of at least three separate pools of collagen with half-lives of 1 to 2, 2 to 3, and 50 to 70 days. The monkeys were killed after 44 days; at that time the specific activity of the hydroxyproline-14C in urine was found to be four to five times that of the hydroxyproline in soluble collagen and 81 to 93% that of hydroxyproline in insoluble collagen. The relationships between urinary hydroxyproline and the degradation of collagen were similar to those previously demonstrated in rats.
Louis V. Avioli, Darwin J. Prockop