[Animal experiments on the relationship between urinary excretion of hydroxyproline and serum hydroxyproline fractions].

Hydroxyproline excreted withh the urine and the free and peptide-bound hydroxyproline in the serum originate from collagen catabolism in the connective tissue. The relation of protein-bound hydroxyproline in the serum to the collagen metabolism is still contradictory. In normal and lathyritic rats the time dependent changes of specific hydroxyproline activity in the urine and serum after intraperitoneal application of C-14-proline were determined. In normal rats the main part of hydroxyproline excreted in urine and of the protein-bound hydroxyproline in serum have corresponding half-life periods of 0,6-0,7 days and co-ordinate with the neutral salt soluble collagen. Also in lathyritic rats with their increased amount of neutral salt soluble collagen due to an increase collagen synthesis and a retarded transition from soluble to insoluble collagen these two parameters of collagen metabolisms are in agreement.