Different tissue uptake after administration of proline and hydroxyproline in neonatal piglets.

Using whole body autoradiography and impulse counting technique, distribution of intramuscularly administered C-DL-hydroxyproline and C-L-proline in newborn piglets was compared. The main excretion route of hydroxy-proline was via the kidneys. Hydroxyproline or its metabolic products were excreted at quite another rate by the liver than was proline. Skeletal muscles and myocardium showed a lowered ratio of proline to hydroxyproline. A difference in favour of hydroxyproline in passing the blood-brain barrier was shown. Contrary to proline hydroxyproline yielded a low C-level in the skeletal tissues. The possibilities of an incomplete hydroxylation of proline as an aetiological factor in the origin of skeletal disorders are discussed.