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

Using whole body autoradiography and impulse counting technique, distribution of intramuscularly administered 14C-DL-hydroxyproline and 14C-L-proline in newborn piglets was compared. The main excretion route of hydroxyproline 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 lower 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 14C-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. (author)