Reversible decrease of collagen crosslinking by protein low diet and aminoacetonitrile--effect of D-penicillamine and prednisolone on the rise of crosslinks.

After ending a 4-week period of low-protein diet with or without aminoacetonitrile (AAN), the tail tendons of rats showed an increase of hydroxylysinonorleucine (HLNL) together with other unidentified reducible crosslinks. The binding of dihydroxylysinonorleucine type (DHLNL) was an exception: its content remained unchanged. It may be, assumed, therefore, that the procedures mentioned above act indiscriminately against all reducible crosslinks with the exception of DHLNL. The rise in crosslinks after the 4-week pretreatment was disturbed, when d-penicillamine was given, because it specifically inhibited the formation of HLNL. The content of other crosslink components was slightly increased above that of controls so that the absolute content of total isolated crosslinks increased in the presence of d-penicillamine. No statistically significant differences could be obtained under prednisolone.