Radioisotopic and morphometric evaluation of the effects of beta-aminopropionitrile on chick bone matrix formation and its mineralization.

Bones from 2-week-old chicks, fed a diet containing 0.05% beta-aminopropionitrile (beta-APN), were studied for 3H-tetracycline and 3H-proline incorporation at 7, 14 and 21 days of the experiment. Liquid scintillation counts showed a comparable amount of 3H-proline incorporation in the controls and experimentals. However, the incorporation of 3H-tetracycline was significantly lower in experimentals at all intervals. Fluorescent microscopy after cold tetracycline injections at similar intervals showed a comparable amount of linear bone apposition in controls and beta-APN-fed chicks. The bone ash content in beta-APN-fed chicks was lower at all intervals whereas the serum calcium level was similar to the controls. Microradiography showed that cortical and marrow areas, in cross sections, were not significantly different in the controls and beta-APN-fed chicks. On the basis of these data it is suggested that beta-APN at the dose used does not inhibit the bone matrix synthesis but inhibits its mineralization.