Abstract
Metaphyses and diaphyses removed from rats treated with 0.1% aminoacetonitrile diet for 9 days were incubated separately in Krebs-Ringer bicarbonate buffer. The amount of total hydroxyproline released from diaphyses into medium decreased by parathyroidectomy in lathyritic rats, but not from metaphyses as described previously. Collagen resorption in diaphyses depended more on parathyroid function. The sensitivity for collagenase inhibitors on collagen resorption of diaphyses was different from that of metaphyses. Treatment of lathyritic rats with calcitonin (0.75 MRC U/100g body weight 3, 2 and 1 hr respectively before sacrifice) also resulted in inhibition of the amount of total hydroxyproline released from diaphyses into the medium, as shown in the case of metaphyses. Therefore, it was suggested that calcitonin counteracted the parathyroid hormone-induced collagen resorption in diaphyses.
Calcitonin decreased the amount of total hydroxyproline released from lathyritic metaphyses into the medium, but did not significantly decrease the amount of hexosamine. This result indicated that inhibitory effect of calcitonin on matrix resorption of metaphyses was more selective on collagen than on hexosamine-containing substances. Bone collagenase inhibitors (EDTA and cysteine) also diminished the amount of total hydroxyproline released from lathyritic metaphyses into the medium.
From these results it may be concluded that calcitonin regulates directly or indirectly bone collagenase in osteolathyrism.
