ZINC IS A POTENT INHIBITOR OF OSTEOCLASTIC BONE-RESORPTION IN-VITRO

It is well established that zinc, an essential trace element, plays an important role in growth and stimulates bone formation. However, the effects of zinc on bone resorption have received little attention, We studied its effects on isolated rat osteoclasts, Unexpectedly, osteocl asts were exquisitely sensitive to zinc, with a significant decrease i n bone resorption occurring at concentrations as low as 10(-14) M, Thi s effect was specific for zinc and was not observed with the other tra nsitional or alkaline metals studied. There was no evidence of toxicit y at concentrations up to 10(-4) M, Zinc also completely abolished the stimulatory effect of parathyroid hormone, Zinc is therefore a highly patent and selective inhibitor of osteoclastic bone resorption in vit ro. The mode of action remains to be established and may represent a n ovel inhibitory mechanism in the osteoclast.