Endocrinology, Vol 113, 324-328, Copyright © 1983 by Endocrine Society

ARTICLES

Inhibition of stimulated bone resorption by vanadate

NS Krieger and AH Tashjian Jr

We have previously reported that stimulated release of calcium (Ca) from bone is a sodium-dependent process. Partial support for this conclusion came from the observation that ouabain inhibited stimulated bone resorption as a result of inhibition of the Na,K-ATPase in bone. We now present additional supporting evidence from the results of experiments using vanadate, an ion known to inhibit the activity of Na,K-ATPase. Vanadate inhibited stimulated bone resorption in neonatal mouse calvaria. Inhibition occurred in a dose-dependent manner, and ortho-vanadate was 3-fold more potent than meta-vanadate. Ortho- vanadate was equally effective against several different stimulators of resorption, including PTH, prostaglandin E2, and 1,25- dihydroxycholecalciferol. PTH-stimulated bone resorption was inhibited with a Ki of about 9 microM. Stimulated Ca release was completely blocked whether vanadate was added at zero time or 24 h after the addition of a resorption-stimulating agent. Because the responses to vanadate were similar to those observed with ouabain, we conclude that vanadate is probably acting to inhibit stimulated resorption via inhibition of the Na,K-ATPase in bone.

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