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Effect of Metabolic Acidosis on the Potassium Content of Bone
Author(s) -
Bushinsky David A.,
Gavrilov Konstantin,
Chabala Jan M.,
Featherstone John D. B.,
LeviSetti Riccardo
Publication year - 1997
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1997.12.10.1664
Subject(s) - chemistry , potassium , endocrinology , resorption , medicine , bone mineral , calcium , bone resorption , metabolic acidosis , osteoporosis , biology , organic chemistry
Metabolic acidosis induces resorption of cultured bone, resulting in a net efflux of calcium (Ca) from the bone and an apparent loss of mineral potassium (K). However, in these organ cultures, there is diffusion of K between the medium and the crystal lattice, causing difficulty in interpretation of the acid‐induced changes in mineral ion composition. To determine the effects of acidosis on bone mineral K, we injected 4‐day‐old neonatal mice with pure stable isotope 41 K, equal to ∼5% of their total body K. Calvariae were dissected 24 h later and then cultured for 24 h in medium without added 41 K, either at pH ∼7.4 (Ctl) or at pH ∼7.1 (Ac), with or without the osteoclastic inhibitor calcitonin (3 × 10 −9 M, CT). The bone isotopic ion content was determined with a high‐resolution scanning ion microprobe utilizing secondary ion mass spectrometry. 41 K is present in nature at 6.7% of total K. The injected 41 K raised the ratio of bone 41 K/( 39 K+ 41 K) to 9.8 ± 0.5% on the surface (ratios of counts per second of detected secondary ions, mean ±95% confidence interval) but did not alter the ratio in the interior (6.9 ± 0.4%), indicating biological incorporation of the 41 K into the mineral surface. The ratios of 41 K/ 40 Ca on the surface of Ctl calvariae was 14.4 ± 1.2, indicating that bone mineral surface is rich in K compared with Ca. Compared with Ctl, Ac caused a marked increase in the net Ca efflux from bone that was blocked by CT. Ac also induced a marked fall in the ratio of 41 K/ 40 Ca on the surface of the calvariae (4.3 ± 0.5, p < 0.01 vs. Ctl), which was partially blocked by CT (8.2 ± 0.9, p < 0.01 vs. Ctl and vs. Ac), indicating that Ac causes a greater release of bone mineral K than Ca which is partially blocked by CT. Thus, bone mineral surface is rich in K relative to Ca, acidosis induces a greater release of surface mineral K than Ca, and osteoclastic function is necessary to support the enriched levels of surface mineral K in the presence of acidosis.