Potassium concentration in membrane-associated particles in the epiphyseal growth plate |
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Authors: | Dr R H Barckhaus P F Schmidt P Quint H J Höhling |
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Institution: | (1) Institut für Medizinische Physik der Universität, Münster, Bundesrepublik Deutschland;(2) Institut für Med. Physik der Universität, Hüfferstr. 68, D-4400 Münster, Federal Republic of Germany |
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Abstract: | Summary Electron-dense particles with a diameter of 50–200 nm have been observed at the cell membrane of chondrocytes in the zone of the initiation and advance of mineralization, using the dark field STEM mode. Electronprobe x-ray microanalysis and laser microprobe mass analysis indicate that these particles contain predominantly K and Na. They appear only in dry thin sections of shock-frozen, freeze-dried embedded tissue and not in sections of water-treated samples; hence they contain water-extractable potassium and sodium. The function of the two elements at these special sites is not yet clear. On the one hand, they might reflect exocytotic processes connected with a Na-K-ATPase; on the other hand, they might exist as a transitory state before being replaced by Ca and phosphate in the mineralizing matrix and later transported elsewhere by the blood vessels.We thank the Deutsche Forschungsgemeinschaft for financial support |
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Keywords: | Growth plate Microprobe analysis Potassium Sodium Guinea pig |
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