PMID: 9159921Apr 1, 1997Paper

Calcium in secretory vesicles of neurohypophysial nerve endings: quantitative comparison by X-ray microanalysis of cryosectioned and freeze-substituted specimens

Journal of Microscopy
S ThirionG Nicaise

Abstract

The calcium content of individual secretory vesicles in rat neurohypophysial nerve endings was measured by quantitative electron probe X-ray microanalysis. Directly frozen control and potassium-depolarized isolated endings were analysed using two presumably equivalent preparative techniques: (1) freeze-substitution in presence of oxalic acid followed by sectioning of resin-embedded pellets; or (2) direct cryosectioning of the frozen pellets followed by freeze-drying in the column of the microscope. In the pellets of stimulated endings, both approaches revealed an increase in the calcium content of neurosecretory vesicles. This increase was statistically more significant in the specimens prepared by cryosectioning, probably because in this case the contribution of 'dead' nerve endings could be eliminated on the basis of excessive cytoplasmic sodium and chloride. The results demonstrate that an increase in cytosolic calcium can lead to an increase in intravesicular calcium, and that when this occurs, it occurs within a subpopulation of vesicles in a given nerve ending. In addition, measured intravesicular calcium was dispersed over a wide range of concentrations, as predicted by the hypothesis of intravesicular calcium priming. W...Continue Reading

Citations

Mar 17, 1999·Proceedings of the National Academy of Sciences of the United States of America·S ThirionG Nicaise
Jun 9, 2001·Cell Calcium·J Meldolesi, F Grohovaz
Feb 19, 2011·Micron : the International Research and Review Journal for Microscopy·Antje BiesemeierOliver Eibl
Dec 22, 1999·Cell Calcium·S RaisonG Nicaise

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