Journal of Cell Science, Vol 21, Issue 1 107-117, Copyright © 1976 by Company of Biologists

JOURNAL ARTICLES

Patterns of calcium localization in pancreatic endocrine cells

M Ravazzola, F Malaisse-Lagae, M Amherdt, A Perrelet, WJ Malaisse and L Orci

Subcellular calcium localization in the dndocrine cells of rat pancreas was studied by the pyroantimonate precipitation technique. Calcium-containing electron-dense deposits in the endocrine cells were mostly found within secretory granules and along the plasma membrane, but their pattern of distribution in A-, B- and D-cells displayed qualitative and quantitative differences. In B-cells, numerous secretory granules contained deposits located in the halo surrounding the granule core. In A-cells, only few granules contained precipitates in their halo, whereas in D-cells, deposits were situated in the dense core of the secretory granules. Deposits along the plasma membrane occurred generally on the outer leaflet of the plasma membrane of B- and D-cells and on the inner leaflet of that of A-cells. In islets incubated at a high glucose concentration or in the presence of the calcium ionophore A23187, the number of beta granules containing precipitates was significantly increased. By contrast, only few deposits were observed in B-cells incubated in calcium-deprived medium enriched with EGTA. These findings indicate that: the pattern of calcium localization varies in different islet cell types; in B-cells the secretory granules represent one of the major stores of intracellular calcium; and that this store undergoes changes in conditions which alter insulin release.

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				B Hellman, J Sehlin, and I. Taljedal Calcium and secretion: distinction between two pools of glucose-sensitive calcium in pancreatic islets Science, December 24, 1976; 194(4272): 1421 - 1423. [Abstract] [PDF]