Patterns of calcium localization in pancreatic endocrine cells

• Published in: Journal of cell science Vol. 21; no. 1; pp. 107 - 117
• Main Authors: Ravazzola, M, Malaisse-Lagae, F, Amherdt, M, Perrelet, A, Malaisse, W J, Orci, L
• Format: Journal Article
• Language: English
• Published: England 01.06.1976
• Subjects: Animals; Calcimycin - pharmacology; Calcium - analysis; Cell Nucleus - analysis; Cytoplasmic Granules - analysis; Egtazic Acid - pharmacology; Glucose - pharmacology; Golgi Apparatus - analysis; Histocytochemistry; Islets of Langerhans - analysis; Islets of Langerhans - drug effects; Islets of Langerhans - ultrastructure; Mitochondria - analysis; Rats
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.21.1.107

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.