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Co-localization of L-type Ca2+ channels and insulin-containing secretory granules and its significance for the initiation of exocytosis in mouse pancreatic B-cells

Author:
  • K Bokvist
  • Lena Eliasson
  • C Ammala
  • Erik Renström
  • Patrik Rorsman
Publishing year: 1995
Language: English
Pages: 50-57
Publication/Series: EMBO Journal
Volume: 14
Issue: 1
Document type: Journal article
Publisher: Oxford University Press

Abstract english

We have monitored L-type Ca2+ channel activity, local cytoplasmic Ca2+ transients, the distribution of insulin-containing secretory granules and exocytosis in individual mouse pancreatic B-cells. Subsequent to the opening of the Ca2+ channels, exocytosis is initiated with a latency < 100 ms. The entry of Ca2+ that precedes exocytosis is unevenly distributed over the cell and is concentrated to the region with the highest density of secretory granules. In this region, the cytoplasmic Ca2+ concentration is 5- to 10-fold higher than in the remainder of the cell reaching concentrations of several micromolar. Single-channel recordings confirm that the L-type Ca2+ channels are clustered in the part of the cell containing the secretory granules. This arrangement, which is obviously reminiscent of the 'active zones' in nerve terminals, can be envisaged as being favourable to the B-cell as it ensures that the Ca2+ transient is maximal and restricted to the part of the cell where it is required to rapidly initiate exocytosis whilst at the same time minimizing the expenditure of metabolic energy to subsequently restore the resting Ca2+ concentration.

Keywords

  • Biochemistry and Molecular Biology

Other

Published
  • Islet cell exocytosis
  • Islet patophysiology
  • Islet cell physiology
  • ISSN: 1460-2075
Erik Renström
E-mail: erik.renstrom [at] med.lu.se

Deputy head of department

Department of Clinical Sciences, Malmö

+46 40 39 11 57

+46 40 39 11 57

Principal investigator

Islet patophysiology

+46 40 39 11 57

+46 40 39 11 57

20-3-308

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