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CaM kinase II-dependent mobilization of secretory granules underlies acetylcholine-induced stimulation of exocytosis in mouse pancreatic B-cells

Author:
  • Jesper Gromada
  • Marianne Hoy
  • Erik Renström
  • Krister Bokvist
  • Lena Eliasson
  • Sven Göpel
  • Patrik Rorsman
Publishing year: 1999
Language: English
Pages: 745-759
Publication/Series: Journal of Physiology
Volume: 518
Issue: 3
Document type: Journal article
Publisher: The Physiological Society

Abstract english

1. Measurements of cell capacitance were used to investigate the mechanisms by which acetylcholine (ACh) stimulates Ca2+-induced exocytosis in single insulin-secreting mouse pancreatic B-cells. 2. ACh (250 microM) increased exocytotic responses elicited by voltage-clamp depolarizations 2.3-fold. This effect was mediated by activation of muscarinic receptors and dependent on elevation of the cytoplasmic Ca2+ concentration ([Ca2+]i) attributable to mobilization of Ca2+ from intracellular stores. The latter action involved interference with the buffering of [Ca2+]i and the time constant (tau) for the recovery of [Ca2+]i following a voltage-clamp depolarization increased 5-fold. As a result, Ca2+ was present at concentrations sufficient to promote the replenishment of the readily releasable pool of granules (RRP; > 0.2 microM) for much longer periods in the presence than in the absence of the agonist. 3. The effect of Ca2+ on exocytosis was mediated by activation of CaM kinase II, but not protein kinase C, and involved both an increased size of the RRP from 40 to 140 granules and a decrease in tau for the refilling of the RRP from 31 to 19 s. 4. Collectively, the effects of ACh on the RRP and tau result in a > 10-fold stimulation of the rate at which granules are supplied for release.

Keywords

  • Physiology

Other

Published
  • Islet patophysiology
  • Islet cell exocytosis
  • Islet cell physiology
  • ISSN: 1469-7793
Erik Renström
E-mail: erik [dot] renstrom [at] med [dot] lu [dot] 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

33

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