Author's present address E. Renström, L. Eliasson and P. Rorsman: Department of Physiology and Neuroscience, Solvegatan 19, S-22362 Lund, Sweden.
Protein kinase A-dependent and -independent stimulation of exocytosis by cAMP in mouse pancreatic B-cells
Article first published online: 30 SEP 2004
The Journal of Physiology
Volume 502, Issue 1, pages 105–118, July 1997
How to Cite
Renström, E., Eliasson, L. and Rorsman, P. (1997), Protein kinase A-dependent and -independent stimulation of exocytosis by cAMP in mouse pancreatic B-cells. The Journal of Physiology, 502: 105–118. doi: 10.1111/j.1469-7793.1997.105bl.x
Author's email address E. Renstrom: firstname.lastname@example.org
- Issue published online: 30 SEP 2004
- Article first published online: 30 SEP 2004
- Received 28 November 1996; accepted 7 April 1997.
- 1The mechanisms by which cAMP stimulates Ca2+-dependent insulin secretion were investigated by combining measurements of whole-cell Ca2+ currents, the cytoplasmic free Ca2+ concentration ([Ca2+]i) and membrane capacitance in single mouse B-cells maintained in tissue culture.
- 2Cyclic AMP stimulated exocytosis > 4-fold in whole-cell experiments in which secretion was evoked by intracellular dialysis with a Ca2+-EGTA buffer with a [Ca2+]i of 1.5μm. This effect was antagonized by inhibitors of protein kinase A (PKA).
- 3Photorelease of cAMP from a caged precursor potentiated exocytosis at Ca2+ concentrations which were themselves stimulatory (60 nm), but was without effect in the complete absence of Ca2+.
- 4Elevation of intracellular cAMP (by exposure to forskolin) evoked a 6-fold PKA-dependent enhancement of the maximal exocytotic response (determined as the maximum increase in cell capacitance that could be elicited by a train of depolarizations) in perforated-patch whole-cell recordings.
- 5Exocytosis triggered by single depolarizations in standard whole-cell recordings was strongly potentiated by cAMP, but in this case the effect was unaffected by PKA inhibition.
- 6When exocytosis was triggered by Ca2+ released from Ca2+-NP-EGTA (‘caged Ca2+), cAMP exerted a dual stimulatory effect on secretion: a rapid (initiated within 80 ms) PKA-independent phase and a late PKA-dependent component.
- 7We conclude that cAMP stimulates insulin secretion both by increasing the release probability of secretory granules already in the readily releasable pool and by accelerating the refilling of this pool.