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Bidirectional insulin granule turnover in the submembrane space during K(+) depolarization-induced secretion.
- Source :
-
Traffic (Copenhagen, Denmark) [Traffic] 2011 Sep; Vol. 12 (9), pp. 1166-78. Date of Electronic Publication: 2011 Jul 13. - Publication Year :
- 2011
-
Abstract
- Like primary mouse islets, MIN6 pseudoislets responded to the depolarization by 40 mm KCl and the resulting increase in the free cytosolic Ca(2+) concentration ([Ca(2+) ](i) ) with a massive increase in insulin secretion, whereas 15 mm KCl had little effect in spite of a clear increase in [Ca(2+) ](i) . Analysis of insulin-enhanced green fluorescent protein (EGFP)-labeled granules in MIN6 cells by total internal reflection fluorescence (TIRF) microscopy showed that 40 mm KCl increased the number of short-term resident granules (<1 second presence in the submembrane space), while the total granule number and the number of long-term resident granules decreased. The rates of granule arrival at and departure from the submembrane space changed in parallel and were two orders of magnitude higher than the release rates, suggesting a back-and-forth movement of the granules as the primary determinant of the submembrane granule number. The effect of 15 mm KCl resembled that of 40 mm but did not achieve significance. Both 15 and 40 mm KCl evoked a [Ca(2+) ](i) increase, which was antagonized by 10 µm nifedipine. Nifedipine also antagonized the effect on secretion and on granule number and mobility. In conclusion, during KCl depolarization L-type Ca(2+) channels seem to regulate two processes, insulin granule turnover in the submembrane space and granule exocytosis.<br /> (© 2011 John Wiley & Sons A/S.)
- Subjects :
- Animals
Calcium metabolism
Calcium Channel Blockers pharmacology
Calcium Channels, L-Type metabolism
Cell Membrane metabolism
Cells, Cultured
Green Fluorescent Proteins metabolism
Insulin Secretion
Mice
Nifedipine pharmacology
Potassium metabolism
Cytoplasmic Granules metabolism
Exocytosis drug effects
Insulin metabolism
Membrane Potentials drug effects
Potassium Chloride pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 1600-0854
- Volume :
- 12
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Traffic (Copenhagen, Denmark)
- Publication Type :
- Academic Journal
- Accession number :
- 21668594
- Full Text :
- https://doi.org/10.1111/j.1600-0854.2011.01231.x