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Updated: Jun 23, 2026

Imaging Calcium Dynamics in Subpopulations of Mouse Pancreatic Islet Cells
Published on: November 26, 2019
Pattern of rise in subplasma membrane Ca2+ concentration determines type of fusing insulin granules in pancreatic
Mica Ohara-Imaizumi1, Kyota Aoyagi, Yoko Nakamichi
1Department of Biochemistry, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
Abstract:
We simultaneously analyzed insulin granule fusion with insulin fused to green fluorescent protein and the subplasma membrane Ca2+ concentration ([Ca2+](PM)) with the Ca2+ indicator Fura Red in rat beta cells by dual-color total internal reflection fluorescence microscopy. We found that rapid and marked elevation in [Ca2+](PM) caused insulin granule fusion mostly from previously docked granules during the high KCl-evoked release and high glucose-evoked first phase release. In contrast, the slow and sustained elevation in [Ca2+](PM) induced fusion from newcomers translocated from the internal pool during the low KCl-evoked release and glucose-evoked second phase release. These data suggest that the pattern of the [Ca2+](PM) rise directly determines the types of fusing granules.
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