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Ca2+ signaling in the pancreatic acinus
1Research and Development, Yanaihara Institute, Inc., Shizuoka, Japan.
Pancreas
|April 21, 1998
Summary
Calcium ion (Ca2+) signaling is crucial for pancreatic acinar cell secretion. Cholecystokinin-8 (CCK-8) triggers recurrent calcium spikes, initiating a sustained secretory response. This study reveals the spatiotemporal dynamics of these calcium signals.
Area of Science:
- Cellular Biology
- Physiology
- Biochemistry
Background:
- Cytosolic free calcium ion concentration ([Ca2+]c) is a key intracellular signal in stimulus-secretion coupling.
- Pancreatic acinar cells utilize [Ca2+]c dynamics for regulated secretion.
Purpose of the Study:
- To investigate the spatiotemporal dynamics of [Ca2+]c in pancreatic acinar cells during cholecystokinin-8 (CCK-8) stimulation.
- To elucidate the role of recurrent calcium spiking in CCK-8-induced secretion.
Main Methods:
- Ratiometric imaging using UV-laser scanning confocal microscopy to monitor [Ca2+]c dynamics.
- Continuous stimulation with physiological concentrations of CCK-8.
Main Results:
- CCK-8 induced recurrent [Ca2+]c spiking, initiating at the basolateral margin and propagating to the luminal margin of acinar cells.
- Calcium signaling was found to be asynchronous across neighboring cells within an acinus.
- A model was proposed where CCK-8 activates Gq-coupled receptors, leading to InsP3 production and recurrent [Ca2+]c spiking.
Conclusions:
- Recurrent [Ca2+]c spiking is a critical mechanism for sustained pancreatic secretion.
- The asynchronous nature of calcium signaling in acinar cells influences the overall secretory response.
- This signaling pathway involves CCK receptor activation, Gq protein coupling, and InsP3-mediated calcium release.