ATP Regulates Sodium Channel Kinetics in Pancreatic Islet Beta Cells

ATP Regulates Sodium Channel Kinetics in Pancreatic Islet Beta Cells Pancreatic beta cells act as glucose sensors, in which intracellular ATP ([ATP]i) are altered with glucose concentration change. The characterization of voltage-gated sodium channels under different [ATP]i remains unclear. Here, we demonstrated that increasing [ATP]i within a certain range of concentrations (2–8 mM) significantly enhanced the voltage-gated sodium channel currents, compared with 2 mM cytosolic ATP. This enhancement was attenuated by even high intracellular ATP (12 mM). Furthermore, elevated ATP modulated the sodium channel kinetics in a dose-dependent manner. Increased [ATP]i shifted both the current–voltage curve and the voltage-dependent inactivation curve of sodium channel to the right. Finally, the sodium channel recovery from inactivation was significantly faster when the intracellular ATP level was increased, especially in 8 mM [ATP]i, which is an attainable concentration by the high glucose stimulation. In summary, our data suggested that elevated cytosolic ATP enhanced the activity of Na+ channels, which may play essential roles in modulating β cell excitability and insulin release when blood glucose concentration increases. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

ATP Regulates Sodium Channel Kinetics in Pancreatic Islet Beta Cells

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Publisher
Springer-Verlag
Copyright
Copyright © 2013 by Springer Science+Business Media New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-012-9506-7
Publisher site
See Article on Publisher Site

Abstract

Pancreatic beta cells act as glucose sensors, in which intracellular ATP ([ATP]i) are altered with glucose concentration change. The characterization of voltage-gated sodium channels under different [ATP]i remains unclear. Here, we demonstrated that increasing [ATP]i within a certain range of concentrations (2–8 mM) significantly enhanced the voltage-gated sodium channel currents, compared with 2 mM cytosolic ATP. This enhancement was attenuated by even high intracellular ATP (12 mM). Furthermore, elevated ATP modulated the sodium channel kinetics in a dose-dependent manner. Increased [ATP]i shifted both the current–voltage curve and the voltage-dependent inactivation curve of sodium channel to the right. Finally, the sodium channel recovery from inactivation was significantly faster when the intracellular ATP level was increased, especially in 8 mM [ATP]i, which is an attainable concentration by the high glucose stimulation. In summary, our data suggested that elevated cytosolic ATP enhanced the activity of Na+ channels, which may play essential roles in modulating β cell excitability and insulin release when blood glucose concentration increases.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 8, 2013

References

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