Characterization of TRPM8-Like Channels Activated by the Cooling Agent Icilin in the Macrophage Cell Line RAW 264.7

Characterization of TRPM8-Like Channels Activated by the Cooling Agent Icilin in the Macrophage... Icilin is recognized as a chemical agonist of nociceptors and can activate TRPM8 channels. However, whether this agent has any effects on immune cells remains unknown. In this study, the effects of icilin on ion currents were investigated in RAW 264.7 murine macrophage-like cells. Icilin (1–100 μM) increased the amplitude of nonselective (NS) cation current (I NS) in a concentration-dependent manner with an EC50 value of 8.6 μM. LaCl3 (100 μM) or capsazepine (30 μM) reversed icilin-induced I NS; however, neither apamin (200 nM) nor iberiotoxin (200 nM) had any effects on it. In cell-attached configuration, when the electrode was filled with icilin (30 μM), a unique population of NS cation channels were activated with single-channel conductance of 158 pS. With the use of a long-lasting ramp pulse protocol, increasing icilin concentration produced a left shift in the activation curve of NS channels, with no change in the slope factor of the curve. The probability of channel opening enhanced by icilin was increased by either elevated extracellular Ca2+ or application of ionomycin (10 μM), while it was reduced by BAPTA-AM (10 μM). Icilin-stimulated activity is associated with an increase in mean open time and a reduction in mean closed time. Under current-clamp conditions, icilin caused membrane depolarization. Therefore, icilin interacts with the TRPM8-like channel to increase I NS and depolarizes the membrane in these cells. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Characterization of TRPM8-Like Channels Activated by the Cooling Agent Icilin in the Macrophage Cell Line RAW 264.7

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Publisher
Springer-Verlag
Copyright
Copyright © 2011 by Springer Science+Business Media, LLC
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-011-9358-6
Publisher site
See Article on Publisher Site

Abstract

Icilin is recognized as a chemical agonist of nociceptors and can activate TRPM8 channels. However, whether this agent has any effects on immune cells remains unknown. In this study, the effects of icilin on ion currents were investigated in RAW 264.7 murine macrophage-like cells. Icilin (1–100 μM) increased the amplitude of nonselective (NS) cation current (I NS) in a concentration-dependent manner with an EC50 value of 8.6 μM. LaCl3 (100 μM) or capsazepine (30 μM) reversed icilin-induced I NS; however, neither apamin (200 nM) nor iberiotoxin (200 nM) had any effects on it. In cell-attached configuration, when the electrode was filled with icilin (30 μM), a unique population of NS cation channels were activated with single-channel conductance of 158 pS. With the use of a long-lasting ramp pulse protocol, increasing icilin concentration produced a left shift in the activation curve of NS channels, with no change in the slope factor of the curve. The probability of channel opening enhanced by icilin was increased by either elevated extracellular Ca2+ or application of ionomycin (10 μM), while it was reduced by BAPTA-AM (10 μM). Icilin-stimulated activity is associated with an increase in mean open time and a reduction in mean closed time. Under current-clamp conditions, icilin caused membrane depolarization. Therefore, icilin interacts with the TRPM8-like channel to increase I NS and depolarizes the membrane in these cells.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Mar 29, 2011

References

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