Chen Su1,2,
Wu Shui-cai1,
Zeng Yi1,
Liu Xiang-ming2 
1College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124;
2College of Biomedical Engineering, South-Central of University for Nationalities, Hubei, Wuhan, 430074, China.
For correspondence:- Liu Xiang-ming
Email: liu.xiangming@263.net Tel:+8602767843892
Received: 13 August 2012
Accepted: 25 April 2013
Published: 12 June 2013
Citation:
Su C, Shui-cai W, Yi Z, Xiang-ming L.
Differences in Mode of Action of Cochinchinenin A and B on Tetrodotoxin-Resistant Sodium Channels. Trop J Pharm Res 2013; 12(3):385-391
doi:
10.4314/tjpr.v12i3.17
© 2013 The authors.
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Abstract
Purpose: To explore the mechanism of antagonistic interaction between cochinchinenin A and B in modulating tetrodotoxin-resistant (TTR-X) sodium currents.
Methods: The time variation of the effects induced by cochinchinenin A and B on the TTX-R sodium currents in dorsal root ganglion (DRG) neurons of rats were observed using whole-cell patch clamp technique. Based on pharmacological fundamental theory, the modes of action of cochinchinenin A and B on TTX-R channels were distinguished.
Results: The scatter diagram which reflected the time variation of inhibition effect on TTX-R sodium currents induced by cochinchinenin A fitted well with occupancy theory equation (goodness of fit test, p > 0.05), while that of cochinchinenin B fitted well with rate theory equation (p > 0.05). The rate constants for combination and dissociation between cochinchinenin A and TTX-R sodium channel were (198.7 ± 39.9) x 10-3 and (41.1 ± 6.2) x 10-3 respectively; while corresponding values for combination and association between cochinchinenin B and TTX-R sodium channel were (99.9 ± 16.8) x 10-3 and (5.3 ± 0.4) x 10-3 respectively.
Conclusion: The main cause of the antagonistic interaction between cochinchinenin A and B may be attributed to the different modes of their action on TTX-R sodium channels.
Keywords: Cochinchinenin, Tetrodotoxin-resistant sodium channel, Antagonistic interaction, Occupancy theory, Rate theory
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