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Tropical Journal of Pharmaceutical Research
Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, Nigeria
ISSN: 1596-5996 EISSN: 1596-5996
Vol. 12, No. 3, 2013, pp. 385-391
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Bioline Code: pr13059
Full paper language: English
Document type: Research Article
Document available free of charge
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Tropical Journal of Pharmaceutical Research, Vol. 12, No. 3, 2013, pp. 385-391
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Differences in Mode of Action of Cochinchinenin A and B on Tetrodotoxin-Resistant Sodium Channels
Su, Chen; Shui-cai, Wu; Yi, Zeng & Xiang-ming, Liu
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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