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Journal of Experimental Biology, Vol 203, Issue 20 3189-3198, Copyright © 2000 by Company of Biologists

JOURNAL ARTICLES

K(+) currents in cultured neurones from a polyclad flatworm

SD Buckingham and AN Spencer
Bamfield Marine Station, Bamfield, British Columbia, Canada V0R 1B0. aspencer@bms.bc.ca

Cells from the brain of the polyclad flatworm Notoplana atomata were dispersed and maintained in primary culture for up to 3 weeks. Whole-cell patch-clamp of presumed neurones revealed outwardly directed K(+) currents that comprised, in varying proportions, a rapidly activating (time constant tau =0.94+/-0.79 ms; N=15) and inactivating ( tau =26.1+/-1.9 ms; N=22) current and a second current that also activated rapidly ( tau =1.1+/-0.2 ms; N=9) (means +/- s.e.m.) but did not inactivate within 100 ms. Both current types activated over similar voltage ranges. Activation and steady-state inactivation overlap and are markedly rightward-shifted compared with most Shaker-like currents (half-activation of 16.9+/-1. 9 mV, N=7, half-inactivation of -35.4+/-3.0 mV, N=5). Recovery from inactivation was rapid (50+/-2.5 ms at -90 mV). Both currents were unaffected by tetraethylammonium (25 mmol l(-1)), whereas 4-aminopyridine (10 mmol l(-1)) selectively blocked the inactivating current. The rapidly inactivating current, like cloned K(+) channels from cnidarians and certain cloned K(+) channels from molluscs and the Kv3 family of vertebrate channels, differed from most A-type K(+) currents reported to date. These findings suggest that K(+) currents in Notoplana atomata play novel roles in shaping excitability properties.

This article has been cited by other articles:

				T. L. Klassen, S. D. Buckingham, D. M. Atherton, J. B. Dacks, W. J. Gallin, and A. N. Spencer Atypical Phenotypes From Flatworm Kv3 Channels J Neurophysiol, May 1, 2006; 95(5): 3035 - 3046. [Abstract] [Full Text] [PDF]

				S. D. Buckingham and A. N. Spencer Role of High-Voltage Activated Potassium Currents in High-Frequency Neuronal Firing: Evidence From a Basal Metazoan J Neurophysiol, August 1, 2002; 88(2): 861 - 868. [Abstract] [Full Text] [PDF]