QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by KERRY, C. J. Articles by WASHIO, H. Search for Related Content PubMed Articles by KERRY, C. J. Articles by WASHIO, H.

Journal of Experimental Biology 127,121-134 (1987)
Published by Company of Biologists 1987

Single-Channel Studies of the Action of (+)-Tubocurarine on Locust Muscle Glutamate Receptors

C. J. KERRY ¹, R. L. RAMSEY ¹, M. S. P. SANSOM ¹, P. N. R. USHERWOOD ¹, and H. WASHIO ²

¹ Department of Zoology, University of Nottingham, University Park, Nottingham NG7 2RD, UK
² Department of Zoology, University of Nottingham, University Park, Nottingham NG7 2RD, UK; SERC senior visiting fellow. Present address: Laboratory of Neurophysiology, Mitsubishi-Kasei Institute of Life Sciences, Machida-Shi, Tokyo 194, Japan.

The effects of (+)-tubocurarine (TC) on single glutamate-activated channels in voltage-clamped locust muscle fibres have been examined using the patch-clamp technique. Glutamate alone produced a concentration-dependent increase in the probability of the channel being in the open state (p_o), but an increase in the concentration of glutamate (5x10^-5-5x10^-3 moll^-1) in the presence of 5x10^-4 moll^-1 TC left p_o essentially unchanged. TC (5x10^-6-5x10^-4moll^-1) caused a concentration- dependent decrease in the mean open time and in p_o for channels opened by 10^-4 moll^-4 glutamate. Correlations between successive openings and successive closings, which are characteristic of the kinetics of the muscle glutamate-receptorgated channel of locust muscle, were weakened in the presence of TC. There was little evidence of voltage sensitivity of TC action over the limited membrane potential (V_m) range -70 to -120 mV. The results are consistent with the idea that TC blocks the cation-selective channel gated by glutamate receptors in insect muscle and that the unblocking rate is low. They suggest also that block is at the level of the open channel, a conclusion supported by the wholly activation-induced depression of the neurally evoked twitch contraction of locust muscle by TC. Based upon a simple model for open channel block, TC is estimated to have a dissociation constant of 1.57 µmoll^-1 (V_m = -100mV). The rate of association of blocker with channel is estimated to be 8.74x10^-3ms^-1(moll^-1)^-1 (V_m=-100mV). The rate of dissociation, estimated indirectly from the single-channel data, is 1.53x10^-2ms^-1, which gives a mean channel block time of 65.4 ms.

Key words: (+)-tubocurarine, l-glutamate, locust muscle, open channel block

Accepted on August 22, 1986

This article has been cited by other articles:

				D. Janssen, C. Derst, R. Buckinx, J. Van den Eynden, J.-M. Rigo, and E. Van Kerkhove Dorsal Unpaired Median Neurons of Locusta migratoria Express Ivermectin- and Fipronil-Sensitive Glutamate-Gated Chloride Channels J Neurophysiol, April 1, 2007; 97(4): 2642 - 2650. [Abstract] [Full Text] [PDF]