HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Correction (v489,p925) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed 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 Wall, M J Articles by Dale, N Search for Related Content PubMed PubMed Citation Articles by Wall, M J Articles by Dale, N

School of Biological Sciences, University of Bristol, UK.

1. Acutely isolated Xenopus spinal neurons possess a slowly activating Ca(2+)-dependent outward current which was revealed either by removal of external Ca2+ or by the addition of the Ca2+ channel blocker, 150 microM Cd2+. 2. The Ca(2+)-sensitive current was very slow to activate and had a mean time constant of activation of 437 ms at 0 mV. The current also had very long tail currents which were blocked by Cd2+. The rate of decay of the slowest component of the Ca(2+)-dependent tail currents was insensitive to membrane potential suggesting that the relaxation of the Ca(2+)-dependent current may only be weakly voltage dependent. 3. The reversal potential of the Ca(2+)-sensitive tail currents depended on the concentration of external K+ in a manner predicted by the Nernst equation. Thus the Ca(2+)-sensitive current was carried by K+. 4. The toxin apamin (10 nM to 2 microM) selectively blocked the Ca(2+)-dependent K+ current without affecting voltage-gated K+ currents. This current may be analogous to a small-conductance Ca(2+)-dependent K+ (SK) current; however, unlike some SK currents, the Ca(2+)-dependent K+ current was also sensitive to 500 microM tetraethylammonium chloride (TEA). 5. Applications of 10 nM apamin to spinalized embryos did not perturb the motor pattern for swimming. However, the cycle periods over which the locomotor rhythm generator could generate appropriate motor activity were lengthened by about 10% and the mean duration of swimming episodes was increased by approximately 40%. 6. We therefore propose that the Ca(2+)-dependent K+ current plays an important role in the self-termination of motor activity.

This article has been cited by other articles:

				W.-C. Li, B. Sautois, A. Roberts, and S. R. Soffe Reconfiguration of a Vertebrate Motor Network: Specific Neuron Recruitment and Context-Dependent Synaptic Plasticity J. Neurosci., November 7, 2007; 27(45): 12267 - 12276. [Abstract] [Full Text] [PDF]