Abstract
A transient K+ current in cultured olfactory bulb neurons of Xenopus tadpoles was studied using the whole-cell patch-clamp technique. The current, which was resistant to 80 mM tetraethylammoniumchloride (TEA) and 10 nM charybdotoxin but blocked by 5 mM 4-aminopyridine (4-AP), activated between −60 and −4C mV and showed time-and voltage-dependent inactivation. Its peak amplitude was nearly independent of the extracellular K+ concentration ([K+]o) in the range of 0.05 to 10 mM, indicating that its conductance increased upor increasing [K+]o. The transient K+ current showed a slow recovery from inactivation with the time for half-maximum recovery from a conditioning pulse to 80 mV for 1 s varying from 100 ms to 500 ms. Complete recovery required as much as 5–10 s at −80 mV, but could be speed-ed up at hyperpolarized potentials. The current resemble; the RCK4 (Kv1.4) current of rat neurons except that it; recovery from inactivation was independent of [K+]o. High-freqency stimulation (20–67 Hz) of the neurons with short (5 ms) voltage pulses resulted in a frequency-dependent, progressive inactivation of the transient K+ current. This suggests that, during phasic responses of ol-factory bulb neurons, inactivation of the transient K+ current occurs and may lead to lengthening of action potentials and facilitation of synaptic transmission.
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Engel, J., Rabba, J. & Schild, D. A transient, RCK4-like K+ current in cultured Xenopus olfactory bulb neurons. Pflügers Arch. 432, 845–852 (1996). https://doi.org/10.1007/s004240050207
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DOI: https://doi.org/10.1007/s004240050207