Author:
Hsiao Chie-Fang,Kaur Gurvinder,Vong Angela,Bawa Harpreet,Chandler Scott H.
Abstract
The function and biophysical properties of low threshold Kv1 current in control of membrane resonance, subthreshold oscillations, and bursting in mesencephalic V neurons (Mes V) were examined in rat brain stem slices (P8–P12) using whole cell current and voltage patch-clamp methods. α-dendrotoxin application, a toxin with high specificity for Kv1.1, 1.2, and 1.6 channels, showed the presence of a low-threshold K+current that activated rapidly around −50 mV and was relatively noninactivating over a 1-s period and had a V1/2max of −36.2 mV. Other toxins, specific for individual channels containing either Kv 1.1, 1.2, or 1.3 α-subunits, were applied individually, or in combination, and showed that Kv1 channels are heteromeric, composed of combinations of subunits. In current-clamp mode, toxin application transformed the high-frequency resonant properties of the membrane into a low-pass filter and concomitantly reduced the frequency of the subthreshold membrane oscillations. During this period, rhythmical bursting was transformed into low-frequency tonic discharge. Interestingly, in a subset of neurons that did not show bursting, low doses of α-dendrotoxin (α-DTX) sufficient to block 50% of the low threshold Kv1 channels induced bursting and increased the resonant peak impedance and subthreshold oscillations, which was replicated with computer simulation. This suggests that a critical balance between inward and outward currents is necessary for bursting. This was replicated with computer simulation. Single cell RT-PCR and immunohistochemical methods confirmed the presence of Kv1.1, 1.2, and 1.6 α-subunits in Mes V neurons. These data indicate that low threshold Kv1 channels are responsible for membrane resonance, contribute to subthreshold oscillations, and are critical for burst generation.
Publisher
American Physiological Society
Subject
Physiology,General Neuroscience
Cited by
29 articles.
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