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This Article Full Text Full Text (PDF) All Versions of this Article: 95/1/76    most recent 00624.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science 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 Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Rodrigues, A. R. A. Articles by Oertel, D. Search for Related Content PubMed PubMed Citation Articles by Rodrigues, A. R. A. Articles by Oertel, D.

Hyperpolarization-Activated Currents Regulate Excitability in Stellate Cells of the Mammalian Ventral Cochlear Nucleus

Department of Physiology, University of Wisconsin, Madison, Wisconsin

Submitted 15 June 2005; accepted in final form 26 September 2005

The differing biophysical properties of neurons the axons of which form the different pathways from the ventral cochlear nucleus (VCN) determine what acoustic information they can convey. T stellate cells, excitatory neurons the axons of which project locally and to the inferior colliculus, and D stellate cells, inhibitory neurons the axons of which project to the ipsi- and contralateral cochlear nuclei, fire tonically when they are depolarized, and, unlike other cell types in the VCN, their firing rates are sensitive to small changes in resting currents. In both types of neurons, the hyperpolarization-activated current (I_h) reversed at –40 mV, was activated at voltages negative to –60 mV, and half-activated at approximately –88 mV; maximum hyperpolarization-activated conductances (g_{h max}) were 19.1 ± 2.3 nS in T and 30.3 ± 2.6 nS in D stellate cells (means ± SE). Activation and deactivation were slower in T than in D stellate cells. In both types of stellate cells, 50 µM 4(N-ethyl-N-phenylamino)1,2-dimethyl-6-(methylamino) pyridinium chloride (ZD7288) and 2 mM Cs⁺ blocked a 6- to 10-fold greater conductance than the voltage-dependent g_h determined from Boltzmann analyses at –62 mV. The voltage-insensitive, ZD7288-sensitive conductance was proportional to g_{h max} and g_input. 8-Br-cAMP shifted the voltage dependence of I_h in the depolarizing direction, increased the rate of activation, and slowed its deactivation in both T and D stellate cells. Reduction in temperature did not change the voltage dependence but reduced the maximal g_h with a Q₁₀ of 1.3 and slowed the kinetics with a Q₁₀ of 3.3.

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