TY - JOUR
T1 - Heterogeneous voltage dependence of inward rectifier currents in spiral ganglion neurons
AU - Mo, Zun Li
AU - Davis, Robin L.
PY - 1997/12
Y1 - 1997/12
N2 - Inward rectification was characterized in neonatal spiral ganglion neurons maintained in tissue culture. Whole cell current and voltage-clamp techniques were used to show that the hyperpolarization-activated cationic (I(h)) current underlies most or all of the inward rectification demonstrated in these neurons. The average reversal potential (-41.3 mV) and cesium sensitivity were typical of that found in other neurons and cell types. What was unique about the hyperpolarization-activated currents, however, was that the half-maximal voltages (V( 1/4 )) and slope factors (k) that characterized I(h) current activation were graded from neuron to neuron. Voltage-clamp recordings made with standard bath and pipette solutions revealed V( 1/4 ) values that ranged from -78.1 to -122.1 mV, with slope factors from 7.6 to 13.1. These gradations in the voltage-dependent features of the I(h) current did not result from variability in the recording conditions because independently measured Na+ current-to-voltage relationships were found to be uniform (peak current at -20 mV). Moreover, the range and average V(1/2) and slope values could be altered with activators [8-(4-chlorophenylthio) adenosine 3',5'-cyclic monophosphate in combination with okadaic acid] or inhibitors {N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide} of protein indicating that I(h) current heterogeneity most likely resulted from differential phosphorylation.
AB - Inward rectification was characterized in neonatal spiral ganglion neurons maintained in tissue culture. Whole cell current and voltage-clamp techniques were used to show that the hyperpolarization-activated cationic (I(h)) current underlies most or all of the inward rectification demonstrated in these neurons. The average reversal potential (-41.3 mV) and cesium sensitivity were typical of that found in other neurons and cell types. What was unique about the hyperpolarization-activated currents, however, was that the half-maximal voltages (V( 1/4 )) and slope factors (k) that characterized I(h) current activation were graded from neuron to neuron. Voltage-clamp recordings made with standard bath and pipette solutions revealed V( 1/4 ) values that ranged from -78.1 to -122.1 mV, with slope factors from 7.6 to 13.1. These gradations in the voltage-dependent features of the I(h) current did not result from variability in the recording conditions because independently measured Na+ current-to-voltage relationships were found to be uniform (peak current at -20 mV). Moreover, the range and average V(1/2) and slope values could be altered with activators [8-(4-chlorophenylthio) adenosine 3',5'-cyclic monophosphate in combination with okadaic acid] or inhibitors {N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide} of protein indicating that I(h) current heterogeneity most likely resulted from differential phosphorylation.
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U2 - 10.1152/jn.1997.78.6.3019
DO - 10.1152/jn.1997.78.6.3019
M3 - Article
C2 - 9405521
AN - SCOPUS:0031424373
VL - 78
SP - 3019
EP - 3027
JO - Journal of Neurophysiology
JF - Journal of Neurophysiology
SN - 0022-3077
IS - 6
ER -