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BSC94
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Literature
38 records
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compatible with modal-gating hypothesis for sodium channels.
dependence of the transient (INa) and persistent (INaP) Na+ currents in
neocortical neurons results from the state of inactivation of one type of Na+
channel rather than from the existence of different types of Na+ channels.
This question was examined in acutely isolated pyramidal neurons from the
sensorimotor cortex of rats by using papain to remove inactivation from INa
and comparing the resulting activation curve with that of INaP. 2. In control
cells, INaP activated at more negative potentials than INa. Inclusion of
papain in the recording pipette removed inactivation from INa and caused the
INa activation curve to be shifted leftward to the position of the curve for
INaP measured in control cells. Papain greatly increased both INa amplitude
and the time to reach peak INa during smaller depolarizations, whereas the
difference between control and test currents was reduced during large
depolarizations. 3. We conclude that differences in the voltage dependence of
INa and INaP activation does not provide sufficient evidence that these
currents flow through separate sets of Na+ channels. Instead, our results are
consistent with the idea that INaP largely arises from a fraction of the
transient Na+ channels that intermittently lose their inactivation.
