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Medizin - Open Access LMU - Teil 09/22 Podcast
Sodium channel inactivation kinetics of rat sensory and motor nerve fibres and their modulation by glutathione

Sodium channel inactivation kinetics of rat sensory and motor nerve fibres and their modulation by glutathione

Medizin - Open Access LMU - Teil 09/22 vor 33 Jahren

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Na+ channel currents of rat motor and sensory nerve fibres were
studied with the patch-clamp technique on enzymatically
demyelinated axons. Differences between motor and sensory fibres in
multi-channel inactivation kinetics and the gating of late
single-channel currents were investigated. In the axon-attached
mode, inactivation of multi-channel Na+ currents in sensory axons
was best fitted with a single time constant while for motor axons
two time constants were needed. Late single-channel currents in
sensory axons were characterized by short openings whereas motor
axons exhibited additional long single-channel openings. In
contrast, in excised, inside-out membrane patches, no differences
between motor and sensory fibres were found: in both types of fibre
inactivation of multi-channel Na+ currents proceeded with two time
constants and late single-channel currents showed short and long
openings. After application of the reducing agent glutathione to
the cytoplasmic side of excised inside-out patches, inactivation of
Na+ currents in both motor and sensory fibres proceeded with a
single, fast exponential time constant and late currents appeared
with short openings only. These data indicate that the axonal
metabolism may contribute to the different inactivation kinetics of
Na+ currents in motor and sensory nerve fibres.