ISSN:
1432-2013
Keywords:
Ranvier Node
;
Sodium Channels
;
Surface Charges
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Voltage clamp experiments were performed on myelinated nerve fibres of Rana esculenta. The combined effects of increasing extracellular H+ concentration and lowering the Na+ concentration on sodium currents were studied. The presence of negative charges of two types at the external membrane surface could explain the observed shifts in theI Na-V curves and the reduction ofI Na induced by H+. Accordingly, from the data of shifts of the conductance voltage curves we calculate a density of −1e o/(20 Å)2 for unsepecific charges with an intrinsic pKa=4.3. From the reduction ofI Na induced by H+ we estimate a density of −1e o/Na channel for specific charges with an intrinsic pKa=4.5. Na+ ions would bind to these specific charges when passing through the sodium channels and Na+ transport would be blocked if these groups are protonated.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00586919
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