Potassium and the excitability properties of normal human motor axons in vivo.

Boërio, Delphine; Bostock, Hugh; Spescha, Romana; Z'Graggen, Werner Josef (2014). Potassium and the excitability properties of normal human motor axons in vivo. PLoS ONE, 9(6), e98262. Public Library of Science 10.1371/journal.pone.0098262

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Hyperkalemia is an important cause of membrane depolarization in renal failure. A recent theoretical model of axonal excitability explains the effects of potassium on threshold electrotonus, but predicts changes in superexcitability in the opposite direction to those observed. To resolve this contradiction we assessed the relationship between serum potassium and motor axon excitability properties in 38 volunteers with normal potassium levels. Most threshold electrotonus measures were strongly correlated with potassium, and superexcitability decreased at higher potassium levels (P = 0.016), contrary to the existing model. Improved modelling of potassium effects was achieved by making the potassium currents obey the constant-field theory, and by making the potassium permeabilities proportional to external potassium, as has been observed in vitro. This new model also accounted well for the changes in superexcitability and other excitability measures previously reported in renal failure. These results demonstrate the importance of taking potassium levels into account when assessing axonal membrane dysfunction by excitability testing, and provide evidence that potassium currents are activated by external potassium in vivo.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology

UniBE Contributor:

Boërio, Delphine; Bostock, Hugh and Z'Graggen, Werner Josef

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Valentina Rossetti

Date Deposited:

18 Feb 2015 15:25

Last Modified:

18 Feb 2015 15:25

Publisher DOI:

10.1371/journal.pone.0098262

PubMed ID:

24893161

BORIS DOI:

10.7892/boris.63395

URI:

https://boris.unibe.ch/id/eprint/63395

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