Axonal hyperpolarization associated with acute hypokalemia: Multiple excitability measurements as indicators of the membrane potential of human axons

Satoshi Kuwabara, Kazuaki Kanai, Jia Ying Sung, Kazue Ogawara, Takamichi Hattori, David Burke, Hugh Bostock

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

Multiple nerve excitability measurements have been proposed for clinical testing of nerve function, and an important determinant of excitability is membrane potential. We report a patient with acquired hypokalemic paralysis in whom multiple excitability indices (stimulus -response curve, strength-duration properties, threshold electrotonus, recovery cycle) were measured during and after an acute hypokalemic attack (serum K+ level, 2.1 mEq/L and 4.5 mEq/L, respectively). During hypokalemia, there was a shift of the stimulus-response curve to the right, a decrease in strength-duration time constant, a "fanning-out" of responses during threshold electrotonus, a reduction in relative refractory period, and an increase in superexcitability; all of these indicate axonal hyperpolarization, presumably due to the K+ equilibrium potential being more negative. These indices returned to normal 20 h later, associated with normalization of the serum K+ level. These results demonstrate that the changes associated with hypokalemic paralysis are not confined to muscle and that axons undergo hyperpolarization in vivo. Multiple excitability measurements can be used as a tool to identify changes in membrane potential of human axons.

Original languageEnglish
Pages (from-to)283-287
Number of pages5
JournalMuscle and Nerve
Volume26
Issue number2
DOIs
Publication statusPublished - 2002
Externally publishedYes

Keywords

  • Hypokalemia
  • Membrane potential
  • Multiple excitability measurements
  • Refractory period
  • Superexcitability
  • Threshold of electrotonus

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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