Veratridine-induced oscillations in membrane potential of cultured rat skeletal muscle: Role of the Na-K pump

Chaya Brodie, S. R. Sampson

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

1. The acute effects of veratridine on membrane potential (Em) and Na-K pump activity in cultured skeletal muscle were examined. 2. At a concentration of 10-4M, veratridine caused depolarization of Em and a decrease in Na-K pump activity. At concentrations of 10-5 and 10-6M, veratridine caused oscillations of Em and an increase in Na-K pump activity compared to untreated, control cells. The oscillations consisted of depolarization to about -40 mV followed by hyperpolarization to about -90 mV; the level of hyperpolarization was higher at 37 than at 23°C. 3. Veratridine-induced oscillations could be prevented by pretreatment with tetrodotoxin (10-6M) and blocked or prevented by ouabain, which depolarizes Em of cultured myotubes. In contrast, depolarization of Em to -60 mV by excess K+ did not alter the amplitude or frequency of the oscillations. 4. The results demonstrate that veratridine-induced increase in Na influx both depolarizes cultured myotubes and increases the activity of the Na-K pump, which repolarizes Em to levels higher than control. This sequence accounts for veratridine-induced oscillations in Em. High concentrations of veratridine cause only depolarization of Em and inhibition of Na-K pump activity.

Original languageEnglish
Pages (from-to)217-226
Number of pages10
JournalCellular and Molecular Neurobiology
Volume10
Issue number2
DOIs
StatePublished - Jun 1990

Keywords

  • Na-K pump
  • Rb uptake
  • electrogenic Na-K pump
  • membrane potential
  • veratridine

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