The role of reduced potassium conductance in generating triggered activity in guinea-pig ventricular muscle

Eran Gilat, Charles W. Nordin, Ronald S. Aronson

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

This study investigates the role of reducing potassium conductance (gK) in generating delayed afterdepolarizations and triggered activity in small preparations of ventricular muscle from guinea-pig hearts. We used agents believed to reduce gK (low or absent K0, tetraethylammonium (TEA), CsCl) and we used ouabain (10-6 m) to induce delayed afterdepolarizations. Treatment with ouabain only caused subthreshold delayed afterdepolarizations or occasionally non-sustained triggered activity. Exposure to Tyrode's solution with K reduced from 4 to 2 mm or K-free Tyrode's solution, with or without ouabain, caused subthreshold delayed afterdepolarizations and sometimes non-sustained triggered activity. Exposure to Tyrode's solution containing TEA and ouabain caused sustained triggered activity, supporting the hypothesis that accumulation of extracellular K inhibits the development of triggered activity. Presumably, the reduction in gK caused by TEA is not reversed by accumulation of extracellular K so that the delayed afterdepolarizations in the presence of persistently reduced gK are large enough to induced sustained triggered activity. Under extreme conditions, when Cs replaced K and half the NaCl was replaced by TEA, delayed afterdepolarizations occurred in the presence of markedly reduced gK, the result being the rapid development of sustained triggered activity, even at the basic drive rate of 1 Hz. Our results suggest that reduced gK plays an important role in the development of triggered activity.

Original languageEnglish (US)
Pages (from-to)619-628
Number of pages10
JournalJournal of Molecular and Cellular Cardiology
Volume22
Issue number5
DOIs
StatePublished - May 1990

Keywords

  • Delayed afterdepolarizations
  • Membrane conductance
  • Potassium conductance
  • Triggered activity
  • Ventricular muscle

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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