Diversity of early afterdepolarizations in guinea pig myocytes: Spatial characteristics of intracellular Ca2+ concentration

Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu Takishima

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca2+ concentration ([Ca2+]i). Myocytes were enzymatically isolated from guinea pig ventricles. When fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes (n = 26 from eight hearts) and those with heterogeneous changes (n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥-34mV) than EADs with heterogeneous features (≤-57 mV). These results suggest that EADs have at least two constituents.

Original languageEnglish
Pages (from-to)266-274
Number of pages9
JournalHeart and Vessels
Volume10
Issue number5
DOIs
Publication statusPublished - 1995 Oct 1

Keywords

  • Afterdepolarization
  • Calcium ions
  • Cardiac myocytes

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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