Rate-dependent [K+]o, accumulation in canine right atria in vivo: Electrophysiological consequences

Akira Miyata, Joshua D. Dowell, Douglas P. Zipes, Michael Rubart-von der Lohe

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Sudden increases in heart rate cause accumulation of K+ in the extracellular space. However, the exact relationship between rate and extracellular K+ concentration ([K+]o) in vivo is unknown. We measured [K+]o in right atria of anesthetized dogs by using K+-sensitive electrodes. Peak increase in [K+]o ranged from 0.18 ± 0.04 mM [means ± SE; cycle length (CL) = 350 ms] to 0.80 ± 0.09 mM (CL = 250 ms) above baseline (3.50 ± 0.08 mM at CL = 380 ms; n = 5). During rapid pacing-induced atrial fibrillation, peak increase in [K+]o averaged 0.80 ± 0.07 mM (n = 5). Whole cell current-clamp measurements in single right atrial myocytes (n = 5) showed that raising [K+]o from 3 to 5 mM in 1-mM steps progressively depolarized resting membrane potential and reduced both phase 0 action potential amplitude and maximal upstroke velocity. Multisite epicardial mapping (n = 4) demonstrated that sudden rate increases changed longitudinal conduction velocity (CVL) by -3.6 ± 1.8% to -5.9 ± 1.2% over a CL range of 330 to 250 ms. Our observations suggest that rate-related [K+]o accumulation in vivo is of sufficient magnitude to modulate those cellular electrophysiological properties that determine atrial CVL.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume283
Issue number2 52-2
StatePublished - 2002

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Epicardial Mapping
Extracellular Space
Heart Atria
Membrane Potentials
Atrial Fibrillation
Muscle Cells
Action Potentials
Canidae
Electrodes
Heart Rate
Dogs

Keywords

  • Atrium
  • Fibrillation
  • Potassium
  • Tachycardia

ASJC Scopus subject areas

  • Physiology

Cite this

Rate-dependent [K+]o, accumulation in canine right atria in vivo : Electrophysiological consequences. / Miyata, Akira; Dowell, Joshua D.; Zipes, Douglas P.; Rubart-von der Lohe, Michael.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 283, No. 2 52-2, 2002.

Research output: Contribution to journalArticle

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