Mechanical alternans and restitution in failing SHHF rat left ventricles

Cristian Dumitrescu, Prakash Narayan, Igor R. Efimov, Yuanna Cheng, M. Judith Radin, Sylvia A. McCune, Ruth A. Altschuld*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


We examined mechanical alternans and electromechanical restitution in normal and failing rat hearts. Alternans occurred at 5 Hz in failing versus 9 Hz in control hearts and was reversed by 300 nM isoproterenol, 6 mM extracellular Ca2+, 300 nM-BAY K 8644, or 50 nM ryanodine. Restitution curves comprised phase I, which was completed before relaxation of the steady-state beat, and phase II, which occurred later. Phase I action potential area and developed pressure ratios were significantly reduced in the failing versus control hearts. Phase II was a monoexponential increase in relative developed pressure as the extrasystolic interval was increased. The plateau of phase II was significantly elevated in failing hearts. Thapsigargin (3 μM) plus ryanodine (200 nM) potentiated phase I to a significantly greater extent in control versus failing hearts and abolished phase II in both groups. The results suggest that both regulation of Ca2+ influx across the sarcolemma and Ca2+ release by the sarcoplasmic reticulum may contribute to altered excitation-contraction coupling in the failing spontaneously hypertensive heart failure prone rat heart.

Original languageEnglish (US)
Pages (from-to)H1320-H1326
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number4 51-4
StatePublished - 2002


  • Calcium current facilitation
  • Calmodulin
  • Heart failure
  • Sarcoplasmic reticulum

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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