Measurement and modeling of Ca2+ waves in isolated rabbit ventricular cardiomyocytes

N. MacQuaide, J. Dempster, G. L. Smith*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The time course and magnitude of the Ca(2+) fluxes underlying spontaneous Ca(2+) waves in single permeabilized ventricular cardiomyocytes were derived from confocal Fluo-5F fluorescence signals. Peak flux rates via the sarcoplasmic reticulum (SR) release channel (RyR2) and the SR Ca(2+) ATPase (SERCA) were not constant across a range of cellular [Ca(2+)] values. The Ca(2+) affinity (K(mf)) and maximum turnover rate (V(max)) of SERCA and the peak permeability of the RyR2-mediated Ca(2+) release pathway increased at higher cellular [Ca(2+)] loads. This information was used to create a computational model of the Ca(2+) wave, which predicted the time course and frequency dependence of Ca(2+) waves over a range of cellular Ca(2+) loads. Incubation of cardiomyocytes with the Ca(2+) calmodulin (CaM) kinase inhibitor autocamtide-2-related inhibitory peptide (300 nM, 30 mins) significantly reduced the frequency of the Ca(2+) waves at high Ca(2+) loads. Analysis of the Ca(2+) fluxes suggests that inhibition of CaM kinase prevented the increases in SERCA V(max) and peak RyR2 release flux observed at high cellular [Ca(2+)]. These data support the view that modification of activity of SERCA and RyR2 via a CaM kinase sensitive process occurs at higher cellular Ca(2+) loads to increase the maximum frequency of spontaneous Ca(2+) waves.

Original languageEnglish
Pages (from-to)2581-2595
Number of pages15
JournalBiophysical Journal
Volume93
Issue number7
DOIs
Publication statusPublished - 1 Oct 2007

Keywords

  • Animals
  • Calcium/metabolism
  • Calmodulin/metabolism
  • Computer Simulation
  • Fluorescent Dyes/pharmacology
  • Kinetics
  • Models, Biological
  • Muscle Cells/metabolism
  • Myocardium/metabolism
  • Myocytes, Cardiac/metabolism
  • Rabbits
  • Ryanodine Receptor Calcium Release Channel/metabolism
  • Sarcoplasmic Reticulum/metabolism
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism

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