Assessing Ca²⁺-removal pathways in cardiac myocytes

Virginie Bito, Karin R. Sipido*, Niall Macquaide

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The decline of an intracellular calcium ([Ca(2+)]i) transient during a single excitation-contraction coupling (ECC) cycle reflects the combined activity of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) pump and the sarcolemmal Na(+)-Ca(2+) exchanger (NCX), along with minor contributions of the plasma membrane Ca(2+)-ATPase and mitochondrial Ca(2+) uniporter, in removing Ca(2+) from the cytosol. A traditional approach for assessing the individual components is to fit the decline of the [Ca(2+)]i transient evoked during electrical stimulation with an exponential. This reflects mostly the SERCA-dependent rate of uptake, which can be properly deduced after correcting for a component of NCX removal. As NCX function is an important determinant of the membrane potential as well as the Ca(2+) balance, we present here several detailed protocols for assessing NCX function. As the reversal potential and the amplitudes of the current are highly dependent on the prevailing concentrations of Na(+) and Ca(2+), we show how NCX function can be assessed under highly controlled conditions, with Ca(2+) and Na(+) clamped, as well as under more physiological conditions, with freely changing Ca(2+) and Na(+).

Original languageEnglish
Pages (from-to)498-503
Number of pages6
JournalCold Spring Harbor protocols
Issue number5
Publication statusPublished - 1 May 2015


  • Calcium/analysis
  • Cytological Techniques/methods
  • Electrophysiological Phenomena
  • Metabolic Networks and Pathways
  • Myocytes, Cardiac/chemistry


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