Assessing Ca²⁺-removal pathways in cardiac myocytes

Bito, V., Sipido, K. R. and MacQuaide, N. (2015) Assessing Ca²⁺-removal pathways in cardiac myocytes. Cold Spring Harbor Protocols, 2015(5), pp. 498-503. (doi: 10.1101/pdb.prot076992) (PMID:25934931)

Abstract

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(+).

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacQuaide, Dr Niall
• Authors: Bito, V., Sipido, K. R., and MacQuaide, N.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Cold Spring Harbor Protocols
• Publisher: Cold Spring Harbor Laboratory Press
• ISSN: 1940-3402
• ISSN (Online): 1559-6095