Forefront of Na+/Ca2+ exchanger studies: stoichiometry of cardiac Na+/Ca2+ exchanger; 3:1 or 4:1?
The stoichiometry of the Na+/Ca2+ exchanger (NCX) had been generally accepted as 3 Na+:1 Ca2+. However, recently a challenging stoichiometry of 4:1 was proposed. Therefore, using guinea pig ventricular cells, we re-examined the stoichiometry by measuring the reversal potential of the NCX current and intracellular Ca2+ concentrations under the whole-cell voltage clamp. We confirmed that the stoichiometry of NCX is 3:1 not 4:1. In addition, we explored the possible reasons for obtaining erroneous results of a 4:1 stoichiometry.
Hinata
Masamitsu
M
Department of Pharmacology, School of Medicine, Fukushima Medical University, Japan.
Kimura
Junko
J
D000818:Animals; D002118:Calcium / Q000378:metabolism; D006801:Humans; D009206:Myocardium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*
D019831:Sodium-Calcium Exchanger; D002118:Calcium