Purified endogenous inhibitor of the Na/Ca exchanger can enhance the cardiomyocytes contractility and calcium transients

Boyman Liron, Hiller Reuben, Shpak Beni, Shpak Chagit, Daniel Khananshvili*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Previous studies have shown that the newly found endogenous inhibitor (NCXIF) of the cardiac Na/Ca exchanger (NCX1) is capable of regulating the muscle strip's contractility and relaxation. Here, the effects of purified NCXIF were tested on single cell shortening-lengthening (by using the IR CCD camera coupled with the two-edge video-detector) and [Ca]i-transients (by monitoring the changes in fluo-3 fluorescence). A perfusion of isolated cardiomyocytes (paced at 0.5-1.0 Hz) with NCXIF results in 4-6-fold enhancement in the amplitude of cell shortening-lengthening reaching the steady-state levels within 5-8 min (n = 20, p < 0.009). Simultaneous recordings of cell shortening-lengthening and [Ca]i-transients from the same cell show that the amplitude enhancement is associated with accelerated decay of both signals. Therefore, the NCXIF-dependent modulation of the single cell contractility is primarily governed by Ca-related mechanisms. The observed data are consistent with a proposal suggesting that the inhibition of NCX1 by NCXIF results in Ca-dependent activation of SERCA (SR Ca ATPase), yielding the accelerated decay of the [Ca]i-transients. The subsequent increase in the SR Ca content may result in enhanced Ca-release reflecting the manifested promotion of [Ca]i-transients. More systematic study is required for confirming this working hypothesis.

Original languageEnglish
Pages (from-to)1100-1107
Number of pages8
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - 4 Aug 2006


FundersFunder number
Israeli Academy of Sciences16.0-424
USA-Israeli Binational Science foundation
Bloom's Syndrome Foundation2003-372


    • Calcium
    • Calcium transient
    • Cardiomyocyte
    • EC-coupling
    • Endogenous inhibitor
    • SERCA
    • Sodium-calcium exchange


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