Comparing the effects of chemical Ca2+ dyes and R-GECO on contractility and Ca2+ transients in adult and human iPSC cardiomyocytes

J Mol Cell Cardiol. 2023 Jul:180:44-57. doi: 10.1016/j.yjmcc.2023.04.008. Epub 2023 Apr 29.

Abstract

We compared commonly used BAPTA-derived chemical Ca2+ dyes (fura2, Fluo-4, and Rhod-2) with a newer genetically encoded indicator (R-GECO) in single cell models of the heart. We assessed their performance and effects on cardiomyocyte contractility, determining fluorescent signal-to-noise ratios and sarcomere shortening in primary ventricular myocytes from adult mouse and guinea pig, and in human iPSC-derived cardiomyocytes. Chemical Ca2+ dyes displayed dose-dependent contractile impairment in all cell types, and we observed a negative correlation between contraction and fluorescence signal-to-noise ratio, particularly for fura2 and Fluo-4. R-GECO had no effect on sarcomere shortening. BAPTA-based dyes, but not R-GECO, inhibited in vitro acto-myosin ATPase activity. The presence of fura2 accentuated or diminished changes in contractility and Ca2+ handling caused by small molecule modulators of contractility and intracellular ionic homeostasis (mavacamten, levosimendan, and flecainide), but this was not observed when using R-GECO in adult guinea pig left ventricular cardiomyocytes. Ca2+ handling studies are necessary for cardiotoxicity assessments of small molecules intended for clinical use. Caution should be exercised when interpreting small molecule studies assessing contractile effects and Ca2+ transients derived from BAPTA-like chemical Ca2+ dyes in cellular assays, a common platform for cardiac toxicology testing and mechanistic investigation of cardiac disease physiology and treatment.

Keywords: Ca2+ handling; Ca2+ indicators; Cardiomyocyte; Contractility; RGECO.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Coloring Agents / metabolism
  • Coloring Agents / pharmacology
  • Guinea Pigs
  • Humans
  • Induced Pluripotent Stem Cells* / metabolism
  • Mice
  • Myocardial Contraction
  • Myocytes, Cardiac* / metabolism
  • Swine

Substances

  • 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
  • Calcium
  • Coloring Agents
  • Fluo 4