Fluorescence Discrimination of Pharmacological Effects on the Na+-Ca2+ Exchanger and Sarco-Endoplasmic Reticulum Ca2+-ATPase in Mouse Ventricular Cardiomyocytes

We developed a method to evaluate the activity of the Na+-Ca2+ exchanger (NCX) and sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) with fluorescence microscopy in mouse ventricular cardiomyocytes. In non-beating ventricular cardiomyocytes, alpha-adrenoceptor stimulation by phenylephrine caused a decrease in the cytoplasmic Ca2+ concentration, which was inhibited by SEA0400, an NCX inhibitor, but not cyclopiazonic acid, a SERCA inhibitor. beta-Adrenoceptor stimulation by isoprenaline caused a decrease in the cytoplasmic Ca2+ concentration, which was inhibited by cyclopiazonic acid but not SEA0400. Ellagic acid, a phenolic phytochemical, also decreased the basal Ca' concentration, which was inhibited by cyclopiazonic acid, but not SEA0400. Thus, this method using fluorescent microscopy and specific inhibitors would be useful for the evaluation of pharmacological agents acting on NCX and SERCA.

Automated summary

A method using fluorescence microscopy and specific inhibitors was developed to evaluate the activity of NCX and SERCA in mouse ventricular cardiomyocytes. Different adrenoceptor stimulations and inhibitors exhibited distinct effects on cytoplasmic Ca2+ concentration in non-beating ventricular cardiomyocytes, suggesting potential applications for pharmacological evaluations targeting NCX and SERCA.