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, α-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. β-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 Ca2+ 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.