AIM: To study the effect of Phe-Arg-Cys-Arg-Ser-Phe-CONH2 (FRCRSFa) on Na+/Ca2+ exchange and its specificity in rat ventricular myocytes. METHODS: Na+/Ca2+ exchange current (INa+/Ca2+) and other currents were measured using whole-cell voltage clamp technique. RESULTS: A concentration-dependent inhibition of hexapeptide FRCRSFa on Na +/Ca2+ exchange was observed in rat ventricular myocytes. IC50 of inward and outward INa+/Ca2+ were 2 and 4 micromol/L, respectively. FRCRSFa 5 micromol/L did not affect L-type Ca2+ current, voltage-gated Na+ current, transient outward K+ current, and inward rectifier K+ current. CONCLUSION: These data indicate that FRCRSFa is an available inhibitor of Na+/Ca2+ exchange with relative selectivity and m ay be valuable for studies of the Na+/Ca2+ exchange in cardiac myocytes.
AIM: To study the effect of Phe-Arg-Cys-Arg-Ser-Phe-CONH2 (FRCRSFa) on Na+/Ca2+ exchange and its specificity in rat ventricular myocytes. METHODS: Na+/Ca2+ exchange current (INa+/Ca2+) and other currents were measured using whole-cell voltage clamp technique. RESULTS: A concentration-dependent inhibition of hexapeptide FRCRSFa on Na +/Ca2+ exchange was observed in rat ventricular myocytes. IC50 of inward and outward INa+/Ca2+ were 2 and 4 micromol/L, respectively. FRCRSFa 5 micromol/L did not affect L-type Ca2+ current, voltage-gated Na+ current, transient outward K+ current, and inward rectifier K+ current. CONCLUSION: These data indicate that FRCRSFa is an available inhibitor of Na+/Ca2+ exchange with relative selectivity and m ay be valuable for studies of the Na+/Ca2+ exchange in cardiac myocytes.