KB-R7943 (No.7943) is a selective inhibitor of Na+/Ca2+ exchanger (NCX), 3-fold more inhibitory to NCX3 than to NCX1 or NCX2.
KB-R7943 inhibits Na+i-dependent Ca2+ uptake and Na+i-dependent [Ca2+]i increase in cardiomyocytes, smooth muscle cells, and NCX1-transfected fibroblasts with IC50 of 1.2-2.4 uM.
KB-R7943 is much less potent in inhibiting Na+o-dependent Ca2+ efflux and Na+o-induced [Ca2+]i decline (IC50>30 uM).
KB-R7943 inhibited Na+i-dependent Ca2+ uptake and Na+o-dependent Ca2+ efflux in n cardiac sarcolemmal preparations with IC50 of 5.4-13 uM.
KB-R7943 markedly inhibited Ca2+ overloading into cardiomyocytes under the Ca2+ paradox conditions.
