KB-R7943 (mesylate)

KB-R7943 mesylate is a widely used inhibitor of the reverse Na⁺/Ca²⁺ exchanger (NCX_rev) with IC₅₀ of 5.7±2.1 μM. KB-R7943 mesylate induces cancer cell death via activating the JNK pathway and blocking autophagic flux. IC50 & Target:IC50: 5.7±2.1 μM (Na⁺/Ca²⁺ exchanger)^[1] In Vitro:KB-R7943 mesylate blocks NMDAR-mediated ion currents, and inhibits NMDA-induced increase in cytosolic Ca²⁺ with IC₅₀=13.4±3.6 μM but accelerates calcium deregulation and mitochondrial depolarization in glutamate-treated neurons. KB-R7943 depolarizes mitochondria in a Ca²⁺-independent manner. KB-R7943 inhibits 2,4-dinitrophenol-stimulated respiration of cultured neurons with IC₅₀=11.4±2.4 μM. In addition to NCX_rev, KB-R7943 dose-dependently and reversibly blocked ion currents elicited by NMDA. KB-R7943 dose-dependently inhibits NMDA-induced increases in [Ca²⁺]_c with IC₅₀=13.4±3.6 μM confirming the inhibition of NMDA receptors observed in electrophysiological experiments^[1]. _wtRyR1-HEK 293 pretreated with KB-R7943 (10 μM, 10 min) dissolved in the bulk perfusion exhibited significantly attenuated responses to caffeine. In this regard, KB-R7943 produced more pronounced inhibition of caffeine-induced Ca²⁺ release elicited by 1 mM compared with 0.5 and 0.75 mM (60 versus 58 versus 37%, p<0.05, respectively)^[2]. KB-R7943 inhibits both I_hERG and native I_Kr rapidly on membrane depolarization with IC₅₀ values of ~89 and ~120 nM, respectively, for current tails at ?40 mV following depolarizing voltage commands to +20 mV. I_hERG inhibition by KB-R7943 exhibits both time- and voltage-dependence but shows no preference for inactivated over activated channels^[3].