Anion exchanger 3 is required for sasanquasaponin to inhibit ischemia/reperfusion-induced elevation of intracellular Cl- concentration and to elicit cardioprotection.

Recent studies have shown that the cardioprotection of sasanquasaponin (SQS) against ischemia/reperfusion injury is related to inhibiting ischemia/reperfusion-induced elevation of intracellular Cl(-) concentration (Cl(-) ). However, the mechanism of inhibition remains unclear. Anion exchanger 3 (AE(3)) is an important regulatory protein for Cl(-). This study investigated whether AE(3) plays the critical role in the inhibitory effect of SQS on elevation of Cl(-) induced by ischemia/reperfusion and mediates the cardioprotection of SQS in H9c2 cells. Normal and AE(3) -knockdown H9c2 cells were incubated for 24 h with or without various concentrations of SQS (0.1, 1, or 10 µM) followed by simulated ischemia/reperfusion (sI/R). AE(3) expression was detected by Western blot. Flow cytometer analysis was employed to determine Cl(-) Ca(2+) , reactive oxygen species (ROS) production, and cell apoptosis. The results showed that SQS pretreatment concentration-dependently attenuated sI/R-induced viability loss and lactate dehydrogenase leakage in normal H9c2 cells. Additionally, SQS concentration-dependently up-regulated AE(3) protein expression, and inhibited sI/R-induced the elevation of Cl(-) followed by the attenuation of Ca(2+) overload, ROS production, and cell apoptosis. However, the dose-dependent cardioprotection induced by SQS was abolished in AE(3) -knockdown H9c2 cells, and the inhibitory effects of SQS on Cl(-), Ca(2+) overload, ROS production, and cell apoptosis were also reversed. Our data indicate that AE(3) mediates the cardioprotective effect of SQS against sI/R injury. Importantly, AE(3) is required for SQS to inhibit sI/R-induced elevation of Cl(-), which subsequently inhibited sI/R-induced Ca(2+) overload, ROS production, and cell apoptosis.