In isolated rat hearts subjected to ischaemia/reperfusion, NHE-1 inhibition with AVE-4890 reduced mitochondrial PTP opening by 28% (P < 0.05) and improved postischaemic recovery.
Does NHE-1 inhibition with AVE-4890 reduce mitochondrial PTP opening and apoptosis in rat hearts subjected to ischemia/reperfusion?
NHE-1 inhibition with AVE-4890 attenuates mitochondrial PTP opening and apoptosis in rat hearts subjected to ischemia/reperfusion, suggesting a mechanism for its cardioprotective effects.
Effect estimate: inhibited by 28%
p-value: p=< 0.05
AIMS: The possible contribution of the cardiac mitochondrial permeability transition pore (PTP) towards the cardioprotective effects of Na(+)-H(+) exchanger-1 (NHE-1) inhibition was studied in hearts subjected to ischaemia/reperfusion (IR). METHODS AND RESULTS: Langendorff-perfused rat hearts were subjected to 40 min of global ischaemia and 60 min of reperfusion in the presence or absence of the NHE-1 specific inhibitor AVE-4890 (AVE, 5 microM). Mitochondrial PTP opening was determined in the intact heart using 2-deoxy-(3)H-glucose entrapment and in isolated mitochondria by monitoring the decrease of the calcium-induced light scattering. Mitochondrial respiration was measured with a Clark-type oxygen electrode whereas release of apoptosis-inducing factor (AIF) and endonuclease G (EndoG) and levels of cleaved poly-(ADP-ribose) polymerase (PARP) were analysed by western blotting. IR induced mitochondrial PTP opening, which was inhibited by 28% (P < 0.05) with AVE treatment. Mitochondria isolated from AVE-treated hearts demonstrated significantly less calcium-induced swelling and higher substrate oxidation at complex I and II as well as cytochrome c oxidase and citrate synthase activity. AVE treatment also suppressed IR-induced release of AIF and EndoG from mitochondria, prevented the IR-induced rise in cleaved PARP levels, and was associated with significantly enhanced postischaemic recovery of left ventricular developed pressure and a significant decrease in lactate dehydrogenase release. AVE did not affect PTP opening directly in isolated mitochondria. CONCLUSION: The beneficial effect of NHE-1 inhibition in hearts subjected to IR is associated with attenuation of mitochondrial PTP opening and apoptosis and the resultant mitochondrial dysfunction. The effect of AVE on PTP opening most likely is indirect, as pore opening was not affected by direct administration of AVE to mitochondrial suspensions.
Javadov et al. (Tue,) conducted a other in Ischaemia/reperfusion. AVE-4890 (NHE-1 specific inhibitor) vs. Absence of AVE-4890 was evaluated on Mitochondrial PTP opening (inhibited by 28%, p=< 0.05). In isolated rat hearts subjected to ischaemia/reperfusion, NHE-1 inhibition with AVE-4890 reduced mitochondrial PTP opening by 28% (P < 0.05) and improved postischaemic recovery.