[Mechanism of cardioprotection induced by noninvasive limb ischemic preconditioning]

To verify the inhibitory effect of mitochondrial calcium uniporter in remote preconditioning-induced cardioprotection.

By occlusion and reperfusion of left anterior descending artery, the rat hearts were subjected to 30 min regional ischemia and 120 min reperfusion in vivo. Thus the ischemic reperfusion model was established. The rats were randomly assigned to undergo one of the following maneuvers: (1) remote preconditioning; (2) ruthenium red (an inhibitor of mitochondrial calcium uniporter); (3) spermine or SB202190 (an opener of mitochondrial calcium uniporter). Remote preconditioning was elicited by three cycles of 5 min of right femoral artery occlusion interspersed with 5 min of reperfusion. The mean arterial blood pressure, heart rate and lactate dehydrogenase released in plasma were measured during reperfusion but the infarct size was measured after reperfusion.

In comparison with I/R group, remote preconditioning limited infarct size [(20.4 +/- 2.5)% vs (51.0 +/- 6.0)%] and lactate dehydrogenase release [(271 +/- 9) U/L vs (339 +/- 39)U/L] during reperfusion. On the contrary, spermine or SB202190 attenuated the reduction of infarct size and lactate dehydrogenase release induced by remote preconditioning. The group of spermine was [(40.8 +/- 9.2)% vs (20.4 +/- 2.5)%] and [(383 +/- 43) U/L vs (271 +/- 9) U/L] while the group of SB202190 was [(44.3 +/- 6.8)% vs (20.4 +/- 2.5)%] and [(356 +/- 26) U/L vs (271 +/- 9) U/L].

Inhibition of mitochondrial calcium uniporter opening is involved in the remote preconditioning-induced cardioprotection.