Participation of L-lactate in the cardioprotective effect of remote ischemic postconditioning in young and old rats

Abstract

Background. The development of new effective methods for preventing or mitigating ischemic and reperfusion injury to the myocardium and elucidating their mechanisms is an urgent task of modern experimental and clinical medicine. Remote ischemic postconditioning (RIPost) is a promising non-invasive method that can effectively and safely reduce the size of myocardial infarction. The aim of the study was to elucidate the involvement of L-lactate in the infarct-limiting effect of RIPost in young and old rats. Methods. The study of the participation of L-lactate in the realization of the cardioprotective effect of RIPost in ischemia-reperfusion (I/R) of the myocardium was performed on 120 mongrel white male rats (60 young rats weighing 200-240 g and aged 4±1 months and 60 old rats weighing 400-450 g and aged 24±1 months). Coronary occlusion (30 min) and reperfusion (2 h) were performed to model myocardial infarction. The necrotic zone area and area at risk were measured. RIPost was modeled by clamping the hind limbs for 15 minutes 10 minutes after the start of reperfusion. The concentration of L-lactate in blood plasma was measured in the RIPost model (by 15-minute ischemia of both femoral arteries 10 min after 30-minute acute coronary occlusion). Postconditioning with L-lactate (PostL) was produced by injecting L-lactate 10 mg/kg into the left common jugular vein 25 minutes after the start of reperfusion. Results. In young and old rats, after the 15-minute clamping of both femoral arteries during RIPost, blood plasma concentrations of L-lactate increased 2.28 and 2.34 times, respectively. The sizes of the necrotic zone in the studied groups were as follows: I/R_young was 45±4, I/R_old, 47±5, RIPost_young, 25±3 (p<0,001), RIPost_old, 28±3 (p<0,001), I/R+Saline_young – 45±6, I/R+Saline_old – 48±6, PostL_young, 33±3 (p<0,01), and PostL_old, 35±4% (p<0,01). Conclusions. RIPost has an infarction-limiting effect and is accompanied by an increase in the blood plasma concentration of L-lactate. It was found that PostL leads to a decrease in the size of the necrosis zone in the myocardium of the left ventricle in young and old rats by 26.7 and 25.5%, respectively.