CARDIOPROTECTIVE EFFICIENCY OF POSTCONDITIONING WITH L-LACTATE IN MYOCARDIAL ISCHEMIA-REPERFUSION IN YOUNG AND OLD RATS AND THE IMPORTANCE OF NO-SYNTHASE AND M-CHOLINERGIC SYSTEMS ACTIVITY IN ITS IMPLEMENTATION

Purpose – to study the cardioprotective efficacy of postconditioning with L-lactate (PostL) during myocardial ischemia-reperfusion in young and old rats and to elucidate the role of NOsynthase (NOS) and M-cholinergic reactive system (M-CRS) activity in its implementation.

Methods. The study was conducted on young and old anesthetized nonlinear white male rats. The animals were ventilated with room air via a tracheostomy. The right carotid artery and left internal jugular vein were cannulated to measure blood pressure and administer drugs. An electrocardiogram (ECG) was continuously recorded in lead II throughout the experiment. The animals underwent coronary occlusion (30 min) and reperfusion (2 h). The size of the necrotic zone and the risk zone were assessed using computerized planimetry. PostL was modeled 25 min after the start of reperfusion by administering a solution of L-lactate neutralized with NaOH at a dose of 10 mg/kg. The NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) was administered to rats at a dose of 25 mg/kg immediately after coronary occlusion, and the 0.2 % M-CRS blocker atropine at a dose of 2 mg/kg was administered 10 min before PostL.

Results. PostL exerts a cardioprotective effect and leads to a decrease in the size of the necrotic zone in the left ventricular myocardium in young and old animals by 26.7 and 25.5 % (p < 0.01), respectively. Pretreatment with both the NOS inhibitor L-NAME and the M-CRS blocker atropine abolished the cardioprotective effect of PostL in young but not old rats, indicating the importance of NOS and L-NAME in mediating the cardioprotective effect of PostL in young but not old rats.

Conclusion. The activity of M-СRC, like NOS, is important in the implementation of the cardioprotective effect of PostL during myocardial ischemia-reperfusion in rats, depending on their age.

Following systemic administration of both the NOS inhibitor L-NAME and the M-CRS blocker atropine, the cardioprotective effect of PostL is maintained in old but not young rats.

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