Resumo

D'ANNUNZIO, Verónica et al. Ischemic Postconditioning Reduces Infarct by Activating Adenosine Receptors in Animals with Normal and High Cholesterol Levels. Rev. argent. cardiol. [online]. 2006, vol.74, n.4, pp.224-228. ISSN 1850-3748.

Ischemic postconditioning (Postcon) reduces infarct size in normal animals. However, since the effect of Postcon in hypercholesterolemic animals is unknown, our objective was to determine whether Postcon reduces infarct size in hypercholesterolemic animals. The second objective was to assess if A₁ receptors are involved in protective Postcon mechanisms. Isolated isovolumic hearts of normal and hypercholesterolemic rabbits were perfused according to Langendorff's technique and subjected to 30 minutes of global ischemia and 30 min of reperfusion (G1). During G2, Postcon was elicited (two 30 second-cycles of reperfusion/ ischemia) after 30 min of ischemia. During G3, we repeated G2, but an A₁ receptor blocker (DPCPX, 200 nM) was administered. During G4, G5 and G6, all these experimental protocols were repeated in animals fed with a cholesterolrich diet (1%) for 4 weeks. The following parameters were measured: pressure developed in the left ventricle (LVP), end-diastolic LV pressure (LVEDP), and infarct size assessed by triphenyl tetrazolium (TTC). The infarct size was 15.7±1.5% in G1 and 24.4±3.1% in G4. Postcon reduced the infarct area to 5.5±0.9% in normal animals and to 5.6±1.6% in hypercholesterolemic animals (p<0.05 vs. G1 and G4). When DPCPX was administered, the protective effect of Postcon was abolished in both groups of animals (G3, 15.1±1.7 and G6, 21.2±1.9). Hence, Postcon reduces infarct size in normal and hypercholesterolemic animals, through the activation of A₁ receptors.

Palavras-chave : Myocardial infarction; Ischemic postconditioning; Hypercholesterolemia.