Učinak aerobnog intervalnog treninga na patološko remodeliranje i mitohondrijsku disfunkciju u štakora s poslijeinfarktnim zatajenjem srca

Aims: Following a large myocardial infarction (MI), remaining viable muscle often undergoes pathological remodelling and progresses towards chronic heart failure (CHF). Mitochondria may also be affected by this process and, due to their functional importance, likely contribute to the progression of the disease. Aerobic interval training (AIT) has been shown effective in diminishing pathological myocardial transformation, but the effects of AIT on mitochondrial function in hearts undergoing remodelling are not known. Methods and Results: Adult female Sprague-Dawley rats were randomized to either 8 weeks of aerobic interval treadmill running (5 days/week), which started 4 weeks after left coronary artery ligation (MI-Trained), or a sedentary group (MI-Sedentary). Echocardiography was performed before and after the 8-week period, at which point the left ventricles (LV) were also harvested. Twelve weeks after surgery, MI-Sedentary rats had significantly lower LV fractional shortening compared to MI-Trained. Complex I – dependent respiration assessed in isolated LV mitochondria was decreased by ~37% in MI-Sedentary and 17% in MI-Trained (group differences p<0.05), compared to sham-operated animals. This was paralleled with diminished ATP-production and increased degree of protein oxidation in MI-Sedentary rats. The enzymatic activity of complex I was also decreased to the greater extent in MI-Sedentary than in MI-Trained animals, with no evidence of its reduced expression. When complex II substrate was used, no differences among the three groups were observed. Conclusions: Exercise reduces the left ventricle contractile deterioration in post-infarction heart failure and alleviates the extent of mitochondrial dysfunction, which is paralleled with preserved complex I activity.Uvod: Nakon opsežnog infarkta miokarda (IM) u dijelu srčanog mišića izvan zahvaćenog područja dolazi do patološkog remodeliranja koje ako napreduje dovodi do razvoja kroničnog srčanog zatajenja. Patološko remodeliranje obuhvaća makroskopske i mikroskopske promjene na razini srčanog mišića. Remodeliranje na razini mitohondrija vjerojatno je važni čimbenik napredovanja bolesti zbog njihove ključne uloge u energijskom metabolizmu stanice. Aerobna intervalna tjelovježba učinkovito ublažava patološku transformaciju miokarda iako još uvijek nisu dovoljno istraženi mehanizmi preko kojih se to događa. Materijali i metode: Ženke štakora Sprague-Dawley randomizirane su u dvije skupine: jedna je skupina 4 tjedna nakon podvezivanja lijeve koronarne arterije bila podvrgnuta aerobnoj intervalnoj tjelovježbi koja se sastojala od trčanja na pokretnoj traci (5 dana/tjedan) dok je druga tijekom istog razdoblja živjela sedentarnim životom. Prije i poslije perioda tjelovježbe od 8 tjedana učinjeno je ehokardiografsko testiranje. Nakon provedenih ispitivanja životinje su bile žrtvovane, a iz srca izolirani dijelovi lijevog ventrikula izvan područja zahvaćenog infarktom. Rezultati: 12 tjedana nakon kirurškog zahvata sedentarne su životinje imale značajno nižu frakciju skraćenja lijevog ventrikula u usporedbi s treniranim životinjama. U mitohondrijima izoliranim iz lijevog ventrikula respiracija preko kompleksa I bila je 37% manja u sedentarnih i 17% manja u treniranih životinja (statistička razlika p