INHIBITION OF RAS COMPONENTS ATTENUATES PROGRESSION OF MYOCARDIAL REMODELING IN BOTH NORMOTENSIVE AND HYPERTENSIVE RATS IN EXPERIMENTAL HEART FAILURE

Abstract

Objective: New findings in the pathogenesis of heart failure (HF) with a focus on extracellular matrix (ECM) and communication in the heart are still relevant for more effective treatment. We focused on signaling pathways involved in cardiac structural remodeling in HF due to pressure and volume overload, as well as on investigating the efficacy of substances with possible antifibrotic potential. Design and method: We used as experimental model 28-week-old hypertensive (TGR) and normotensive (HSD) rats with created aortocaval fistula (ACF), supplemented with ACE inhibitor (ACEi) (Trandolapril, 15 weeks, 6 mg/L) and AT1 receptor blocker (ARB) (Losartan, 15 weeks, 200 mg/L). Results: Echocardiography confirmed an increase in cardiac output and a decrease in ejection fraction in both strains of rats. BW was higher in TGR vs HSD and it was not affected by VO. ACF-induced cardiac volume overload, elevated markers of heart failure and oxidative damage, ANP, BNP-45, and TBARS, were elevated in the blood serum of both strains. ACF induced profibrotic signaling by increasing TGF-, and mRNA collagen I, and collagen I protein expression in the left and right ventricles of HSD rats. In TGR rats ACF decreased TGF- and SMAD2 protein expression in the right ventricle similar to HSD rats, in which ACF also suppressed MMP-2 protein expression. Heart failure affected protein kinase signaling by reducing the protein expression of PKC, PKG, and in part, PKC in both chambers of the heart of both strains. ACF decreased the protein expression of Cx43 and its phosphorylated form, which is significantly proarrhythmic. Hypertension in TGR rats increased mRNA TGF- expression and collagen I, but decreased PKC and PKC protein expression and increased PKC. Conclusions: A notable finding was that the signaling pathways involved in cardiac remodeling were more normalized by the ARB, while proteins involved in intercellular communication, ACEi. The results of analyzes of both experiments indicate attenuated responses of the signaling pathways monitored by us in the heart of hypertensive strains reflecting adaptation to primarily induced pathophysiology. Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic VEGA 2/0158/19, 2/0002/20