Silencing of the Na+/H+ exchanger 1(NHE-1) prevents cardiac structural and functional remodeling induced by angiotensin II

Chronic activation of the renin angiotensin system (RAS) favors several cardiac diseases, among which myocardial hypertrophy occupies an outstanding place. In this context, the hyperactivity of the cardiac Na+/H+ (NHE-1) exchanger plays a key role. The pathologic remodeling of the myocardium constitutes an independent risk factor for morbidity and mortality with continuously increasing healthcare cost. Therefore, the development of better therapeutic strategies emerges as highly mandatory. Our goal was to prevent angiotensin II (ANGII)-induced cardiac hypertrophy by NHE-1 gene silencing in Wistar rats. The intramyocardial injection of a lentivirus coding a specific small interference RNA (l-shNHE1) significantly reduced NHE-1 expression exclusively in the heart (similar to 50%) and prevented cardiac remodeling in rats exposed to chronic infusion of ANG II (heart weigh/tibia length: 24,03 +/- 0,7915 mg/mm vs 28,45 +/- 0,9779 mg/mm and collagen volume fraction 2526 +/- 0,5003 vs 5982 +/- 1043 in l-shNHE1 + ANGII and ANGII, respectively). Interestingly, this was accompanied by an improvement in cardiac function determined by echocardiography even though blood pressure remained elevated (Fractional shortening 0,5960 +/- 0,4228 vs -0,9567 +/- 0,06888 and blood pressure at the end of ANGII treatment 141,2 +/- 6117 mmHg vs 134,1 +/- 6723 mmHg; in l-shNHE1 + ANGII and ANGII, respectively). ANGII infusion increased myocardial NADPH oxidase activity but the l-shNHE1 injection prevented oxidative stress as revealed by the normalization of lipid peroxidation (T-BARS 12,40 +/- 2887.vs 23,05 +/- 1537 in l-shNHE1 + ANGII and ANGII, respectively). These results allow as to propose the partial silencing of the cardiac NHE-1 through lentiviral injection as a promising tool in the prevention of ANGII-induced cardiac hypertrophy.