Normalization of the calcineurin pathway underlies the regression of hypertensive hypertrophy induced by Na+/H+ exchanger-1 (NHE-1) inhibitionThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute

• Published in: Canadian journal of physiology and pharmacology 2007-03, Vol.85 (3-4), p.301-310
• Main Authors: Ennis, Irene L, Garciarena, Carolina D, Escudero, Eduardo M, Pérez, Néstor G, Dulce, Raúl A, Camilión de Hurtado, María C, Cingolani, Horacio E
• Format: Article
• Language: English
• Subjects: calcineurin; calcineurine; cardiac hypertrophy; hypertrophie cardiaque; NHE-1
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/y06-072

Na + /H + exchanger-1 (NHE-1) inhibition induces cardiac hypertrophy regression and (or) prevention in several experimental models, although the intracellular events involved remain unclarified. We aimed to determine whether the calcineurin/NFAT pathway mediates this effect of NHE-1 inhibitors. Spontaneously hypertensive rats (SHR) with cardiac hypertrophy were treated with the NHE-1 inhibitors cariporide and BIIB723 for 30 days. Wistar rats served as normotensive controls. Their hearts were studied by echocardiography, immunoblotting, and real-time RT-PCR. Cytoplasmic Ca 2+ and calcineurin A β expression were measured in cultured neonatal rat ventricular myocytes (NRVM) stimulated with endothelin-1 for 24 h. NHE-1 blockade induced cardiac hypertrophy regression (heart mass/body mass = 3.63 ± 0.07 vs. 3.06 ± 0.05 and 3.02 ± 0.13 for untreated vs. cariporide- and BIIB723-treated SHR, respectively;; p < 0.05) and decreased myocardial brain natriuretic peptide, calcineurin A β, and nuclear NFAT expressions. Echocardiographic evaluation demonstrated a reduction in left ventricular wall thickness without changes in cavity dimensions or a significant decrease in blood pressure. NHE-1-inhibitor treatment did not affect myocardial stiffness or endocardial shortening, but increased mid-wall shortening, suggesting that a positive inotropic effect develops after hypertrophy regression. Cariporide normalized the increased diastolic Ca 2+ and calcineurin A β expression observed in ET-1-stimulated NRVM. In conclusion, our data suggest that inactivation of calcineurin/NFAT pathway may underlie the regression of cardiac hyper-trophy induced by NHE-1 inhibition.