Genetic iNOS deficiency or selective iNOS inhibition with 1400W significantly attenuated transverse aortic constriction-induced myocardial hypertrophy, dilation, fibrosis, and dysfunction in mice.
Does iNOS deficiency or pharmacological inhibition prevent systolic overload-induced ventricular hypertrophy and heart failure in a mouse model?
Genetic deficiency or pharmacological inhibition of iNOS protects against pressure overload-induced cardiac hypertrophy and dysfunction in mice, highlighting iNOS as a potential therapeutic target for heart failure.
Inducible nitric oxide synthase (iNOS) protein is expressed in cardiac myocytes of patients and experimental animals with congestive heart failure (CHF). Here we show that iNOS expression plays a role in pressure overload-induced myocardial chamber dilation and hypertrophy. In wild-type mice, chronic transverse aortic constriction (TAC) resulted in myocardial iNOS expression, cardiac hypertrophy, ventricular dilation and dysfunction, and fibrosis, whereas iNOS-deficient mice displayed much less hypertrophy, dilation, fibrosis, and dysfunction. Consistent with these findings, TAC resulted in marked increases of myocardial atrial natriuretic peptide 4-hydroxy-2-nonenal (a marker of lipid peroxidation) and nitrotyrosine (a marker for peroxynitrite) in wild-type mice but not in iNOS-deficient mice. In response to TAC, myocardial endothelial NO synthase and iNOS was expressed as both monomer and dimer in wild-type mice, and this was associated with increased reactive oxygen species production, suggesting that iNOS monomer was a source for the increased oxidative stress. Moreover, systolic overload-induced Akt, mammalian target of rapamycin, and ribosomal protein S6 activation was significantly attenuated in iNOS-deficient mice. Furthermore, selective iNOS inhibition with 1400W (6 mg/kg per hour) significantly attenuated TAC induced myocardial hypertrophy and pulmonary congestion. These data implicate iNOS in the maladaptative response to systolic overload and suggest that selective iNOS inhibition or attenuation of iNOS monomer content might be effective for treatment of systolic overload-induced cardiac dysfunction.
Zhang et al. (2007) studied Systolic overload-induced ventricular hypertrophy and congestive heart failure. iNOS deficiency and selective iNOS inhibition (1400W) vs. Wild-type mice was evaluated on Myocardial chamber dilation, hypertrophy, fibrosis, and dysfunction. Genetic iNOS deficiency or selective iNOS inhibition with 1400W significantly attenuated transverse aortic constriction-induced myocardial hypertrophy, dilation, fibrosis, and dysfunction in mice.