Dietary iron deficiency induces ventricular dilation, mitochondrial ultrastructural aberrations and cytochrome c release: involvement of nitric oxide synthase and protein tyrosine nitration

Abstract

Iron deficiency is associated with multiple health problems, including the cardiovascular system. However, the mechanism of action of iron-deficiency-induced cardiovascular damage is unclear. The aim of the present study was to examine the effect of dietary iron deficiency on cardiac ultrastructure, mitochondrial cytochrome c release, NOS (nitric oxide synthase) and several stress-related protein molecules, including protein nitrotyrosine, the p47phox subunit of NADPH oxidase, caveolin-1 and RhoA. Male weanling rats were fed with either control or iron-deficient diets for 12 weeks. Cardiac ultrastructure was examined by transmission electron microscopy. Western blot analysis was used to evaluate cytochrome c, endothelial and inducible NOS, NADPH oxidase, caveolin-1 and RhoA. Protein nitrotyrosine formation was measured by ELISA. Rats fed an iron-deficient diet exhibited increased heart weight and size compared with the control group. Heart width, length and ventricular free wall thickness were similar between the two groups. However, the left ventricular dimension and chamber volume were significantly enhanced in the iron-deficient group compared with controls. Ultrastructural examination revealed mitochondrial swelling and abnormal sarcomere structure in iron-deficient ventricular tissues. Cytochrome c release was significantly enhanced in iron-deficient rats. Protein expression of eNOS (endothelial NOS) and iNOS (inducible NOS), and protein nitrotyrosine formation were significantly elevated in cardiac tissue or mitochondrial extraction from the iron-deficient group. Significantly up-regulated NADPH oxidase, caveolin-1 and RhoA expression were also detected in ventricular tissue of the iron-deficient group. Taken together, these results suggest that dietary iron deficiency may have induced cardiac hypertrophy characterized by aberrant mitochondrial and irregular sarcomere organization, which was accompanied by increased reactive nitrogen species and RhoA expression.