Isolation, long-term culture, and ultrastructural characterization of adult cardiomyopathic cardiac muscle cells

NOX5 expression is increased in intramyocardial blood vessels and cardiomyocytes after acute myocardial infarction in humans

Reactive oxygen species producing NADPH oxidases play important roles under different (patho)physiological conditions. NOX1, NOX2, and NOX4 are important sources of reactive oxygen species in the heart, but knowledge of the calcium-dependent NOX5 in the heart is lacking. The presence of NOX5 was studied via RT-PCR in heart tissue from patients with end-stage heart failure; the tissue was obtained during cardiac transplantation surgery. NOX5 positivity and cellular localization were studied via IHC and digital-imaging microscopy in heart tissues of patients who did not have heart disease and in infarction areas of patients who died of myocardial infarctions of different durations. Furthermore, NOX5 expression was analyzed in vitro by using Western blot analysis. NOX5 RNA was found in the hearts of controls and patients with ischemic cardiomyopathy. In controls, NOX5 localized to the endothelium of a limited number of intramyocardial blood vessels and to a limited number of scattered cardiomyocytes. In infarcted hearts, NOX5 expression increased, especially in infarctions >12 hours, which manifested as an increase in NOX5-positive intramyocardial blood vessels, as well as in endothelium, smooth muscle, and cardiomyocytes. NOX5 was found in cardiomyocyte cytoplasm, plasma membrane, intercalated disks, and cross striations. Western blot analysis confirmed NOX5 expression in isolated human cardiomyocytes. For the first time to our knowledge, we demonstrate NOX5 expression in human intramyocardial blood vessels and cardiomyocytes, with significant increases in the affected myocardium after acute myocardial infarction.

Cardiac ultrastructural abnormalities in Syrian hamsters with spontaneous cardiomyopathy or subjected to cardiac overloads

Ultrastructural and morphometric abnormalities of Syrian hamster cardiomyopathy were compared to those observed in two different models of cardiac hypertrophy produced by mechanical overload (abdominal aortic stenosis, 60-day duration) or by isoproterenol injection during 15 days in normal Syrian hamsters of the same strain. Aspects of increased protein synthesis were observed in all three groups of animals. This was the only abnormality observed in the aortic stenosis group. Cardiomyopathy was different from the two other types of overload by the existence of large calcium deposits inside of the myocytes, by the presence of thin filaments and amorphous material accumulation suggesting abnormal synthesis and by a significant reduction of myofibrils at the heart-failure phase. Nuclear abnormalities with nuclear constrictions suggesting a division process and an increased number of myocytes with two nuclei were present in both spontaneous cardiomyopathy and isoproterenol-induced cardiopathy. Therefore, Syrian hamster cardiomyopathy appears to be different from cardiopathy induced by hemodynamic overload but, in spite of specific aspects, resembles that induced by isoproterenol injections, strengthening the hypothesis of a pathogenic role of catecholamines in the Syrian hamster cardiomyopathy.