Hiroyuki Tsutsui

Oxidative stress, defined as an excess production of reactive oxygen species (ROS) relative to antioxidant defense, has been shown to play an important role in the pathophysiology of cardiac remodeling and heart failure (HF). It induces subtle changes in intracellular pathways, redox signaling, at lower levels, but causes cellular dysfunction and damage at higher levels. ROS are derived from several intracellular sources, including mitochondria, NAD(P)H oxidase, xanthine oxidase, and uncoupled n

Recent experimental and clinical studies have suggested that oxidative stress is enhanced in myocardial remodelling and failure. The production of oxygen radicals is increased in the failing heart, whereas normal antioxidant enzyme activities are preserved. Mitochondrial electron transport is an enzymatic source of oxygen radical generation and can be a therapeutic target against oxidant-induced damage in the failing myocardium. Chronic increases in oxygen radical production in the mitochondria

Cardiac hypertrophy in response to systolic pressure loading frequently results in contractile dysfunction of unknown cause. In the present study, pressure loading increased the microtubule component of the cardiac muscle cell cytoskeleton, which was responsible for the cellular contractile dysfunction observed. The linked microtubule and contractile abnormalities were persistent and thus may have significance for the deterioration of initially compensatory cardiac hypertrophy into congestive he

The mechanism by which beta blockade improves left ventricular dysfunction in various cardiomyopathies has been ascribed to improved contractile function of the myocardium or to improved beta-adrenergic responsiveness. In this study we tested two hypotheses: (a) that chronic beta blockade would improve the left ventricular dysfunction which develops in mitral regurgitation, and (b) that an important mechanism of this effect would be improved innate contractile function of the myocardium. Two gro