Hypertension-induced cardiac hypertrophy alters the amplitude and time course of the systolic Ca2+ transient of subepicardial and subendocardial ventricular myocytes. The present study was designed to elucidate the mechanisms underlying these changes. Myocytes were isolated from the left ventricular subepicardium and subendocardium of 20-wk-old spontaneously hypertensive rats (SHR) and age-matc...

The left ventricular (LV) coronary-perfused canine wedge preparation is a model commonly used for studying cardiac repolarization. In wedge studies, transmembrane potentials typically are recorded; whereas, extracellular electrical recordings are commonly used in intact hearts. We compared electrically measured activation recovery interval (ARI) patterns in the intact heart with those recorded ...

The concentration of radioiodinated (Fab')2 fragments of cardiac specific antimyosin antibody in myocardial infarcts has been shown previously to be inversely proportional to regional myocardial blood flow. The myocardial localization of antibody fragments has also been visualized by gamma camera scintigraphy. We now correlate the site of 121I-antimyosin (Fab')2 uptake with histochemical and hi...

The diagnostic approach of patients with coronary artery disease normally relies on the assessment of global and regional perfusion and contraction in the normal and pathological areas of the myocardium. However, experimental pathophysiological studies have clearly shown that microvascular flow, metabolic consumption and the strength of contraction do not behave homogeneously in the different t...

The presence of a coronary stenosis results primarily in subendocardial ischemia. Apart from the decrease in coronary perfusion pressure, a stenosis also decreases coronary flow pulsations. Applying a coronary perfusion system, we compared the autoregulatory response of subendocardial (n = 10) and subepicardial (n = 12) arterioles (<120 microm) after stepwise decreases in coronary arterial pres...

The concentration of radioiodinated (Fab')2 fragments of cardiac specific antimyosin antibody in myocardial infarcts has been shown previously to be inversely proportional to regional myocardial blood flow. The myocardial localization of antibody fragments has also been visualized by gamma camera scintigraphy. We now correlate the site of 121I-antimyosin (Fab')2 uptake with histochemical and hi...

Acute left circumflex coronary artery (LC) occlusion in conscious dogs caused marked ischemia in the myocardium supplied by the occluded artery, as judged by the radioactive microsphere technique for determining blood flow distribution. With the chest open, LC pressure distal to the occlusion fell to 21 ± 1.9% of aortic pressure. By 8 weeks after gradual LC occlusion with an ameroid constrictor...

BACKGROUND Certain alterations by mutations or drugs of the potassium currents I(Ks) and I(Kr) and the sodium current I(Na) give rise to several types of the long-QT syndrome. I(Ks) is heterogeneously distributed across the ventricular wall. METHODS AND RESULTS We investigated the effects of reducing I(Ks) or I(Kr) or enhancing late I(Na) (to simulate the 3 forms of long-QT syndrome) on actio...

With aging, structural and functional changes occur in the myocardium without obvious impairment of systolic left ventricular (LV) function. Transmural differences in myocardial vulnerability for these changes may result in increase of transmural inhomogeneity in contractile myofiber function. Subendocardial fibrosis and impairment of subendocardial perfusion due to hypertension might change th...

Computations of compliance of the left ventricle (LV) during diastole assume passive tissue characteristics. To evaluate this assumption, we measured diastolic LV intramyocardial pressure simultaneously in the subepicardium and subendocardium in 18 open-chest dogs, using 1-mm in diameter micromanometers. Subepicardial pressure, 26 +/- 1 mm Hg (mean +/- SEM) exceeded subendocardial pressure, 14 ...