Capillary rarefaction occurs in many tissues in patients with essential hypertension and may contribute to an increased vascular resistance and impaired muscle metabolism. Rarefaction may be caused by a structural (anatomic) absence of capillaries, functional nonperfusion, or both. The aim of this study was to assess the extent of structural versus functional capillary rarefaction in the skin o...

Reversible perfusion defects on (99m)Tc-sestamibi imaging during hyperemia are thought to occur due to myocardial blood flow (MBF) "mismatch" between regions with and without stenosis. We have recently shown that myocardial blood volume (MBV) distal to a stenosis decreases during hyperemia, resulting in a reversible perfusion defect on myocardial contrast echocardiography (MCE). In this study, ...

Tumor hypoxia is a hallmark of malignant tumors, and is a major factor in the resistance to anti-cancer therapies, particularly radiotherapy. Indeed, tumor blood flow often fluctuates, and thus the oxygen supply is often reduced, thereby inducing tumor hypoxia. We decided to explore whether post-occlusive reactive hyperemia, a physiological reaction known to occur in normal tissues, could be ...

OBJECTIVES We investigated the value of reactive hyperemia peripheral arterial tonometry (RH-PAT) as a noninvasive tool to identify individuals with coronary microvascular endothelial dysfunction. BACKGROUND Coronary endothelial dysfunction, a systemic disorder, represents an early stage of atherosclerosis; RH-PAT is a technique to assess peripheral microvascular endothelial function. METHO...

This investigation tested the hypothesis that metabolic syndrome decreases the relative contribution of specific K(+) channels to coronary reactive hyperemia. Ca(2+)-activated (BK(Ca)), voltage-activated (K(V)), and ATP-dependent (K(ATP)) K(+) channels were investigated. Studies were conducted in anesthetized miniature Ossabaw swine fed a normal maintenance diet (11% kcal from fat) or an excess...

• Blood flow through skeletal muscle is augmented characteristically during and for some time after exercise.-' Information on the basic mechanism of this functional hyperemia is still far from complete. It has been suggested that vasomotor nerves or local chemical imbalances are concerned in the development and maintenance of vasodilatation. Similar uncertainty exists concerning the mechanism ...

Although skeletal muscle perfusion is fundamental to proper muscle function, in vivo measurements are typically limited to those of limb or arterial blood flow, rather than flow within the muscle bed itself. We present a noninvasive functional MRI (fMRI) technique for measuring perfusion-related signal intensity (SI) changes in human skeletal muscle during and after contractions and demonstrate...

The role of locally formed cyclo-oxygenase products (endoperoxide intermediates, prostaglandins, or prostacyclins) in resistance to blood flow was studied in the hindlimbs of anesthetized dogs during rest, during exercise, and following release of inflow occlusion. Meclofenamic acid, indomethacin, or sodium meclofenamate reduced mean resting blood flows of 86, 113, and 118 ml/min to 54, 82, and...

BACKGROUND During coronary stenosis, flow reserve in the adjacent nonstenotic bed decreases, but the microvascular mechanisms are unknown. Because myocardial contrast echocardiography (MCE) assesses microvascular physiology, we used it to relate flow reserve to intramyocardial blood volume in the adjacent bed. METHODS AND RESULTS A noncritical left anterior descending (LAD) stenosis was creat...

PURPOSE We tested the hypothesis that retinal blood flow has a postocclusive reactive hyperemia response modulated by occlusion duration and metabolic activity, and that choroidal blood flow does not. METHODS Anesthetized and paralyzed rats (n = 34) were studied. Retinal and choroidal blood flow was measured by laser speckle imaging and laser Doppler flowmetry, respectively. Blood oxygenation...