The effects of /3-adrenergic blockade on cardiac transcapillary exchange were examined at rest and during sympathetic stimulation. Multiple indicator dilution experiments were carried out in closed-chest anesthetized dogs at rest and during carotid occlusion, either under basal conditions or after fJ-adrenergic blockade with alprenolol. jB-Adrenergic blockade at rest had no effect on coronary f...

The heart muscle is nourished by a complex system of blood vessels that make up the coronary circulation. Here we show that the design of the coronary circulation has a functional hierarchy. A full anatomic model of the coronary arterial tree, containing millions of blood vessels down to the capillary vessels, was simulated based on previously measured porcine morphometric data. A network analy...

P ulmonary arteriovenous malformations (PAVMs) carry significant risks [1, 2]. Pulmonary arterial blood passing through these right-to-left shunts cannot be oxygenated, leading to hypoxaemia, with arterial oxygen tension and arterial oxygen saturation (Sa,O2) inversely related to the size of the shunt fraction. The fragile wall of the PAVM sac may rupture, leading to haemoptysis or haemothorax ...

PURPOSE Our objective was to demonstrate sonographically the flow distribution in the circulation of human placentae as well as the sensitivity of the human fetal capillary bed to vasoconstriction and dilatation. METHODS Five human full-term placental lobules were maintained in vitro with fetal and maternal flow. Commercial ultrasound scanners were used for imaging. Albunex (1 ml bolus) was a...

I.V. fluid therapy does not result in the extracellular volume distribution expected from Starling's original model of semi-permeable capillaries subject to hydrostatic and oncotic pressure gradients within the extracellular fluid. Fluid therapy to support the circulation relies on applying a physiological paradigm that better explains clinical and research observations. The revised Starling eq...

Herein we describe a simple platform for rapid DNA amplification using convection. Capillary convective PCR (CCPCR) heats the bottom of a capillary tube using a dry bath maintained at a fixed temperature of 95°C. The tube is then cooled by the surrounding air, creating a temperature gradient in which a sample can undergo PCR amplification by natural convection through reagent circulation. We de...

To investigate the relationships between local platelet activation in pulmonary vessels and pulmonary artery pressure circulating platelet aggregates and plasma beta-thromboglobulin (beta-TG) levels were evaluated in peripheral venous blood and blood from different sites of pulmonary circulation (right ventricle, pulmonary artery and arteriolo-capillary bed) in 29 patients with COPD. Fifteen ha...

The postarteriolar response of capillary transport and microvascular flow distribution to muscle contraction and to adenosine was measured by the indicator dilution technique in isolated dog gracilis muscles perfused with blood at controlled flows. A model of dual circulation was used to analyze the partition of microvascular flow. The extraction (E) of 125I-iodoantipyrine (IAp) served as an in...

The retinal circulation in the cat teas studied by intravital microscopy, and experiments confirmed that the passage of red cells in the capillaries is intermittent, although plasma may be circulating continuously. Preferential pathways, in which blood fiows almost continuously, have been found in the superficial capillary network, forming a direct communication betioeen arterioles and venules....

The small molecular weight peptide, atrial natriuretic peptide (ANP), produces marked sodium and water excretion. The peptide, extracted from several species of vertebrate heart, also has been shown to increase glomerular filtration and reduce plasma volume. Several mechanisms have been proposed to account for the action of the peptide but remain undefined. In the present report, the ANP-induce...