We sought to ascertain the rates and mechanisms of uptake of markers for regional myocardial blood flows. The rates of exchange of potassium and thallium across capillary walls and cell membranes in isolated blood-perfused dog hearts were estimated from multiple indicator dilution curves recorded for 131I-albumin, 42K and 201Tl from ...

We previously found that local O2 extraction efficacy in isolated pump-perfused intestine was enhanced when systemic reflex vasoconstriction was stimulated by hypovolemia (Samsel, R.W., and P.T. Schumacker. 1994. J. Appl. Physiol. 77: 2291-2298). The microvascular mechanism underlying this beneficial effect could involve a redistribution of flow between mucosa and serosa, ...

Although the capillary wall represents an active interface between blood and tissue, the potential role of the capillary in blood flow control has not been determined. The goals were (i) to establish the presence of the capillary sensing and communication phenomenon (Dietrich and Tyml, Microvasc. Res. 43, 87-99, 1992) in ...

The dynamics and regulation of red blood cell flow in the cerebral microcirculation was studied by intravital fluorescence video-microscopy in a closed cranial window preparation in the rat. The studies revealed that capillary perfusion in the brain is essentially continuous but a stationary difference from capillary to capillary within the ...

The nutritional blood vessel system in the anagen (growing) vibrissal follicle consists of a rete capillare papillae pili, rete capillare bulbi pili, rete capillare folliculi pili, and rete capillare canalis pili. Due to degeneration of papilla and bulb during the sinus hair cycle, the basal capillary networks are absent in ...

A modern understanding of oedema formation traditionally begins with Starling's description in 1898 of hydrostatic and oncotic forces acting on the capillary membrane. Clearly, hypotheses of oedema formation predating the knowledge of the existence of capillaries must have been incomplete. Marcello Malpighi first described capillaries in 1661, but although he ...

Rapid ascent to altitude risks the development of acute mountain sickness. This study demonstrates changes in peripheral capillary filtration coefficient and renal protein loss in subjects suffering from various degrees of mountain sickness after passive ascent to 4559 m. Capillary filtration coefficient of the calf capillary bed, measured by computer-based ...

By using nailfold videomicroscopy in conjunction with local cold exposure, the haemodynamic responses in capillary blood cell velocity were evaluated in 12 patients with vasospastic disease after receiving L-carnitine 3 g per day orally for 20 days. The results obtained showed that the cold-induced blood flow stop duration was significantly ...

The present study was undertaken to explore the cause of postischaemic hypoperfusion through morphological observations of the microstructure of brain cortex capillaries in rats with postischaemic hypoperfusion. Sixteen rats were used. The left middle cerebral artery of each animal was occluded for one hour (n = 8) or 2 hours ...

The blood vessels of the medulla oblongata and pons are arranged into anterior (medial), lateral, and posterior groups. Particular part of the brain receive also blood from several sides (medial, lateral, posterior) what secures rich capillary net and vascular loops. Venous blood is drained by veins running in the same ...

In an overview the microvascular involvement in chronic venous insufficiency (CVI) is described. Microangiopathy in the lower leg areas is characterized by the presence of typical enlarged and ramified blood capillaries, reduced capillary number, microvascular thrombosis and obliterations, and/or increased permeability of microlymphatics. Transcutaneous oxygen tension (tcPO2) is decreased and ...

In psoriatic lesions, capillaries in the papillary bodies seem elongated and increased in number. Most researchers postulate that there is angiogenesis of intrapapillary capillaries in psoriatic plaques. In this study we will show, by means of computer-aided three-dimensional reconstructions in four patients suffering from chronic plaque-type psoriasis, and in a ...

INTRODUCTION: The present study compared blood lactate and glucose values obtained from capillary and venous samples, and examined the utility of a modified capillary tube (55 mm in length) for a YSI 2300 Stat analyzer. METHODS: Sixteen subjects (17-26 yrs) completed a graded exercise test using a cycle ergometer. Blood ...

Previous analyses of developmentally programmed capillary regression suggested two distinct causes of vascular endothelial cell (VEC) death. The first appeared to be macrophage-dependent (Lang, R. A. and Bishop, M. J. (1993) Cell 74, 453-462) while the second was proposed to result from cessation of blood flow (Lang, R. A., Lustig, ...

The contribution of preglomerular resistance changes to the tubuloglomerular feedback (TGF) effector response was evaluated by micropuncture in hydropenic rats. Studies were performed in free-flowing nephrons to compare the fractional compensation (C) for perturbations in late proximal flow (VLP) with associated changes in glomerular capillary hydrostatic pressure (PGC). VLP was ...

PURPOSE: To study macular capillary blood flow velocity during pregnancy and postpartum in diabetic women with minimal diabetic retinopathy. METHODS: Macular capillary blood velocity was measured using the blue-field entoptic simulation technique in 17 type I diabetic pregnant women with minimal background retinopathy and 10 healthy pregnant women at the ...

The aim of this study was to confirm that microvascular perfusion was abnormal during the early phases of normotensive sepsis and to determine whether these changes were due to the development of tissue edema. Skeletal muscle red blood cell (RBC) flow was studied in rats made septic by cecal ligation ...

Postnatal development of the blood vasculature in the rat adrenal gland was examined with scanning electron microscopy (SEM), using a microcorrosion casting method. The cortical vascular bed on postnatal day 1 (P1) was incipient, consisting of an outer capillary layer and an inner sinusoidal vascular layer of the juxtamedullary zone. ...

OBJECTIVE: As a first step in modeling microvascular exchange in the renal medulla, we developed mathematical models to explore the effects of blood flow, permeability, and anatomical arrangement of microvessels on the steady-state distribution of solute in the blood and the interstitial fluid (ISF). METHODS: Single capillaries and countercurrent capillary ...

A thick endothelial surface coat consisting of the glycocalyx and associated plasma proteins has been hypothesized to reduce functional capillary volume available for flowing plasma macromolecules and blood cells. The purpose of this study was to compare anatomic and functional capillary diameters available for macromolecules, RBCs, and WBCs in hamster ...

We tested the hypothesis that endotoxin increases the heterogeneity of gut capillary transit times and impairs oxygen extraction. The gut critical oxygen extraction ratio was determined by measuring multiple oxygen delivery-consumption points during progressive phlebotomy in eight control and eight endotoxin-infused anesthetized pigs. In multiple 1- to 2-g samples of ...

PURPOSE: To study the flow velocity of erythrocytes and leukocytes in the same retinal capillaries in cat eyes. METHODS: Blood cells from cats were stained with fluorescent label and reinjected into the animals. An electro-optical device combined with a highly sensitive CCD camera detected the fluorescent signal from the labeled ...

Although milk yield of cows and goats is known to be closely related to the total flow of blood through the udder, a number of studies suggest that milk yield can vary independently. No studies have attempted to measure the proportion of total flow that is nutritive. Within the mammary ...

We have applied the phosphorescence lifetime technique (Vanderkooi, J. M., G. Maniara, T. J. Green, and D. F. Wilson. J. Biol. Chem. 262: 5476-5482, 1987) to determine oxygen tension in single capillaries of the hamster retractor muscle. Palladium meso-tetra(4-carboxyphenyl)porphine (10 mg/ml, pH 7.40, bound to bovine serum albumin) was used ...

The microvasculature of the rat retina was studied in male Wistar rats in order to examine the features of the precapillary vascular pattern and structure that could affect blood flow regulation. Vascular corrosion casts and partially digested tissue specimens were observed by scanning electron microscopy. Side branching rather than bifurcation ...

Nitric oxide (NO) has been shown to be a potent vasodilator released from endothelial cells (EC) in large blood vessels, but NO release has not been examined in the capillary bed. Because the capillary bed represents the largest source of EC, it may be the largest source of vascular NO. ...

We describe the use of gelatinase standards from human capillary whole blood for calibrating gelatin zymograms. Capillary blood was obtained by fingerstick puncture and prepared in nonreducing Laemmli SDS-PAGE sample buffer without heating. Gelatin zymography revealed that whole blood (0.25- 1 microliter) contained substantial fibroblast-derived (72-kDa) and neutrophil-derived (92-, 130-, ...

We measured the venous concentration versus time curves of 14C-urea and 14C-primidone after rapid bolus injections of a vascular reference indicator, fluorescein isothiocyanate dextran, and one of the two 14C-labeled indicators in isolated rabbit lungs perfused with Krebs-Ringer bicarbonate solution containing 4.5% bovine serum albumin at flow rates (F) of ...

The etiology of noise-induced hearing loss is poorly understood despite years of clinical experience and experimental investigations. One potential mechanism which may contribute to noise-induced temporary threshold shifts (TTS) are vascular pathologies in the microcirculation of the cochlea. Several studies have demonstrated histologic evidence of reduced cochlear blood flow following ...

Perilymph is separated from blood by a barrier called the blood-labyrinth or blood-perilymph barrier in analogy to the blood-brain or blood-cerebrospinal fluid barrier. These barriers consist mainly of vascular endothelial cells. To characterize the blood-labyrinth barrier we developed in vitro techniques for the quantitative determination of the osmotic water permeability ...

Plasma perfusion patterns were investigated in brain capillaries during decreased cerebral blood flow induced by hyperventilation. Anesthetized rats were decapitated 3-4 s after being given an intravenous bolus injection of Evans blue dye. the measured steep increase of the arterial dye concentration at this moment ensures that different capillary plasma ...

We examined the periodicity and intravascular distribution of Wuchereria bancrofti microfilariae (mf) and determined the effect of these parasite properties on the accuracy of blood filming and filtration methods for diagnosis of bancroftian filariasis in the endemic area of Recife, Brazil. Microfilariae in both venous and capillary blood exhibited a ...

The study demonstrates weakly to strongly positive reaction staining for NADPH-diaphorase/NO- synthase in the peripheral cells of sebaceous glands in the hairy skin of domesticated mammals. Additionally, the structure of the blood capillary system surrounding these glands is better elucidated. The results obtained are discussed in view of a modulatory ...

The observed positive correlation between cessation of red blood cell flow in capillaries at low perfusion pressures and the oxygen tension (PO2) in the superfusion solution may be due to oxygen-dependent arteriolar constriction. To test this hypothesis, we investigated capillary flow cessation during aortic occlusion and concomitant changes in diameters ...

We examined the effect of hemorrhagic hypotension on cerebral blood flow and perfused capillaries in newborn pigs, 2-10 days old. Cerebral blood flow was measured by using radioactive microspheres, perfused capillaries were determined by infusing a plasma marker, fluorescein isothiocyanate (FITC) - dextran (molecular mass 147,000 Da), and total capillaries ...

The density of the total and the perfused capillary network was determined in the brains of awake, normocapnic rats. Perfused capillaries were marked by i.v. Evans blue. Existing capillaries were made visible by antibodies directed against the fibronectin portion of the capillary walls. Comparison of perfused and existing capillaries in ...

Capillary leakage of a macromolecular contrast agent, Carboxymethyl Dextran-Gd-DTPA (CMD-Gd-DTPA) was characterized in a highly permeable system, the liver, to assess its potential as a blood pool marker. Its elimination kinetics in hepatic lymph were compared in nephrectomized rabbits with that of a tracer of extra cellular fluid space, Gd-DOTA. ...

We undertook this study to determine if pericytes respond to carbon dioxide in a manner such that they could help control capillary blood flow and that their physiologic responses to pCO2 might be worthy of detailed study. Pericytes were isolated from bovine retinas and grown in cell culture. Changes in ...

Based on the variation in the optical density due to erythrocyte concentration and movement, the axial tomographic and image velocimetry techniques are respectively applied to determine the flow field, i.e., the distribution of erythrocytes and axial and radial velocity components, in steady blood flow through a curved glass capillary with ...

The purpose of this study was to evaluate the hemodynamic deterioration in cutaneous microcirculation and its clinical correlation in patients with tetralogy of Fallot (TF). Laser Doppler flowmetry and capillary microscopy were used to assess thermoregulatory and nutritional microcirculation, respectively. A significant increase in blood flow in thermoregulatory vessels was ...

The analytical performance of the new capillary blood prothrombin time monitoring system CoaguChek was examined in a multicenter evaluation at six hospitals. The coefficients of variation of the INR obtained in the CoaguChek imprecision study were approximately 7% in the control plasma provided (within-run and day-to-day) and 4% in blood ...

BACKGROUND: The urinary bladder requires a rich blood supply to maintain its functions, the storage and release of urine. Specialized properties of the bladder vasculature might be anticipated to ensure the integrity of this blood supply, because it is known that blood flow is reduced by distension during bladder filling. ...

A system which couples microdialysis with capillary zone electrophoresis (CZE) on-line is used to monitor ascorbate and lactate in the caudate nucleus of rat brain. On-line interface of microdialysis probe and electrophoresis capillary, along with the high mass sensitivity of CZE, allows the probe to be operated at flow rates ...

The length of time that blood remains in the pulmonary capillary is an important variable in gas exchange. We have investigated the distribution of capillary transit times in isolated rabbit lungs perfused with a bicarbonate-free buffer. The time course of gas exchange was monitored by enclosing the lungs in a ...

The effects of flow heterogeneity on the measurement of transcapillary escape of small molecules for perfused in situ sheep lungs were evaluated. Lungs were studied at five flows (1.5-5.0 l/min) ranging from zone 1 to zone 3 conditions. At each flow, multiple indicator-dilution curves were collected using 14C-labeled urea (U) ...

The role of arterioles and capillaries in microcirculatory gas exchange was evaluated using a multicompartmental model for O2-CO2 transport in the rat skeletal microcirculation. Model predictions were examined to investigate the effects of model formulation and model parameter values. The factors in model formulation included radial blood diffusion resistance, the ...

The resolution in capillary zone electrophoresis (CZE), with the assumption of diffusion control only, is strongly dependent on the direction and magnitude of electroosmotic flow. In fact, excellent separation resolution will be obtained if the electroosmotic flow is in the opposite direction of the electrophoretic migration. By applying various radial ...

In an open placebo-controlled study the influence of the injection of different sonographic contrast media on the microcirculation was proved. The study was performed in 7 Sprague-Dawley rats. In order to examine this query two different sonographic contrast media in comparison to agitated electrolyte solution (as the placebo) were injected ...

To investigate the effects of propofol on small vessels, we have measured changes in diameter and blood flow in microcirculatory venules and arterioles. Studies were carried out in the dorsal skinfold chamber of hamsters by intravital fluorescence microscopy. A bolus injection of propofol 25 mg kg-1 dilated small and collecting ...

To clarify the evolution of acute lung injury induced by endotoxin, the progression of lung damage in 26 rats submitted to intratracheal instillation of 5 mg/kg body weight endotoxin was examined by blood gas analysis, computerized tomography, light and electron microscopy. Hypoxaemia, hypercapnia, acidosis and inhomogeneous bilateral infiltrates developed gradually ...