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At least 73 records · Page 4Linked to original sources
PubMed1980

Effect of papaverine on regional cerebral blood flow and small vessel blood content.

The effect of intravenous infusion of papaverine HCl, (2.0-2.5 mg/kg) on regional cerebral blood flow and small vessel blood content in anesthetized rats was determined. Cerebral blood flow was measured in the cerebral cortex, diencephalon plus midbrain, cerebellum, pons and medulla by means of the uptake of iodo[14C]antipyrine. Small vessel blood content was determined by labelling the plasma siderophilin with 59FeCl3. Cerebral blood flow showed interregional variation under control conditions. Papaverine increased flow in all regions, but the effect was greater in the hind compared to the forebrain. Papaverine did not significantly alter small vessel blood content or calculated open capillary density, indicating it had no functional effect upon cerebral precapillary sphincters, and therefore only affected cerebral arterioles.

Animals↗
PubMed1980

Effects of carbon monoxide or low oxygen gas mixture inhalation on regional oxygenation, blood flow, and small vessel blood content of the rabbit heart.

The effects of lowering arterial O2 content, approximately 30%, by inspiration of low O2 or CO gas mixtures on regional myocardial relative tissue PO2, perfusion and small vessel blood content were studied in anesthetized, thoracotomized New Zealand white rabbits. Relative tissue PO2 and perfusion were determined polarographically. 59FeCl3 was used to determine small vessel blood content. In control, relative tissue PO2, perfusion and small vessel blood content averaged 33.1 mm Hg, 64.9 ml/min/100 g and 4.3 ml/100 g respectively in the subepicardium (EPI) and 22.7, 53.6 and 4.2 in the subendocardium (ENDO) of the left ventricle. Both hypoxic conditions increased regional blood flow, but to a lesser extent in the ENDO. Relative ENDO tissue PO2 fell more markedly than EPI in both conditions. Small vessel blood content increased more with CO than low O2. Regional O2 consumption, calculated by Krogh analysis, increased under both conditions. The response to lowered O2 content is thus an increase in flow, metabolic rate and the number of open capillaries with a lowered driving pressure for O2. The effects of these types of hypoxia appear more severe in the ENDO.

Animals↗
PubMed1997

Endothelium-smooth muscle interactions in blood vessels.

1. Blood vessel tone is determined both by smooth muscle and endothelial functions. In coronary arteries taken from rat (Fisher-Lewis) cardiac transplanted hearts, the inducible form of NOS (iNOS) in smooth muscle is more active, while acetylcholine-induced nitric oxide production in the endothelium is greatly diminished. This causes a greatly reduced myogenic constriction, in pressurized septal arteries taken from immunologically challenged transplanted hearts. 2. The sarcoplasmic reticulum (SR) of smooth muscle and the endoplasmic reticulum (ER) of endothelial cells sequester Ca2+ from the cytoplasm. This reduces the intracellular concentration of free Ca2+, which is necessary for the activation of cellular processes. The release of Ca2+ from internal stores occurs through ryanodine and IP3 recoptors located on the SR membrane. 3. The superficial SR/ER also interacts with ion exchangers and pumps in the plasma membrane. This allows for the superficial SR/ER to function in Ca2+ extrusion; for example, inhibition of the SR/ER Ca(2+)-ATPase (SERCA) partially inhibits the rate of loss Ca2+ from the cell. Recent data suggest that the SR Ca(2+)-ATPase and the Na(+)-Ca2+ exchanger of smooth muscle cells function in series; that is, Ca2+ uptake by the SR followed by release towards the exchanger to mediate extrusion. This interaction between the SERCA of the superficial SR and ion exchangers and pumps creates intracellular Ca2+ gradients. 4. The SERCA of the superficial, peripherally distributed SR/ER also serves to regulate Ca2+ entry from the extracellular space. This occurs in part by inhibition of the superficial buffer barrier function of the SR as well as by depletion of stimulated Ca2+ entry. 5. Ca2+ entry is also regulated in endothelial and smooth muscle cells by the membrane potential. Membrane hyperpolarization increases the driving force for Ca2+ entry into endothelial cells, which lack voltage-gated Ca2+ channels, and reduces open state probability of voltage-gated Ca2+ channels in vascular smooth muscle cells. The two cell types have electrical contact and interact in a dynamic manner to regulate blood vessel diameter.

Animals↗
PubMed2005

Common mechanisms of nerve and blood vessel wiring.

Blood vessels and nerve fibres course throughout the body in an orderly pattern, often alongside one another. Although superficially distinct, the mechanisms involved in wiring neural and vascular networks seem to share some deep similarities. The discovery of key axon guidance molecules over the past decade has shown that axons are guided to their targets by finely tuned codes of attractive and repulsive cues, and recent studies reveal that these cues also help blood vessels to navigate to their targets. Parallels have also emerged between the actions of growth factors that direct angiogenic sprouting and those that regulate axon terminal arborization.

Animals↗
PubMedDate not supplied

Interaction between oxygen and the blood vessel wall.

Blood vessels in vivo respond to changes in the supply of oxygen relative to its demand. Whether the vessels which participate in such vasoregulatory responses are directly affected by oxygen remains an open question. Most studies of oxygen sensing by blood vessels have been carried out on strips, rings or segments isolated from relatively large vessels. These preparations are generally sensitive to oxygen from 0 mm Hg to some upper PO2 (10 to 240 mm Hg) whose value depends on experimental conditions. It appears unlikely that reduced energy production secondary to tissue hypoxia is directly responsible for the relaxation usually observed when PO2 is lowered below a critical value. Evidence that an oxygen-linked chemical mediator such as adenosine or prostacyclin is involved in contractile responses to lowered PO2 has been obtained. The site of action of oxygen could be anywhere within the vascular wall, but current evidence suggests a prominent role for the endothelial cells. At present extrapolation of these results to resistance vessels in vivo must be carried out with caution due to potential differences in the behaviour of microvessels relative to large vessels.

Adenosine↗
PubMed1992

Pathways of macromolecular tracer transport across venules and small veins. Structural basis for the hyperpermeability of tumor blood vessels.

BACKGROUND: Blood vessels supplying tumors are hyperpermeable to macromolecules, but the mechanisms responsible are poorly understood. EXPERIMENTAL DESIGN: To investigate the structural basis for the leakiness of tumor blood vessels, we performed a transmission electron microscopic study of three syngeneic transplantable carcinomas (mouse ovarian carcinoma and the line 1 and line 10 bile duct guinea pig carcinomas) at early intervals after intravenous injection of several macromolecular tracers. Tracers with widely differing physical properties were studied: horseradish peroxidase, ferritin, 150 kilodalton fluorescein isothiocyanate-dextran and gold-bovine serum albumin. RESULTS: All tracers leaked primarily from venules and small veins at the tumor-host interface, for the most part vessels lined by a continuous endothelium. The predominant pathway by which all four tracers exited venules in all three tumors was by way of a system of smooth membrane-bound, interconnecting vesicles and vacuoles; these tended to cluster together at irregular intervals in the endothelial cell cytoplasm to form organelle-like structures, vesiculo-vacuolar organelles (VVO). In favorable sections, VVO interfaced with both the luminal and abluminal surfaces of endothelial cells. HRP alone crossed venules and small veins through apposed inter-endothelial cell junctions. Tracers also exited vessels by way of endothelial fenestrae where these occurred (rarely) in mouse ovarian tumor-associated venules. VVO occurred with similar frequency and complexity in the continuous endothelium-lined venules and small veins that supplied the normal subcutis of either tumor-bearing or control animals. As in tumor-associated vessels, VVO provided the predominant pathway by which all four tracers exited normal vessels, but VVO labeling and extravasation were both much greater in tumor than in control vessels (p < 0.001 for ferritin). CONCLUSIONS: VVO are prominent structures in both tumor-supplying and control vessel endothelial cells and provide the primary pathway for macromolecular extravasation. The large increase in permeability characteristic of tumor vessels is likely attributable to upregulation of VVO function.

Animals↗
PubMed1994

[Trial for assessment of values: normal, threatening, and pathologic parameters of acid-base equilibrium in umbilical vessel blood and capillary blood in newborns].

A prospective study in 33 newborns infants born spontaneously at term was carried out. First stage labour duration was up to 10 hours while the second one was no longer than 60 minutes. The key criterion for newborns selection from physiological deliveries was a normal heart rate baseline throughout the whole period of labour. Acid-base parameters in umbilical blood vessels and capillary blood were performed on an Blood Analyzer Corning 168. The results allowed to define normal and pathological ranges of the analysed indicators. They may be used for evaluation of newborn's postnatal conditions.

Acid-Base Equilibrium↗
PubMed2004

Invasion of blood vessels as significant prognostic factor in radically resected T1-3N0M0 non-small-cell lung cancer.

OBJECTIVES: Radical resection is the therapy of choice in non-small-cell lung cancer (NSCLC). However, even in early stages (T1N0, T2N0) up to 35% of patients will experience recurrence. The aim of this retrospective study was to evaluate the prognostic influence of lymph vessel or blood vessel invasion in N0 patients. METHODS: A total of 72 patients (male, 49; female, 23; median age 59; range 40-72) with NSCLC entered the study. The stages were T1-3N0 (T1, 25; T2, 41; T3, 6). Thirteen pneumonectomies and 59 lobectomies or bilobectomies with systematic lymphadenectomy and R0 resection were performed. Histologically, 24 adenocarcinomas, 31 squamous cell carcinomas and 14 subtypes of large cell carcinoma were found. In 22 cases microscopic invasion of the lymphatic vessels and in 11 invasions of blood vessels were found. Six patients showed invasion of either structure. RESULTS: The patients were followed up for at least 5 years or until death. During the follow-up period 27 patients died (21 because of recurrence and 6 because of diagnosis not related to NSCLC). The 5 years overall survival amounted to 62.5%. In cases with invasion of the blood vessels the survival rate was 23.5%, in cases without invasion 74.5% (P< or = 0.01), whereas lymph vessel invasion had no significant impact on survival. Multivariate analysis covering T stages, histological subtypes, location of the tumor, grading, age, sex, and invasion of the lymphatic or the blood vessels showed invasion of the blood vessels as the only factor with significant prognostic impact in the study population. CONCLUSIONS: In resectable N0 patients with NSCLC the microscopic invasion of blood vessels should be considered as an additional prognostic parameter.

Adult↗
PubMedDate not supplied

Characteristics of pulsatile blood flow through the curved bileaflet mechanical heart valve installed in two different types of blood vessels: velocity and pressure of blood flow.

The aim of this study was to investigate the flow fields of blood flowing through the curved bileaflet mechanical heart valve. A numerical analysis was carried out with the fluid-structure interaction between the blood flow and the motion of leaflets in two different types of blood vessels (type A, with sinus blood vessel, and type B, without sinus blood vessel). When the leaflet was fully opened, a fluttering phenomenon was detected in association with the blood flow, and recirculation flows were observed in the sinus region of the blood vessel for type A. During the closing phase, regurgitation was formed between the ring and the edge of the each leaflet for both types. When the leaflet came into contact with the valve ring at the end of the closing phase, rebound of the leaflet occurred. In consideration of the entire domain, the pressure drop occurs mainly in the valve region. The present results showed tendencies similar to those obtained by previous experiments for blood flow and contribute to the development of the curved bileaflet mechanical heart valve prostheses.

Bioprosthesis↗
PubMed1984

Relationship between chromaffin cells and blood vessels in the rat adrenal medulla: a transmission electron microscopic study combined with blood vessel reconstructions.

The rat adrenal medulla architecture was examined using a combination of medullary blood vessel reconstructions and transmission electron microscopy. The peripheral radicles of the central vein and the medullary capillaries of the medullary arteries were thus precisely identified in the electron microscopic observations. The observations confirmed that the peripheral segments of the central vein were sinusoidal vessels with an attenuated and fenestrated endothelial wall. No ultrastructural differences were observed between segments lined by epinephrine-storing cells and those lined by norepinephrine-storing cells. The findings suggest that these peripheral segments of the adrenal central vein were sites of cortical hormonal effects on the adrenal medulla. The vessel structure does not support the hypothesis that medullary chromaffin-cell development is controlled by selective distribution of adrenal blood vessels.

Adrenal Medulla↗
PubMed2003

Blood vessels of the rat tail: a histological re-examination with respect to blood vessel puncture methods.

The rat tail vascularization is histologically re-examined especially with respect to blood sampling and vascular-injection methods. The terminal third of the tail is recommended for blood vessel puncturing. In this segment, the arteries and veins are most prominent, since the structures of the musculo-skeletal system diminish towards the tip of the tail. In addition to the commonly-known blood vessels (one ventral artery, two lateral veins), there is a dorsal vein in the rat tail that is well suited for puncture and cannulation.

Animals↗
PubMed1986

Generation of leukotrienes from fetal and neonatal porcine blood vessels.

Various blood vessels from fetal and neonatal piglets were challenged with calcium ionophore A23187, to examine the release of leukotriene-like material. All tissues released as much or more leukotriene (LT) than adult porcine tissues previously examined. The release fell with increasing gestational age. The release from the intra-abdominal umbilical vein at 11 days preterm (480 ng of LTD4-like activity per gram of tissue) was an order of magnitude higher than that previously observed. The implications with regard to control of the fetal circulatory pattern are discussed.

Animals↗
PubMed2004

[The numerical simulation of pulsatile flow in a tapered blood vessel].

The tapered blood vessel is associated with the human physiological pulsatile blood flow in this study to address the questions about the developing flow. The geometry model of tapered blood vessel, theoretical models of blood flow, physiological boundary conditions and calculation conditions are proposed. An average blood flow function is established according to the physiological pulsatile flow conditions. The pulsatile flow in a 3-D tapered blood vessel is simulated numerically with the flow function. The distributions of velocity and pressure on different time of the cardiac cycle are obtained. The numerical simulation outcomes are compared with the experimental and analytical results. The characteristics of the pulsatile flow in a tapered blood vessel are discussed in this paper.

Blood Circulation↗