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PubMed1980

Model analysis of transcapillary exchange: the role of cyclotron produced isotopes in the study of the capillary permeability of substances.

The purpose of this paper is to review different models used in the interpretation of capillary permeability studies using tracer dilution methods, with special emphasis on the role of cyclotron-produced isotopes. The physical model is a simplified description of the biological system, and the mathematical formalism is a device by which the model and experimental data can be compared. If there is a correlation and the solution is unique and consistent, the model is considered acceptable. Capillaries--the end organs of the circulatory system--are physiologically important because they are the site for the exchange of materials (oxygen, glucose, waste products etc.). The positive and negative findings in radionuclide imaging studies are caused by changes in capillary permeability. The indicator diffusion methods have many advantages over the conventional compartmental analyses. The diffusion models take into account the normal histological structure of the tissue and it is possible to get information about both capillary and cellular physiology. Short-lived, cyclotron produced positron emitting radionuclides, carbon-11, nitrogen-13, oxygen-15 and fluorine-18, are suitable for the study of transcapillary exchange.

Capillary Permeability↗
PubMed1995

Transmigration of fluid rapidly infused into dogs with renal blood vessels ligation and increased pulmonary capillary permeability.

To study the transmigration of fluid rapidly infused intravenously, lactated-Ringer's solution was infused at the rate of 90 ml/kg/hr for 30 min into generally anesthetized dogs. Four groups were made; group C with no fluid infusion as the control, group F with rapid fluid infusion only, group LF with renal blood vessels ligation and rapid fluid infusion, and group OF with increased pulmonary capillary permeability experimentally induced by oleic acid and rapid fluid infusion. The extravascular lung water volume (ELWV) was measured by the thermal-sodium double indicator dilution method, and the amounts of ascites and urine, and other clinical parameters were monitored before and after fluid infusion. The results show that in the dogs without increased pulmonary capillary permeability excessive fluid is mainly excreted as urine (group F) or transudates into the abdominal cavity (group LF). But in the dogs with increased pulmonary capillary permeability (group OF) excessive fluid easily and rapidly transudated into the pulmonary interstitium, resulting in pulmonary edema.

Animals↗
PubMed1985

[Electron microscopic research on the capillary permeability of the primary portal plexus in rats in the prenatal period].

Permeability of portal capillaries to intravascularly injected ionic lanthanum, ferritin and horse-radish peroxidase has been examined in rats on the 18th fetal day, and on days 1 and 9 of postnatal life. For several minutes, tracer molecules pass through the capillary wall and reach the median eminence. In the case of immature capillaries, the materials pass freely through the endothelial cells, and to a lesser extent are transferred via occasional plasmalemmal vesicles and fenestrae. As the maturation of capillaries proceeds their permeability via plasmalemmal vesicles and fenestrae increases considerably due to a gradual rise in the number of these structures. The plasmalemma of differentiated endothelial cells becomes impermeable to all the tracers. Only ionic lanthanum appears to penetrate through transendothelial channels and intercellular junctions between adjacent endothelial cells.

Animals↗
PubMed1981

Effects of transfusion of emboli and aged plasma on pulmonary capillary permeability.

The effects of transfusion of whole blood clot emboli and aged citrated platelet-poor plasma on pulmonary capillary permeability were investigated in anesthetized sheep by continuous collection of pulmonary lymph. Changes in lymph flow and lymph-to-plasma ratios (CL/CP) for albumin and globulin were utilized to detect changes in permeability. Infusion of 0.5 cc/kg of finely (less than or equal to 1 mm) diced autologous whole blood clot resulted in a 170% increase in lymph flow over control with no change in CL/CP for albumin or globulin. Infusion of 1 cc/kg of autologous clot increased lymph flow 180% over control and increased CL/CP for albumin and globulin. Infusion of homologous platelet-poor plasma caused greater increases in lymph flow without changes in CL/CP. Changes in each of these three groups were consistent with increased permeability. Balloon occlusion of one main pulmonary artery was induced without a fall in cardiac output and resulted in no change in lymph flow of CL/CP despite a rise in pulmonary vascular resistance (PVR). Femoral arteriovenous fistulas were created to increase cardiac output, but no change in lymph flow or CL/CP occurred. The results in these latter two experiments suggest that increased perfusion per unit lung capillary bed or increased PVR were not primarily responsible for the changes observed in the emboli-treated and plasma-infused animals. Since both emboli and aged platelet-poor plasma increased pulmonary capillary permeability, the permeability increasing factor appears to be humoral in origin. Similar humoral factors may be important in the pathogenesis of the adult respiratory distress syndrome in man.

Albumins↗
PubMedDate not supplied

Testicular capillary permeability: the movement of luteinizing hormone from the vascular to the interstitial compartment.

It has previously been shown in several species that pulses of luteinizing hormone (LH) in peripheral serum are followed within 10-20 minutes by pulses of testosterone. Whether or not LH pulses directly stimulate Leydig cells to produce the testosterone pulses would depend on the vascular permeability of LH within that physiologically relevant time. In the present experiments, the capillary permeability of the testicular microvasculature was characterized in adult rats, and the relative permeability to LH was determined. Adult male rats were prepared for in vivo micropuncture and testes were infused with 3H-water, 14C-urea, 14C-polyethylene glycol (PEG), and 3H-dextran directly into the testicular surface artery. Testicular interstitial fluid (TIF) and testicular venous plasma were collected at 5 minutes, 10 minutes, and 15 minutes after initiation of isotope infusion. Data were recorded as isotope concentration in TIF as a proportion of the isotope concentration in testicular venous plasma collected at the same time period. 3H-water movement into the TIF from blood was rapid reaching 50% of serum values within 15 minutes. 14C-PEG and 3H-dextran were largely excluded from the TIF, typically not exceeding 5-10% of serum concentrations. In subsequent experiments, 125I-LH was infused using the same protocol. 125I-LH concentrations in TIF were 3.6 +/- 2.0% of plasma concentrations 10 minutes after initiation of infusion. Preceding the 125I-LH infusion experiments with 5-day hypophysectomy or with LH pulses delivered either 10 minutes or 4 hours prior to the initiation of infusion did not alter the capillary permeability of 125I-LH. These data demonstrate the restricted availability of LH to the TIF. This implies that Leydig cells are not exposed to LH pulses through the TIF and raises the question whether LH pulses directly stimulate testosterone pulses.

Animals↗
PubMed1985

Capillary permeability of 131I-albumin in skeletal muscle.

Capillary permeability of 131I-albumin in skeletal muscle was determined by applying the "single injection, residue detection" method to the autoperfused cat gastrocnemius muscle preparation. Experiments at zero venous pressure gave an average capillary extraction fraction, E, of 0.028 at a plasma flow of about 3 ml X (100 g)-1 X min-1. The permeability-surface area product, PS, was on average 0.075 ml X (100 g)-1 X min-1. Experiments at a venous pressure of 10 mm Hg gave essentially the same PS product (0.070 ml X (100 g)-1 X min-1. Further experiments demonstrated that stagnant intravascular pools of 131I-albumin were not present. The free diffusion coefficient in water at 37 degrees of the purified 131I-albumin was 0.0631 X 10-5 cm2 X sec-1). The distribution volume for 131I-albumin in the interstitial space was 3.5 ml X (100 g)-1 X sec-1. Assuming a capillary surface area of 70 cm2 X g-1 the permeability coefficient was calculated to be 18 X 10(-8) cm X sec-1 which is about 3 to 10 times higher than values obtained by lymph sampling methods. The results indicate that the predominant transcapillary transport mechanism for 131I-albumin is diffusion. When analyzed according to the theory of restricted diffusion the results are compatible with transcapillary diffusion through pores with an effective equivalent pore radius of 145 A.

Albumins↗
PubMed1995

The effects of metformin on the capillary permeability to albumin in women patients with cyclic edema.

An experimental work has suggested the efficacy of metformin, an oral antidiabetic agent, on capillary permeability. This agent has been tested in 10 women patients with cyclic edema, 7 of them being obese. The capillary permeability to albumin studied by an isotope test derived from Landis's method was initially increased. After a mean of six-weeks of treatment the albumin retention and an index demonstrating the interstitial protein elimination through the lymph route were significantly improved. Concomitantly, the swelling feelings were reduced in 8 cases and the lower limb edema had decreased or disappeared in 8 of 9 patients who initially presented these symptoms. The effects of metformin are beneficial and have been observed to be independent of glycemic change. The results suggest a special effect of this agent on the microcirculation. Nevertheless, a controlled study is required.

Adult↗
PubMed2004

Abnormal capillary permeability and endothelial dysfunction in hypertension with comorbid Metabolic Syndrome.

PURPOSE: Metabolic Syndrome as defined by ATP III criteria, a constellation of risk factors associated with insulin resistance, predisposes to premature atherosclerosis and early coronary events. Whether that negative risk profile is associated with endothelial dysfunction remains to be established. MATERIALS AND METHODS: Transcapillary escape rate of albumin (TERalb), a measure of capillary permeability and integrity of systemic capillary endothelium, and forearm vasodilation to intra-arterial acetylcholine (ACH), an index of nitric oxide (NO)-mediated vasomotor dysfunction, were assessed in 24 non-diabetic, uncomplicated hypertensive men with Metabolic Syndrome according to ATP III criteria (hypertension with at least two additional traits such as high triglycerides, low HDL, abdominal obesity, impaired fasting or post-load plasma glucose). Twelve age-matched lean normal hypertensive patients with normal lipid and glucose profile and nine normotensive subjects were the controls. All patients underwent lipids determination and fasting and post-OGTT insulin assessment; HOMA-IR was the index of insulin resistance. RESULTS: TERalb was higher in hypertensive patients with Metabolic Syndrome, without differences between hypertensive and normotensive controls. Blood pressure (BP), lipids, plasma glucose, insulin levels and HOMA-IR were unrelated to TERalb. Responses to acetylcholine were selectively attenuated in metabolic patients and, on an individual basis, related only to HDL cholesterol levels, independent of LDL cholesterol, BP, body size, triglycerides, and HOMA-IR values. No relationship existed between responses to acetylcholine and TERalb. CONCLUSIONS: Altered systemic capillary permeability characterizes insulin-resistant hypertensive patients with Metabolic Syndrome. That defect, which may promote early atherosclerosis development, coexists with blunted endothelial-mediated vasodilation, indicating a pervasive abnormality of endothelial function.

Acetylcholine↗
PubMed2001

Effect of the aqueous extract of Rumex patientia on xylol and hyaluronidase induced capillary permeability compared to indomethacin.

In this study, the effect of an aqueous extract of Rumex patientia L. (Polygonaceae) (D-1) on capillary permeability which was induced by xylol and hyaluronidase was investigated. Experiments were conducted on rabbits according to Monakova and Matusis methods. The effects of D-1 were compared to those of indomethacin, which was used as a control throughout the experiment. Both D-1 (100 mg/kg) and indomethacin (10 mg/kg) were administered orally. As a result, D-1 inhibited capillary permeability, which was induced by xylol and hyaluronidase, and it was found that it was as effective as indomethacin.

Animals↗
PubMed2000

Alterations in capillary permeability in the lower limb of patients with chronic critical limb ischaemia and oedema.

BACKGROUND: Oedema formation in lower limbs of patients with chronic critical limb ischaemia (CLI) is a common clinical feature. The rate of fluid filtration through the capillary wall depends on the capillary permeability, i.e. capillary filtration coefficient (CFC). In order to elucidate the pathogenesis of this ischaemic oedema, CFC was measured in the limbs with CLI and oedema and was compared with CFC measurements both in the contralateral sides and in the lower limbs of a control group. PATIENTS AND METHODS: Eleven women and 4 men, with a mean age of 75 +/- 8.8 years, with unilateral CLI and leg and foot oedema were included. Leg and foot volume was measured with water displacement volumetry (WDV). CFC was measured in both limbs by strain-gauge plethysmography using a double-stranded mercury in silicone strain gauge around the middle portion of the foot. As a control group, 8 patients, 5 women and 3 men, with a mean age of 77 +/- 7.6 years with a proximal femur fracture were included and the CFC in this group was measured in the foot of the non-fractured limb. RESULTS: Mean CFC in the limbs with CLI and oedema was 0.0036 +/- 0.001 ml/min.100 ml.mmHg, significantly greater than both the contralateral limbs (0.0019 +/- 0.0003 ml/min.100 ml.mmHg, p < 0.01) and mean CFC in the control limbs (0.0017 +/- 0.0002 ml/min.100 ml.mmHg, p < 0.003). There was a mean volume difference of 13 +/- 9% between limbs with CLI and contralateral sides measured by WDV. There was no significant correlation between total leg-foot volume and CFC (p > 0.05). CONCLUSION: CFC in the ischaemic limb was twice as great as both the contralateral side and the limbs of the control group. It is therefore concluded that an increased CFC is probably one of the important factors in the development of this ischaemic oedema.

Aged↗
PubMed1992

Effect of substance P and Sar9Met(O2)11-substance P on cutaneous capillary permeability in guinea pig skin.

The purpose of this study was to assess the effect of several drugs on the increase in cutaneous capillary permeability induced by intradermal injection of substance P (SP) and Sar9Met(O2)11-SP in guinea pig skin. On the one hand, the increase in cutaneous capillary permeability was partly reduced by spantide, promethazine, atropine or SR 40037, an inhibitor of the angiotensin-converting enzyme. On the other hand, norepinephrine and B3824, a B2-antagonist of bradykinin, showed an enhancing effect. Our results suggest that the effect of SP and Sar9Met(O2)11-SP in guinea pigs is partly mediated by histamine and acetylcholine, and that there is a relationship between tachykinins and bradykinin.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

[Effect of tranilast, an anti-allergic drug, on carrageenin-induced granulation and capillary permeability in rats].

We studied the effect of tranilast on the growth of carrageenin-induced granulation and the increase in capillary permeability induced by inflammatory agents in rats. In the carrageenin-induced granulation model, tranilast (50 or 100-200 mg/kg, p.o.) decreased significantly and dose-dependently the weight and the hydroxyproline content of the granulation tissue. Tranilast, however, showed no effect on the healing day of locally wounded dorsal skin of rats. Triamcinolone (10 mg/kg, p.o.) also showed an inhibitory effect on the carrageenin-induced granulation model. Tranilast (50-400 mg/kg, p.o.) dose-dependently inhibited the enhancement of capillary permeability induced by the Ca ionophore A23187, bradykinin and xanthine oxidase. Moreover, tranilast (30 and 300 microM) suppressed superoxide production induced by FMLP in human neutrophils, but did not act as a superoxide scavenger. Considering that hypertrophic scar and keloid are conditions characterized by abnormal cell proliferation and excessive collagen accumulation accompanied with itch and pain, these results suggest that tranilast is useful as a therapeutic drug for hypertrophic scars and keloids.

Adult↗
PubMed1993

Measurement of capillary permeability to macromolecules by dynamic magnetic resonance imaging: a quantitative noninvasive technique.

A simple, linear kinetic model has been developed for the noninvasive assessment of capillary permeability to macromolecules in the rat by dynamic magnetic resonance imaging using albumin-Gd-DTPA. Data required by the model are signal intensity responses from a target tissue and a venous structure such as inferior vena cava before and after bolus intravenous injection of albumin-Gd-DTPA. Additional requirements include an early temporal resolution of approximately one image/min and a blood sample for hematocrit. The model does not require measurement of albumin-Gd-DTPA concentration in either arterial or venous blood. Pilot experiments suggest that this technique is adequate for estimation of the fractional leak rate of macromolecules from plasma to interstitial water as well as tissue plasma volume, the product of which yields a measure of the permeability surface area product of the tissue if the extraction fraction is modest (< 0.2). The technique may be generally applicable to the study of abnormal capillary permeability in humans as well as animals.

Algorithms↗
PubMed1985

[Hypovolemic shock caused by increased capillary permeability associated with monoclonal gammopathy. New case and review of the literature].

The authors report another case of hypovolaemic shock due to increased capillary permeability and review previous reports in the medical literature. It is a rare condition with all patients presenting hypovolaemic shock of sudden onset with varying degrees of hypoproteinaemia and increased haematocrit. A monoclonal globulin peak is usually observed on serum electrophoresis during and between episodes of shock. The pathological role of this globulin in the increased capillary permeability has not been established.

Capillary Permeability↗
PubMed1992

[Study on the capillary permeability of myocardium in diabetic rats].

The alteration of myocardial capillary permeability (MCP) in experimental diabetic rat was investigated by using cationic ferritin as a tracer. Diabetes was induced by injection of streptozocin (70mg/kg b.w.ip.). Vehicle injected, age and body weight-matched rats were served as the controls. The myocardial tissue was examined by the end of 2,7, and 9 months or even longer after diabetes induction. Results showed that (1) MCP was significantly increased in diabetic rats in comparing with that of the controls; (2) The increase of permeability became more pronounced with prolongation of the course of diabetes; and (3) the increase of MCP preceded the capillary basal laminar thickening demonstrated by electron microscopy. These findings suggest that increased MCP may play a role in the pathogenesis of basal laminar thickening and myocardial complications in diabetic state.

Animals↗
PubMed1974

Capillary permeability to protein as a factor in the control of plasma volume.

1. Measurements of plasma volume, blood volume, extracellular fluid volume and capillary permeability to albumin were made in rats before and after plasmapheresis extending over 2 days.2. In spite of a mean reduction of albumin concentration of nearly 40%, plasma volume showed a significant increase of 12%. There was a slight increase in blood volume and a slight decrease in extracellular fluid volume but these changes were not statistically significant.3. The mean capillary permeability to albumin was significantly lower after plasmapheresis than before and changes in permeability showed a strong negative correlation with changes in plasma volume. The possibility of a causal relationship is discussed.

Animals↗
PubMed1981

Alterations of myocardial capillary permeability by albumin in the isolated, perfused rabbit heart.

1. Capillary permeability-surface area products for 22Na, 51Cr-EDTA (mol. wt. 357), [57Co]cyanocobalamin (mol. wt. 1353) and 125I-labelled insulin (mol. wt. approximately or equal to 6000) were measured using the single-passage, multiple-tracer dilution technique in isolated rabbit hearts perfused at constant flows between 0.2 and 4.7 ml. min-1 . g-1. 2. In hearts perfused with a Krebs-Ringer solution containing bovine albumin (10 g . l . -1), the permeability-surface area products for 51Cr-EDTA and [57Co]cyanocobalamin increased as the perfusion rate increased, but reached constant values at flows above 2 ml . min-1 . g-1. For 125I-labelled insulin a diffusion-limited value of 0.06 +/- 0.02 ml . min-1 . g-1 (mean +/- S.E., n = 10) was measured at significantly lower perfusion rates. As the value for 22Na increased continuously with increments in flow, only a flow-limited value could be estimated. 3. When hearts were initially perfused with albumin (10 g . l . -1) and then with an albumin-free Krebs-Ringer solution, a significant increase in the permeability-surface area for 22Na, 51Cr-EDTA and [57Co]cyanocobalamin was observed. 4. In hearts perfused with albumin capillary permeability coefficients calculated for 22Na, 51Cr-EDTA. [57Co]cyanocobalamin and 125I-labelled insulin were respectively: 10.5, 3.5, 2.1 and 0.21 x 10(-5) cm.sec-1. 5. These findings confirm that bovine albumin reduces the permeability of myocardial capillaries to hydrophilic solutes of varying molecular sizes and this effect may be the result of an interaction of albumin with the pathways for transcapillary exchange.

Animals↗