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PubMed1998

Highly water-permeable type I alveolar epithelial cells confer high water permeability between the airspace and vasculature in rat lung.

Water permeability measured between the airspace and vasculature in intact sheep and mouse lungs is high. More than 95% of the internal surface area of the lung is lined by alveolar epithelial type I cells. The purpose of this study was to test whether osmotic water permeability (Pf) in type I alveolar epithelial cells is high enough to account for the high Pf of the intact lung. Pf measured between the airspace and vasculature in the perfused fluid-filled rat lung by the pleural surface fluorescence method was high (0.019 +/- 0.004 cm/s at 12 degrees C) and weakly temperature-dependent (activation energy 3.7 kcal/mol). To resolve the contributions of type I and type II alveolar epithelial cells to lung water permeability, Pf was measured by stopped-flow light scattering in suspensions of purified type I or type II cells obtained by immunoaffinity procedures. In response to a sudden change in external solution osmolality from 300 to 600 mOsm, the volume of type I cells decreased rapidly with a half-time (t1/2) of 60-80 ms at 10 degrees C, giving a plasma membrane Pf of 0.06-0.08 cm/s. Pf in type I cells was independent of osmotic gradient size and was weakly temperature-dependent (activation energy 3.4 kcal/mol). In contrast, t1/2 for type II cells in suspension was much slower, approximately 1 s; Pf for type II cells was 0.013 cm/s. Vesicles derived from type I cells also had a very high Pf of 0.06-0.08 cm/s at 10 degrees C that was inhibited 95% by HgCl2. The Pf in type I cells is the highest measured for any mammalian cell membrane and would account for the high water permeability of the lung.

Animals↗
PubMed1984

The water permeability of toad urinary bladder. I. Permeability of barriers in series with the luminal membrane.

Antidiuretic hormone (ADH) induces a large increase in the water permeability of the luminal membrane of toad urinary bladder. Measured values of the diffusional water permeability coefficient, Pd(w), are spuriously low, however, because of barriers within the tissue, in series with the luminal membrane, that impede diffusion. We have now determined the water permeability coefficient of these series barriers in fully stretched bladders and find it to be approximately 6.3 X 10(-4) cm/s. This is equivalent to an unstirred aqueous layer of approximately 400 microns. On the other hand, the permeability coefficient of the bladder to a lipophilic molecule, hexanol, is approximately 9.0 X 10(-4) cm/s. This is equivalent to an unstirred aqueous layer of only 100 microns. The much smaller hindrance to hexanol diffusion than to water diffusion by the series barriers implies a lipophilic component to the barriers. We suggest that membrane-enclosed organelles may be so tightly packed within the cytoplasm of granular epithelial cells that they offer a substantial impediment to diffusion of water through the cell. Alternatively, the lipophilic component of the barrier could be the plasma membranes of the basal cells, which cover most of the basement membrane and thereby may restrict water transport to the narrow spaces between basal and granular cells.

Amphotericin B↗
PubMed1982

The water permeability of basement membrane under increasing pressure: evidence for a new theory of permeability.

The water permeability and physical characteristics of the basement membrane (lens capsule) of the crystalline lens of the adult rat have been investigated. The hydraulic conductivity of the basement membrane at low pressure is 50 +/- 9.5 X 10(-12) m s-1 Pa-1 and at high pressure 17 +/- 7.5 X 10(-12) m s-1 Pa-1. This decrease in permeability occurs despite a 75% increase in area of the membrane and a 65% reduction in its thickness. Conventional theories of a membrane possessing pores or of a fibre matrix of filaments of a constant diameter fail to explain the decreasing permeability of the membrane with increasing hydrostatic pressure. The present data suggest that the structure of the membrane is changed by pressure and the coiled filaments of which it is composed are extended as stress is applied to the membrane. If allowance is made both for thinning and for compaction of the membrane and the extension of its area the permeability of the membrane can be predicted satisfactorily at varying pressures. Thus the hydraulic conductivity of basement membrane at a given pressure can be adequately described by the product of a constant and a dimensionless 'deformation coefficient'. This deformation coefficient is equal to the square of the product of the thickness ratio and elongation ratio of the membrane at the given filtration pressure.

Animals↗
PubMed1993

Characterization of the increase in vascular permeability induced by vascular permeability factor in vivo.

1. Vascular permeability factor (VPF) is a protein secreted from a variety of human and rodent tumour and normal tissue cells. In addition to mediating angiogenesis and endothelial cell growth, VPF has been reported to be a potent mediator of increased microvascular permeability in vivo. In this study we have investigated these permeability changes in vivo using a quantitative model of local plasma leakage in rabbit skin. 2. Our results reveal that VPF is a potent mediator of plasma leakage which, in the rabbit, depends on a synergistic interaction with arteriolar vasodilators such as prostaglandin E2. The requirement for an exogenous vasodilator further suggest that VPF does not act to increase blood flow in this model. 3. We show that this response does not require the presence of circulating neutrophils and in this respect is similar to direct-action permeability increasing mediators such as histamine and bradykinin. Similarly, the time course of plasma leakage induced by VPF resembles that of direct-action mediators, where the greatest response occurs over the first 30 min. In contrast, the neutrophil-dependent plasma leakage induced by the active component of zymosan-activated plasma, C5ades arg, was maintained at a similar level over 2.5 h. 4. Further, using mediator antagonists and enzyme inhibitors we demonstrate that the mechanism of action of VPF is not via activation of histamine, kinin, or platelet-activating factor pathways.

Animals↗
PubMed2006

Receptor activator of nuclear factor (NF)-kappaB ligand (RANKL) increases vascular permeability: impaired permeability and angiogenesis in eNOS-deficient mice.

Receptor activator of nuclear factor (NF)-kappaB ligand (RANKL) is emerging as an important regulator of vascular pathophysiology. Here, we demonstrate a novel role of RANKL as a vascular permeability factor and a critical role of endothelial nitric oxide synthase (eNOS) in RANKL-induced endothelial function. RANKL increased the vascular permeability and leukocyte infiltration in vivo and caused the breakdown of the blood-retinal barrier in wild-type mice but not in eNOS-deficient mice. In vitro, it increased endothelial permeability and reduced VE-cadherin-facilitated endothelial cell-cell junctions in a NO-dependent manner. RANKL also led to the activation of Akt and eNOS and to NO production in endothelial cells (ECs). These effects were suppressed by the inhibition of TRAF6, phosphoinositide 3'-kinase (PI3K), Akt, or NOS by genetic or pharmacologic means. Inhibition of the TRAF6-mediated NO pathway reduced EC migration and capillary-like tube formation in response to RANKL. Moreover, the effects of RANKL on ECs sprouting from the aorta, and neovessel formation in both the mouse Matrigel plug assay and corneal micropocket assay, were impaired in eNOS-deficient mice. These results demonstrate that RANKL promotes vascular permeability and angiogenesis by stimulating eNOS by a TRAF6-PI3K-Akt-dependent mechanism. These properties may be relevant to the pathogenesis of angiogenesis-dependent and inflammatory vascular diseases.

Animals↗
PubMed1978

Effect of propranolol on ricinoleic acid- and deoxycholic acid-induced changes of intestinal electrolyte movement and mucosal permeability. Evidence against the importance of altered permeability in the production of fluid and electrolyte accumulation.

Hydroxy fatty acids and bile acids produce both intestinal fluid and electrolyte accumulation and increases in inulin clearance, a parameter of mucosal permeability. The relationship of the changes in mucosal permeability to the production of fluid and electrolyte accumulation is uncertain. These experiments were designed to determine whether the alterations of mucosal permeability produced by ricinoleic acid and deoxycholic acid were related to production of hydroxy fatty acid- and bile acid-induced fluid and electrolyte accumulation in the rat colon. Propranolol (1 mg per 100 g of body weight) administered daily for 3 days inhibited ricinoleic acid- and deoxycholic acid-induced Na and water accumulation. In contrast, propranolol did not affect either the increase in inulin clearance or the decrease in electrical potential difference produced by ricinoleic acid and deoxycholic acid. Further, amphotericin B increased inulin clearance by the colon and also increased water and Na absorption. These studies suggest that changes in mucosal permeability are not primarily responsible for hydroxy fatty acid- and bile acid-induced fluid and Na accumulation.

Amphotericin B↗
PubMed1976

[Permeability-increasing effect of punctates. 3. Inhibition of the permeability-increasing activity by contrykal].

The punctate of the pleural cavity of a patient was examined which very much increased the permeability of the membrane in the animal experiment. Proteases is ascribed the effect increasing permeability, which are adsorbed to macromolecules. The increase of permeability could be inhibited by contrycal. An increase of permeability by proteolytic enzymes is discussed as one of the possible pathomechanisms for the development of exudations.

Animals↗
PubMed1977

Ion permeability and strength of cell contacts: ion permeability and mechanical properties of cell contacts in small intestine epithelium.

The effects of several simple parameters (pH, concentration of bivalent cations, osmotic pressure, and temperature) on the ion permeability and mechanical properties of cell contacts have been investigated. It has been shown that the mechanical properties of a cell contact make it possible to describe it as a viscoelastic system. The main contribution to cell adhesion is made by the tight junction. Two populations of acidic centers have been identified on the cell membrane surface. One population interacts with bivalent cations to assure cell adhesion. The other population of weaker acidic centers regulating ion permeation is involved in the cell membrane's interaction of the repulsion type. An intimate correlation has been established between changes in passive transepithelial ion permeability and cell adhesion in response to changes in pH and in bivalent cation concentration. Such a correlation is possible if the tight junction is the principal contributor to the passive ion permeability and mechanical strength of the cell contacts.

Animals↗
PubMed1989

Densitometric measurement of increased endothelial permeability in arteriosclerotic plaques and inhibition of permeability under the influence of two calcium antagonists.

A densitometric technique was established to investigate quantitative changes in endothelial permeability for horseradish peroxidase (HRP), mol. wt. 40,000 daltons, in rabbit carotid artery. Repeated weak electrical stimulations of rabbit carotid arterial walls with implanted electrodes lead to fibromuscular plaques mainly beneath the anode. It could be demonstrated that there exists a typical growth curve of the plaques dependent on the number of days of electrostimulation, with a fast proliferation rate of smooth muscle cells in the first 2 weeks of electrostimulation, and an increasing retardation of proliferation during the next 4 weeks. Endothelial permeability for HRP increases in close relation to the plaque development. Intravenous applications of single doses of the calcium entry blockers flunarizine or nimodipine are able to inhibit the increased permeability of the endothelial lining covering arteriosclerotic plaques. The intensity of the inhibitory action of these calcium antagonists correlates with the size of the arteriosclerotic plaques in inverse proportion, but nevertheless in large plaques an inhibitory effect is seen.

Animals↗
PubMed1996

Osmotic water permeability of capillaries from the isolated spiral ligament: new in-vitro techniques for the study of vascular permeability and diameter.

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 and for the determination of changes in the diameter of isolated inner ear capillaries. Both techniques rely on measurement of the velocity of marker red cells trapped in the lumen of capillaries. The velocity of marker red cells is a measure for the capillary permeability when a water flux across the capillary wall is induced by an osmotic gradient or a measure for a change in the capillary diameter. With these techniques the osmotic water permeability coefficient (Pf) and the pH sensitivity of isolated capillaries from the spiral ligament of the inner ear was determined. Pf at 23 degrees C was (1.49 +/- 0.17) 10(-3) cm/s at pH 7.4 and (1.61 +/- 0.23) 10(-3) cm/s at pH 6.8 (n = 12: mean +/- SEM: n = number of tissues). Pf at 37 degrees C was (2.26 +/- 0.23) 10(-3) cm/s at pH 7.4 and (2.35 +/- 0.17) 10(-3) cm/s at pH 6.8 (n = 13). No change in capillary diameter was observed when the pH of the interstitial fluid was lowered from pH 7.4 to 6.8. These data demonstrate that Pf and the capillary diameter of spiral ligament capillaries are pH independent and suggest that water crosses the blood-labyrinth barrier via an aqueous pathway. Further, these data suggest that the relatively low Pf is another characteristic shared by the blood-labyrinth and the blood-brain barrier.

Animals↗
PubMed1986

Corneal permeability of aldose reductase inhibitor, M79175. I. In vitro study using corneal permeability apparatus.

Transcorneal permeability of M79175, aldose reductase inhibitor (Eisai), and various factors influencing it were examined using excised rabbit cornea mounted on the methacrylate apparatus. High permeability was exhibited and this was independent of the concentration of M79175. Cornea hydrated by exposure to the eye drop solution of high concentration of benzalkonium chloride, which had an enhancing effect on the permeability of M79175. Corneal hydration was also caused by the solution of low pH. These findings will show the basic conditions for this eye drop solution to be an artificial tear fluid.

Aldehyde Reductase↗
PubMed2005

Electrical parameters and water permeability properties of monolayers formed by T84 cells cultured on permeable supports.

T84 is an established cell line expressing an enterocyte phenotype whose permeability properties have been widely explored. Osmotic permeability (POSM), hydraulic permeability (PHYDR) and transport-associated net water fluxes (JW-transp), as well as short-circuit current (ISC), transepithelial resistance (RT), and potential difference (deltaVT) were measured in T84 monolayers with the following results: POSM 1.3 +/- 0.1 cm.s-1 x 10-3; PHYDR 0.27 +/- 0.02 cm.s-1; RT 2426 +/- 109 omega.cm2, and deltaVT 1.31 +/- 0.38 mV. The effect of 50 microM 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a "net Cl- secretory agent", on T84 cells was also studied. We confirm the reported important increase in ISC induced by DCEBIO which was associated here with a modest secretory deltaJW-transp. The present results were compared with those reported using the same experimental approach applied to established cell lines originating from intestinal and renal epithelial cells (Caco-2, LLC-PK1 and RCCD-1). No clear association between PHYDR and RT could be demonstrated and high PHYDR values were observed in an electrically tight epithelium, supporting the view that a "water leaky" barrier is not necessarily an "electrically leaky" one. Furthermore, the modest secretory deltaJW-transp was not consistent with previous results obtained with RCCD-1 cells stimulated with vasopressin (absorptive fluxes) or with T84 cells secreting water under the action of Escherichia coli heat stable enterotoxin. We conclude that, while the presence of aquaporins is necessary to dissipate an external osmotic gradient, coupling between water and ion transport cannot be explained by a simple and common underlying mechanism.

Cell Line↗
PubMed1992

[Estimation of pulmonary vascular permeability by indocyanine green in permeability pulmonary edema].

In this study we attempted to estimate pulmonary vascular permeability by indocyanine green (ICG). Permeability pulmonary edema was produced in 9 adult dogs by injecting 0.08 ml/kg oleic acid. We injected 50 mg ICG intravenously in 18 dogs (9 dogs with pulmonary edema and 9 control dogs). We measured the time course of ICG concentrations in pulmonary arterial blood, ICG concentration of peripheral lung tissue, tissue/serum ICG concentration ratios, and wet/dry lung weight ratios. The following results were obtained. The time course of ICG concentration in pulmonary arterial blood showed peak values at 2 minutes and became constant at 5 or 10 minutes after injection. The ICG concentration in peripheral lung tissue, tissue/serum ICG concentration ratios, and wet/dry lung weight ratios in the pulmonary edema group were significantly higher than those in the normal group. There was a strong linear correlation between wet/dry lung weight ratio and ICG concentration in peripheral lung tissue, with correlation coefficients of r = 0.936 (p < 0.01) in the right lung and r = 0.901 (p < 0.01) in the left lung. From these results, we conclude that estimation of pulmonary vascular permeability by ICG is a useful method.

Animals↗
PubMed1994

Pulmonary permeability oedema. Methods of estimation of pulmonary capillary permeability.

Lung permeability oedema (acute respiratory distress syndrome-ARDS) is characterized by the increase of microvessels and epithelial permeability. In the estimation of pulmonary capillary permeability, the mathematical modeling is very useful. Some models and practical clinical methods concerning this problem are reviewed in this paper.

Capillary Permeability↗
PubMed1977

Permeability studies on taeniid metacestodes: II. Antibody-mediated effects on membrane permeability in larvae of Taenia taeniaeformis and Taenia crassiceps.

Incubation in immune rat serum (IRS) was shown to increase the rate of absorption of 125I RNase-A but not 125I BSA by larvae of Taenia taeniaeformis and T. crassiceps. This effect required a heat labile factor in serum, and partial activity could be restored in heat-treated IRS by adding normal rat serum (NRS) as a source of complement. In addition, the effectiveness of IRS in altering permeability was shown to be dependent on the concentration of functional complement. Both live and dead larvae incubated in NRS rapidly depleted hemolytic complement levels in the surrounding medium. Immunoglobulin fractions from IRS separated by anion exchange chromatography and and gel filtration were tested in the presence of excess complement for their ability to affect uptake of 125I RNase-A. Enhanced permeability was observed in larvae incubated in each fraction. The results show that antibodies in conjunction with complement are capable of disrupting larval permeability control in vitro. The observation that larvae were able to restore normal control as complement levels declined suggests that the parasites may overcome this immunologic effector mechanism by interfering with complement function.

Animals↗
PubMed1986

Defining the lower limits of blood-brain barrier permeability: factors affecting the magnitude and interpretation of permeability-area products.

Experimental alteration in the restricted permeability of the blood-brain barrier to polar, blood-borne molecules is often quantitated in the rat with use of 14C-sucrose or 3H-mannitol delivered as a test substance into the circulation. The underlying principle is to relate the quantity of saccharide that has permeated into brain parenchyma, after an arbitrary time period, to some index of the circulating tracer level. This study indicates that to correct the radioactivity level in the brain tissue for intravascular tracer, it is an erroneous practice to estimate the latter as the product of tissue blood volume and the tracer concentration measured in a systematic blood sample. Dissected brain tissue was found to have a lower hematocrit and thereby larger plasma/tracer compartment per unit blood volume than femoral arterial blood. It is further shown that, although commercially supplied stocks of 14C-sucrose or 3H-mannitol may contain only small quantities of radioactive impurities, their inclusion in injectates and preferential uptake into brain may cause significant overestimation of permeability to the parent tracer. It is also confirmed that magnitude of permeability-area (PA) products for permeation of purified sucrose or mannitol into brain varies inversely with the length of time allotted for tracer circulation in the bloodstream. This finding is at variance with the assumptions of a two-compartment (plasma/brain) diffusion model underlying such measurements and supports a recently published model for blood-to-brain transfer based on multiple uptake compartments in brain parenchyma. The factors compromising PA measurement identified in this study may partly underlie variations in PA values published from several laboratories that had been attributed to genetic differences in laboratory rats.

Animals↗
PubMed2002

Tacrolimus is a class II low-solubility high-permeability drug: the effect of P-glycoprotein efflux on regional permeability of tacrolimus in rats.

The objective of this study is to investigate the role of P-glycoprotein (P-gp), a membrane efflux pump associated with multidrug resistance (MDR) and a known substrate for tacrolimus, in determining the regional intestinal permeability of tacrolimus in rats. Thus, isolated segments of rat jejunum, ileum, or colon were perfused with tacrolimus solutions containing polyethoxylated hydrogenated castor oil 60 surfactant, and with or without verapamil, a P-gp substrate used to reverse the MDR phenotype. The results indicated that the intrinsic permeability of tacrolimus in the jejunum, calculated on the basis of the concentration of non-micellized free tacrolimus, was quite high ( approximately 1.4 x 10(-4) cm/s). The apparent permeability (P(app)) in the jejunum was unaffected by the presence of verapamil; however, the P(app) in the ileum and the colon increased significantly in the presence of verapamil and were similar to the values observed in the jejunum. The results suggest that systemic absorption of tacrolimus from the gastrointestinal tract could be significantly affected by P-gp efflux mechanisms. It is also possible that differences in P-gp function at various intestinal sites in a subject or at a given intestinal site in various subjects could lead to large intra- and interindividual variability in bioavailability of tacrolimus following oral administration.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Studies of glomerular permeability factor (GPF) in focal segmental glomerular sclerosis and the relationship between GPF and vascular permeability factor (VPF).

BACKGROUND: We previously demonstrated that the supernatants of cultured concanavalin-A (con-A) stimulated peripheral blood mononuclear cells (PBMC) from patients with minimal change nephrotic syndrome (MCNS) increased the urinary protein excretion in injected rats and suggested that PBMC released a factor, which we called glomerular permeability factor (GPF), changes in the glomerular permeability and thus resulted in proteinuria in MCNS. MATERIAL AND METHODS: In this study we investigated the GPF activity in focal segmental glomerular sclerosis (FGS) and other conditions of chronic glomerulonephritis (CGN), and also the relationship between GPF and vascular permeability factor (VPF). In experiment 1 the supernatants of the cultured con-A stimulated PBMC from patients with 10 FGS, 5 other CGN and 10 controls were tested regarding their ability to produce GPE The GPF activity was defined as positive when the 8-hour urinary protein excretion after the injection of the supernatant in Sprague-Dawley rats exceeded the mean value plus 2 standard deviations (M + 2 SD) of that before injection. RESULTS: Three out of 10 FGS patients and 1 membranous nephropathy patient out of the 5 other CGN patients were positive for GPF activity. In experiment 2 the relationship between GPF and VPF was analyzed using culture supernatants of PBMC from 10 nephrotic MCNS patients and 15 controls. The VPF activity was measured following the method developed by Ovary [1975]. All 7 cases that were positive for GPF activity were simultaneously positive for VPF activity. On the other hand, 16 cases that were positive for VPF activity were not always positive for GPF activity (7 cases were positive and 9 were negative for VPF activity). CONCLUSION: Experiments 1 and 2 thus suggested that GPF was not active in MCNS alone, but also in other CGN conditions and it was therefore not considered to be the same factor/substance(s) as VPF.

Adolescent↗