An analysis of the permeability of a fenestra

Levick, J. R.; Smaje, L. H.

doi:10.1016/0026-2862(87)90020-3

Cited by 121 publications

(74 citation statements)

References 39 publications

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“…22,23 Rostgaard and Qvortrup 28 clearly demonstrated filamentous sieve plugs, which presumably consist of proteoglycans and contribute to impermeability of glomerular capillary wall to plasma proteins at nondiaphragmed fenestrae of GEnC. For visualization of the sieve plug, they used a new fixative containing oxygen-carrying blood substitute and a contrast enhancement method with K 3 [Fe(CN) 6 ], tannic acid, and uranyl acetate. In this study, we were able to improve visibility of endothelial diaphragms containing PV-1 by the use of tannic acid and uranyl acetate as contrast enhancers; however, our simple method was not capable of visualizing the sieve plug at nondiaphragmed fenestrae of GEnC.…”

Section: Discussionmentioning

confidence: 99%

“…3 Such fenestrated endothelial cells are found in the endocrine and exocrine glands, intestinal villi, choroid plexus, liver sinusoid, kidney (both glomerular and peritubular capillaries), and so forth. 4,5 Fenestrated capillaries with diaphragmed fenestrae show a remarkably high permeability to water and other small hydrophilic solutes 6 ; however, their permeability to plasma proteins does not exceed that of the nonfenestrated capillaries or continuous capillaries. 7 The impermeability of the fenestrated capillary to plasma proteins is attributed to the existence of fenestral diaphragms and endothelial basement membrane.…”

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confidence: 99%

“…7 The impermeability of the fenestrated capillary to plasma proteins is attributed to the existence of fenestral diaphragms and endothelial basement membrane. 1,6 Each fenestral diaphragm morphologically consists of a central mesh (or knob) and several fibrils radiating from mesh to fenestral rim. 8,9 Among the several regions of endothelial cell surface, the luminal surface of fenestral diaphragm possesses the highest density of anionic sites, which is derived mainly from heparan sulfate proteoglycans.…”

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Glomerular Endothelial Cells Form Diaphragms during Development and Pathologic Conditions

Ichimura

Stan²,

Kurihara³

et al. 2008

Journal of the American Society of Nephrology

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Unlike most fenestrated capillary endothelial cells, adult glomerular endothelial cells (GEnC) are generally thought to lack diaphragms at their fenestrae, but this remains controversial. In this study, morphologic and immunocytochemical analyses demonstrated that, except for a small fraction, GEnC of adult rats lacked diaphragmed fenestrae, which contain the transmembrane glycoprotein PV-1. In contrast, the GEnC in embryonic rats exhibited diaphragmed fenestrae and expressed PV-1 protein. The luminal surface of the fenestral diaphragm possesses a high density of anionic sites, thereby compensating for the functional immaturity of the embryonic glomerular filtration barrier. In addition, GEnC with diaphragmed fenestrae and PV-1 expression were significantly increased in adult rats with Thy-1.1 nephritis, presumably reflecting a process of restorative remodeling of the glomerular capillary tuft after injury; therefore, the reappearance of PV-1 expression and diaphragmed fenestrae may serve as a marker of glomerular capillary remodeling.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Glomerular Endothelial Cells Form Diaphragms during Development and Pathologic Conditions

Ichimura

Stan²,

Kurihara³

et al. 2008

Journal of the American Society of Nephrology

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“…Water flux through the permeability barrier most likely occurs through a paracellular route. Fenestrated endothelium occurs in organs with high hydraulic conductivity, but it is conspicuously absent in tissues that limit both water and macromolecule permeability, such as the brain (29) and almost certainly facilitates the very high hydraulic conductivity of the glomerular capillary wall. However, the relative contributions of endothelial and epithelial cells in the resistance to water flow remains uncertain, but one would presume that the latter offer the greater share given the relatively smaller area of their intercellular junctions, the slit pores.…”

Section: Discussionmentioning

confidence: 99%

Glomerular permeability barrier in the rat. Functional assessment by in vitro methods.

Daniels¹,

Deen²,

Mayer³

et al. 1993

J. Clin. Invest.

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The formation of glomerular ultrafiltrate is dependent on the prevailing hemodynamic forces within the glomerular microcirculation and the intrinsic properties of the filtration barrier. However, direct assessment of the permeability barrier is difficult with most available techniques. We used confocal microscopy to image l-,m thick optical cross-sections of isolated intact glomeruli and glomeruli denuded of cells and quantitated dextran (70,000 mol wt) diffusion from the capillary lumen. Dextran permeance was 11 times greater for the acellular filtration barrier than the intact peripheral capillary. Consideration of the basement membrane and cells as series resistors demonstrated that cells of the filtration barrier contribute 90% of the total resistance to macromolecular permeance. Using a different approach, dextran sieving coefficients for acellular glomeruli consolidated as a multilayer sheet in a filtration cell were similar to those for intact glomeruli in vivo at radii 30-36 A and -50 times greater at a dextran radius of 60 A. The presence of cells significantly reduced hydraulic permeability determined on consolidated intact or acellular glomeruli in an ultrafiltration cell with 50 mmHg applied pressure. The glomerular basement membrane does restrict macromolecular permeability but cells are important determinants of the overall macromolecular and hydraulic permeability of the glomerulus. (J. Clin. Invest. 1993. 92:929-936.)

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“…Electron microscopic observations of venous capillaries in mammals reveal that these fenestrations have diameters of 50-88 nm, implying a high permeability to plasma proteins (Michel and Curry, 1999), but this is not supported experimentally. Levick and Smaje (1987) argue that other structures, such as glycoproteins and the basement membrane, contribute to the resistance of the fenestrae. These authors found that while fenestrated vessels had higher hydraulic and diffusional permeability to small hydrophilic solutes than continuous vessels, there was no change in the reflection coefficient for macromolecules such as albumin.…”

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confidence: 99%

The blood volumes of the primary and secondary circulatory system in the Atlantic codGadus morhuaL., using plasma bound Evans Blue and compartmental analysis

Skov

Steffensen

2003

Journal of Experimental Biology

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SUMMARYThe volume of the primary (PCS) and secondary (SCS) circulatory system in the Atlantic cod Gadus morhua was determined using a modified dye dilution technique. Cod (N=10) were chronically cannulated in the second afferent branchial artery with PE-50 tubing. Evans Blue dye was bound to harvested fish plasma at a concentration of 1 mg dye ml-1plasma, and injected at a concentration of 1 mg kg-1 body mass. Serial sampling from the cannula produced a dye dilution curve, which could be described by a double exponential decay equation. Curve analysis enabled the calculation of the primary circulatory and total distribution volume. The difference between these volumes is assumed to be the volume of the SCS. From the dilution curve, it was also possible to calculate flow rates between and within the systems. The results of these experiments suggest a plasma volume in the PCS of 3.42±0.89 ml 100 g-1 body mass, and in the SCS of 1.68±0.35 ml 100 g-1 body mass (mean ± S.D.) or approximately 50% that of the PCS. Flow rates to the SCS were calculated as 2.7% of the resting cardiac output. There was an allometric relationship between body mass and blood volumes. Increasing condition factor showed a tendency towards smaller blood volumes of the PCS, expressed as percentage body mass, but this was not evident for the volume of the SCS.

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An analysis of the permeability of a fenestra

Cited by 121 publications

References 39 publications

Glomerular Endothelial Cells Form Diaphragms during Development and Pathologic Conditions

Glomerular Endothelial Cells Form Diaphragms during Development and Pathologic Conditions

Glomerular permeability barrier in the rat. Functional assessment by in vitro methods.

The blood volumes of the primary and secondary circulatory system in the Atlantic codGadus morhuaL., using plasma bound Evans Blue and compartmental analysis

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