Extravascular renal albumin

Slotkoff, LM; Lilienfield, LS

doi:10.1152/ajplegacy.1967.212.2.400

Cited by 29 publications

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“…Similar experiments were also performed in which 5'Cr-labeled red blood cells and iodinated albumin were injected and the renal vasculature flushed or ligated ( 1,2). Those investigations suggested the existence ofa large extravascular pool ofalbumin in the renal medulla.…”

Section: Introductionmentioning

confidence: 84%

Molecular sieving of albumin by the ascending vasa recta wall.

Pallone

1992

J. Clin. Invest.

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Molecular sieving of albumin by ascending vasa recta. Evidence exists to support the presence of an extravascular pool of albumin in the renal medullary interstitium. This study used microperfusion in vivo to measure the transport of '25I-labeled albumin from descending (DVR) and ascending vasa recta (AVR) to the papillary interstitium. Perfusions were performed during furosemide diuresis with a buffer containing FITC-labeled dextran (FITC-Dx) 2 X 106 mol wt and 125I-albumin. Perfusate albumin and collection pressure were adjusted to induce either zero transcapillary volume flux (Jv) or high volume flux. When Jv was zero, the collectate-to-perfusate ratios of FITC-Dx (RDX) and 125I-albumin (Rkb) in the DVR and AVR were identical implying that diffusive efflux of albumin was immeasurably small. In contrast, when Jv was increased, paired comparison of R.Jb and RDX in the same AVR revealed a difference, 1.58±0.06 vs 1.72±0.08, respectively (P < 0.01). AVR perfusions in hydropenic animals showed similar results, R.Jb = 1.70±0.07 and RDX = 2.00±0.07 (P < 0.01).These data suggest that albumin transport across vasa recta in vivo is likely to be governed by solvent drag. The reflection coefficient of the AVR wall to 125I-albumin is estimated to be 0.78. (J. Clin. Invest. 1992. 90:30-34.) Key words:

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Section: Introductionmentioning

confidence: 84%

Molecular sieving of albumin by the ascending vasa recta wall.

Pallone

1992

J. Clin. Invest.

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“…The most likely possibility is that the use of the albumin label as a measure of plasma volume is a source of error, and that it measures substantially more than the plasma volume of the renal circulation. Criticism against the method has been leveled by several workers in the field (15)(16)(17)(18)(19)(20). Baker lr The drainage volume in 8 experiments (9) was 19.2 ml, with hematocrit 0.87% of vein blood; residual volume was 6.7 ml (hematocrit 0.18 of venous blood).…”

Section: Selkurt Laurencementioning

confidence: 99%

“…First, the albumin molecule will leak out of the capillaries into the interstitial space where it will accumulate and ultimately enter the lymphatic channels of the kidney (16)(17)(18)(19)(20)(21). Second, labeled albumin would filter through the glomerular membranes of the kidney to a limited extent and accumulate in the fluid of the nephrons and in tubular cells, thus adding a portion of the tubular fluid volume to the calculated intra vascular volume (22)(23)(24)(25).…”

Section: Selkurt Laurencementioning

confidence: 99%

“…Third, there is ample evidence that albumin is concentrated in the medulla of the kidney by the countercurrent exchange mechanism, possibly by short circuiting of water across the loop of Henle (26)(27)(28). To the extent that albumin accumulates here it will yield erroneously high values for the calculation of the intravascular plasma volume, thus adding to the total error involved in the measurement of the apparent renal plasma volume (16,18,19,20,29). It is noteworthy that red cell volume per gram of tissue is very similar in the inner medulla and the cortex (5, 30) so that the low apparent hematocrit in the medulla could be the result of the large "apparent" albumin space.…”

Section: Selkurt Laurencementioning

confidence: 99%

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Examination of the Intrarenal Hematocrit Ratio with the Technique of Circulatory Stop-Flow in Dogs

Selkurt

Laurence

1969

Circulation Research

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Estimates of the intrarenal hematocrit ratio vary widely, depending on the techniques used for its determination. Computation of blood volume from the product of mean transit time of labeled erythrocytes and albumin, and minute volume blood flow, yields values averaging approximately 90% of the systemic vessel hematocrit. To the other extreme are values that are slightly less than half of the systemic hematocrit ratio based on the determination of total renal blood volume by labeled red cells and albumin. Intermediate values are obtained by methods involving draining the blood from the kidney and measuring its hematocrit ratio. The current investigation, by a technique of circulatory stop-flow, has shown that a substantial fluid shift occurs in the kidney within 2 minutes of circulatory arrest, so that interstitial fluid, supplemented by fluid reabsorbed by the nephrons, dilutes the erythrocytes within the peritubular capillaries to reduce the hematocrit ratio to almost half of the systemic figure. The drainage methods are subject to error as a result of this mechanism, but if such fluid shifts are taken into account, values for the intrarenal hematocrit closer to the ratio of systemic blood can be anticipated.

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“…They found a rapid loss of protein from post-glomerular vessels; 50 per cent of extravascular protein exchanged in 12 minutes -a very rapid rate of exchange compared to that of other organs. Pinter [1967], using isotope-labelled chylomicrons as an indicator of intravascular plasma space, found a large quantity of extravascular albumen in the kidney, equivalent to 31 per cent of the total renal albumen.A more direct method was that of Slotkoff and Lilienfield [1967] who injected 131I albumen and 51Cr red cells into dogs and then perfused the vascular system with dextran to clear the vessels of blood. They found a significantly higher proportion of albumen than of red cells remaining in the kidney, presumably indicating an extravascular albumen pool.…”

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confidence: 99%

Extravascular Protein in the Renal Medulla

Moffat¹

1969

Exp Physiol

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The permeability to protein of the vessels of the renal medulla in the rat was studied by intravenous injection of Evans' Blue or fluorescent-labelled serum, followed by perfusion of the whole vascular system with saline. The vessels of the inner medulla and the vasa recta of the vascular bundles of the outer medulla were found to be rapidly and freely permeable to protein. Electron microscopy, after the injection of ferritin, Thorotrast or colloidal gold, showed the vessels probably concerned in the protein leak to be ascending vasa recta and the capillaries of the medulla. The findings support suggestions that extravascular albumen is important in the process of concentration of the urine.THERE is considerable evidence for the existence of a large pool of exchangeable albumen in the kidney, and the results of a number of studies suggest that much of this is extravascular. This has been shown by the many workers who have used radioactive albumen and labelled red cells to investigate the relative distribution of cells and plasma in the kidney Collings and Swann, 1958;Lassen et al., 1958;Goldberg and Lilienfield, 1963;Ochwadt, 1963;Chinard et al., 1964]. More recently, Giirtner et al. [1968] have investigated the problem using 1311 albumen and polyvinylpyrrolidon to follow the fate of large molecules. They found a rapid loss of protein from post-glomerular vessels; 50 per cent of extravascular protein exchanged in 12 minutes -a very rapid rate of exchange compared to that of other organs. Pinter [1967], using isotope-labelled chylomicrons as an indicator of intravascular plasma space, found a large quantity of extravascular albumen in the kidney, equivalent to 31 per cent of the total renal albumen.A more direct method was that of Slotkoff and Lilienfield [1967] who injected 131I albumen and 51Cr red cells into dogs and then perfused the vascular system with dextran to clear the vessels of blood. They found a significantly higher proportion of albumen than of red cells remaining in the kidney, presumably indicating an extravascular albumen pool.Attempts to visualize the extravascular albumen directly have met with conflicting results. Pomerantz et al. [1965], using fluorescin-labelled albumen in rats, found that fluorescence microscopy showed extravascular protein, particularly in the medulla, as little as 40 seconds after the injection. Carone et al. [1963, 1967], on the other hand, found albumen only within the vessels. Wilde and Vorburger [1967], who used Evans' Blue in hamsters, described and illustrated extravascular dye in freeze-dried kidneys embedded in Epon. A number of other authors who have used Evans' Blue to study the renal circulation have noticed staining of the kidneys as an incidental 60

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Extravascular renal albumin

Cited by 29 publications

References 0 publications

Molecular sieving of albumin by the ascending vasa recta wall.

Molecular sieving of albumin by the ascending vasa recta wall.

Examination of the Intrarenal Hematocrit Ratio with the Technique of Circulatory Stop-Flow in Dogs

Extravascular Protein in the Renal Medulla

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