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  • 1
    Online Resource
    Online Resource
    American Physiological Society ; 2001
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 281, No. 4 ( 2001-10-01), p. H1728-H1733
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 281, No. 4 ( 2001-10-01), p. H1728-H1733
    Abstract: N-ethylmaleimide (NEM) has been claimed to markedly inhibit the transvascular passage of small proteins and albumin by interacting with the docking and fusion of plasmalemmal vesicles with their target membranes. To investigate the role of transcytosis in the transcapillary passage of albumin, we assessed the effects of NEM on 125 I-labeled radioiodinated serum albumin clearance (RISA-Cl) from blood to muscle in isolated and maximally vasodilated perfused rat hindquarters, in which vascular pressures, pre- and postcapillary resistances, and the capillary filtration coefficient (CFC) were continuously monitored. NEM (0.3–0.5 mM) caused a marked increase mainly in precapillary vascular resistance. Thus the arterial-to-venous resistance ratio in NEM-treated animals was 3.12 ± 0.56 versus 1.66 ± 0.17 during the control period ( P 〈 0.05). Despite that, there was a doubling of both CFC from 0.0363 ± 0.0028 to 0.0778 ± 0.0101 ml · min −1 · mmHg −1 · 100 g −1 ( P 〈 0.01) and RISA-Cl, compared with the control situation, signaling markedly increased microvascular permeability. Our results strongly suggest that NEM, besides producing marked vasoconstriction, also causes damage to the capillary endothelium. Thus, instead of inhibiting transvascular transport, NEM may induce increases in the bulk transport of albumin from blood to tissue.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2001
    detail.hit.zdb_id: 1477308-9
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  • 2
    In: Blood Purification, S. Karger AG, Vol. 16, No. 3 ( 1998), p. 162-170
    Abstract: Mass transfer area coefficients (PS) to small solutes are usually markedly increased during the first 0–15 min of peritoneal dialysis (PD) dwells. This phenomenon may be due to, for example, initial arteriolar vasodilatation and, hence, recruitment of capillary surface area. Other possibilities are an initial discharge (or saturation) of solutes from (in) the interstitium or an increased mixing, i.e., ‘macrostirring’ caused by the exchange procedure per se. We have investigated these possibilities during acute PD in rats, by assessing PS for 〈 sup 〉 51 〈 /sup 〉 Cr-EDTA as a function of time [PS(t)]. The discharge effect was studied by saturating the peritoneal interstitium with 〈 sup 〉 51 〈 /sup 〉 Cr-EDTA by intravenous tracer infusion prior to each dwell and the results compared to those obtained in rats when tracer infusion and dwells were started simultaneously. The potential effect of initial vasodilatation was studied by adding isoproterenol to the dialysis fluid. Finally, the potential influence of an increased interstitial ‘microstirring’, induced by high glucose concentrations, was investigated by comparison of results for 1.36% Dianeal 〈 sup 〉 ® 〈 /sup 〉 with those for 3.86% Dianeal. In nonvasodilated rats there was a significant drop in PS(t) between 2.5 and 15 min regardless of whether the rats were preloaded with tracer or not. However, there were no significant changes in PS(t) within the isoproterenol-treated group, indicating that vasodilatation plays a crucial role for the high PS initially. Furthermore, there was no difference in overall PS for 〈 sup 〉 51 〈 /sup 〉 Cr-EDTA among 1.36 and 3.86% Dianeal dwells. In conclusion, we have found that vasodilatation, but not interstitial discharge (or loading), may explain the inflation of PS occurring during the initial part of PD dwells. In addition, ‘macrostirring’, induced by the exchange procedure per se, may also be important.
    Type of Medium: Online Resource
    ISSN: 0253-5068 , 1421-9735
    Language: English
    Publisher: S. Karger AG
    Publication Date: 1998
    detail.hit.zdb_id: 1482025-0
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  • 3
    In: Journal of Vascular Research, S. Karger AG, Vol. 41, No. 2 ( 2004), p. 123-130
    Abstract: During the last decades there has been a debate regarding whether transvascular protein transport is an active (transcytosis) or a passive (porous) process. To separate cooling-sensitive transcytosis from passive transport processes between blood and peritoneal fluid, we induced hypothermia in rats in vivo, reducing their body temperature to 19°C. Control rats were kept at 37°C. Either human albumin, or IgG, or IgM, or LDL, radiolabeled with 〈 sup 〉 125 〈 /sup 〉 I, was given intra-arterially together with 〈 sup 〉 51 〈 /sup 〉 Cr-EDTA. During tracer administration, a 2-hour peritoneal dialysis dwell was performed. Clearance of the tracers to dialysate, and the permeability-surface area coefficient (PS) for 〈 sup 〉 51 〈 /sup 〉 Cr-EDTA and glucose were assessed. During cooling, mean arterial blood pressure (MAP) was reduced to 40% of control and plasma viscosity increased by 48.5%, while peritoneal blood flow was reduced to 10%. At 19°C, clearance of albumin to dialysate fell from 9.30 ± 1.62 (SEM) to 3.13 ± 0.28 µl/min (p 〈 0.05), clearance of IgG from 6.33 ± 0.42 to 2.54 ± 0.12 µl/min (p 〈 0.05), clearance of IgM from 3.65 ± 0.33 to 1.10 ± 0.12 µl/min (p 〈 0.05), and clearance of LDL from 3.54 ± 0.20 to 0.73 ± 0.06 µl/min (p 〈 0.05). The fall in PS for 〈 sup 〉 51 〈 /sup 〉 Cr-EDTA was from 0.320 ± 0.01 to 0.075 ± 0.003 ml/min (p 〈 0.05), and that for glucose from 0.438 ± 0.02 to 0.105 ± 0.01 ml/min (p 〈 0.05). Tissue cooling reduced large solute transport largely in proportion to the cooling-induced reductions of MAP (to 40%), and the concomitant increase in viscosity (to 67%), i.e. to & #8776;20–30% (0.40 × 0.67) of control, though LDL clearance was reduced further. The fall in small solute PS, in excess of the viscosity effect, mirrored the fall in peritoneal blood flow occurring during hypothermia. In conclusion, the good correlation of predicted to calculated changes suggests that the overall transendothelial macromolecular passage in vivo occurs passively, and not due to active processes.
    Type of Medium: Online Resource
    ISSN: 1018-1172 , 1423-0135
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2004
    detail.hit.zdb_id: 1482726-8
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  • 4
    Online Resource
    Online Resource
    SAGE Publications ; 1999
    In:  Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis Vol. 19, No. 2_suppl ( 1999-02), p. 95-101
    In: Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis, SAGE Publications, Vol. 19, No. 2_suppl ( 1999-02), p. 95-101
    Type of Medium: Online Resource
    ISSN: 0896-8608 , 1718-4304
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1999
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  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 2006
    In:  Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis Vol. 26, No. 3 ( 2006-05), p. 353-359
    In: Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis, SAGE Publications, Vol. 26, No. 3 ( 2006-05), p. 353-359
    Abstract: In computer simulations, according to the three-pore model of peritoneal transport, neutralization of conventional acidic peritoneal dialysis fluids is predicted to produce an improved ultrafiltration (UF). However, in a previous study, a two-compartment peritoneal dialysis system with a minimum of glucose degradation products (GDP), PD-Bio, having a pH of 6.3 and being conventionally lactate buffered, did not produce an increased UF. Setting We tested a newly formulated, glucose-based, GDP-reduced solution, denoted “N” for “neutral,” containing a mixture of lactate (30 mmol/L) and bicarbonate (10 mmol/L) as buffer system, and having a pH of 7.2. This new formulation was compared with Gambrosol trio (GT) (identical in composition to PD-Bio, but delivered in a three-compartment system; both by Gambro Lundia AB, Lund, Sweden) in an open, prospective controlled study of 13 patients. Material and Methods Each of the 13 patients used GT for 14 days, followed by 14 days of N. All bags were weighed on a digital scale before instillation and after drainage to assess the UF in each dwell (and during 24 hours). Glucose concentration in each bag was noted. In the morning and night dwells, dialysis fluid glucose concentration was standardized to 2.5%. Body weight was measured every morning (empty abdomen). In the middle of each 14-day period, a 4-hour standardized (“study day”) dwell was performed, using 125 I-albumin (RISA) as volume marker, during which blood and dialysate samples were taken repeatedly and analyzed for RISA, creatinine, urea, phosphate, glucose, standard bicarbonate, lactate, and pH. The permeability surface area product (PS) for small solutes (and A 0 /ΔX; “area parameter”) was calculated. Clearance (Cl) of RISA to plasma (P) (Cl→P), “direct lymphatic absorption,” and total Cl of RISA out of the peritoneal cavity (Cl out ) were also determined. Results The 13 patients using N, compared to GT, displayed an increased daily UF, the difference being 233 mL ( p 〈 0.05). The pH values of N were higher during the first 90 minutes of the 4-hour dwell compared to the pH values of GT. Neither the small solute PS values nor RISA determined UF, nor did body weight differ significantly between the GT and the N periods. Conclusions A new bicarbonate/lactate-buffered solution, N, with neutral pH (of 7.2) and low in GDP seems to produce an improved UF compared to a lactate-buffered solution with a pH of 6.3, equally low in GDP, partly in agreement with our earlier predictions. A dialysis solution with a neutral pH combined with a reduced lactate concentration, partially replaced by bicarbonate, evidently increases UF, conceivably by causing less peritoneal vasodilatation than solutions buffered by lactate or high concentrations of bicarbonate alone.
    Type of Medium: Online Resource
    ISSN: 0896-8608 , 1718-4304
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
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  • 6
    Online Resource
    Online Resource
    SAGE Publications ; 1998
    In:  Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis Vol. 18, No. 5 ( 1998-09), p. 497-504
    In: Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis, SAGE Publications, Vol. 18, No. 5 ( 1998-09), p. 497-504
    Abstract: To assess the clearance of radiolabeled tracer albumin (RISA) from peritoneal cavity to plasma (CI → P) in rats under essentially “normal” conditions, that is, when intraperitoneal hydrostatic pressure (IPP) is subatmospheric and the intraperitoneal (IP) “free” fluid volume (IPV) is low. Methods A volume of 0.3 mL of RISA was injected IP into anesthetized Wistar rats (wt = 300 g) when the IPV was approximately 2 mL (normal) or the IPV was approximately 10 mL, and IPP was either -1.8 mmHg (normal) or +1.5 mmHg (produced by an external cuff). Plasma samples (25 μL) were obtained repeatedly during the dwell, which lasted 30 300 min, after which the peritoneal cavity was opened to recover the IPV and residuallP RISA activity. The CI → P was assessed as the mass transfer of RISA into plasma, occurring per unit time,-divided by the calculated mean IP RISA concentration (CD). The interstitial RISA space was measured as the mass of RISA accumulated, per unit tissue weight, in peritoneal tissue samples divided by the CD. Results A markedly lower CI → P (2.47 ± 0.67 μL/min), as well as total RISA clearance out of the peritoneal cavity (CI), was found under “normal” conditions (an IPV of approximately 2 mL and an IPP of approximately -1.8 mmHg) compared to the situation during peritoneal dialysis (an IPV of approximately 20 mL and an IPP of +1 mmHg). Furthermore, the interstitial RISA space increased linearly over time even at negative IPPs and at an unchanging peritoneal interstitial fluid volume. At a low (normal) IPV the CI → P did not increase significantly with elevating IPP, and increased only marginally when tracer distribution was improved by artificial vibration of the rats. However the CI → P increased when larger volumes were infused to increase the totallPV. Conclusions It is concluded that the CI → P and CI at low IPPs and IPVs are not as high as during peritoneal dialysis. Increases in CI → P were, however, coupled to increases in IPV. This highlights the importance of the IPV per se and of a sufficient IP tracer distribution for direct lymphatic absorption to be efficient. This study was presented in part at the XVIth Annual Conference on Peritoneal Dialysis, Denver, Colorado, U.S.A., 1997 (33).
    Type of Medium: Online Resource
    ISSN: 0896-8608 , 1718-4304
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1998
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  • 7
    Online Resource
    Online Resource
    American Physiological Society ; 1999
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 277, No. 3 ( 1999-09-01), p. H1107-H1112
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 277, No. 3 ( 1999-09-01), p. H1107-H1112
    Abstract: Lymph flow is elevated in most inflammatory conditions. However, a few previous studies have indicated that peritoneal lymph flow may actually fall during acute peritonitis. This study was performed to explore this issue further and to study the pathophysiology of peritoneal exchange during peritonitis. Therefore, we wanted to assess the total peritoneal clearance (Cl) and the clearance from peritoneum to plasma (Cl → P) of 125 I-labeled albumin ( 125 I-albumin) as well as plasma-to-dialysate clearance (Cl → D) of Evans blue-labeled albumin together with peritoneal ultrafiltration (UF) profiles and mass transfer area coefficients of 51 Cr-EDTA and glucose in rats after acute peritonitis induced by zymosan. Zymosan incubation of the peritoneal cavity (120 mg) for 4 h generally led to a 4- to 10-fold increase in peritoneal fluid white blood cell count, indicating that acute peritonitis had been induced. Then 16 ml of 3.86% Dianeal and 125 I-albumin were instilled intraperitoneally, whereas Evans blue-labeled albumin and 51 Cr-EDTA were given as infusions intravenously. Compared with control, mass transfer area coefficients for glucose and 51 Cr-EDTA increased markedly from 0.43 ± 0.06 and 0.25 ± 0.04 to 0.91 ± 0.06 and 0.59 ± 0.05 (SE) ml/min, respectively, during peritonitis, whereas Cl and Cl → D increased from 32.8 ± 5.6 and 8.6 ± 1.6 to 74.5 ± 7.3 and 12.9 ± 1.0 μl/min, respectively. The UF profile in peritonitis indicated type I loss of UF (resulting from the increases in permeability-surface area product for glucose). However, the Cl → P declined to 5.9 ± 1.0 μl/min from 7.9 ± 0.8 μl/min ( P 〈 0.05) in control. In conclusion, despite marked effects on peritoneal solute transport and on UF, conceivably resulting from vasodilatation and increases in capillary permeability, zymosan-induced peritonitis did not cause any acute increases in direct peritoneal lymphatic absorption.
    Type of Medium: Online Resource
    ISSN: 0363-6135 , 1522-1539
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1999
    detail.hit.zdb_id: 1477308-9
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  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 1996
    In:  Kidney International Vol. 50, No. 1 ( 1996-06), p. 298-303
    In: Kidney International, Elsevier BV, Vol. 50, No. 1 ( 1996-06), p. 298-303
    Type of Medium: Online Resource
    ISSN: 0085-2538
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1996
    detail.hit.zdb_id: 2007940-0
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  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2004
    In:  Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis Vol. 24, No. 1 ( 2004-01), p. 37-47
    In: Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis, SAGE Publications, Vol. 24, No. 1 ( 2004-01), p. 37-47
    Abstract: Long-term peritoneal dialysis (PD) leads to structural and functional changes in the peritoneum. The aim of the present study was to investigate the long-term effects of PD fluid components, glucose and glucose degradation products (GDP), and lactate-buffered solution on morphology and transport characteristics in a nonuremic rat model. Methods Rats were subjected to two daily intraperitoneal injections (20 mL/day) during 12 weeks of one of the following: commercial PD fluid (Gambrosol, 4%; Gambro AB, Lund, Sweden), commercial PD fluid with low GDP levels (Gambrosol trio, 4%; Gambro AB), sterile-filtered PD fluid (4%) without GDP, or a glucose-free lactate-buffered PD fluid. Punctured and untreated controls were used. Following exposure, the rats underwent a single 4-hour PD dwell (30 mL, 4% glucose) to determine peritoneal function. Additionally, submesothelial tissue thickness, percentage of high mesothelial cells (perpendicular diameter 〉 2 μm), vascular density, vascular endothelial growth factor (VEGF), and transforming growth factor (TGF) β 1 mRNA expression were determined. Submesothelial collagen concentration was estimated by van Gieson staining. Results Submesothelial tissue thickness and vascular density, mediated by VEGF and TGFβ production, in the diaphragmatic peritoneum increased significantly in rats exposed to any PD fluid. Gambrosol induced a marked increased fibrosis of the hepatic peritoneum. A significant increase in high mesothelial cells was observed in the Gambrosol group only. Net ultrafiltration was reduced in the Gambrosol and in the glucose-free groups compared to untreated controls. Small solute transport was unchanged, but all groups exposed to fluids showed significantly increased lymph flow. Conclusions Our results show that long-term exposure to different components of PD fluids leads to mesothelial cell damage, submesothelial fibrosis, and neoangiogenesis. Mesothelial cell damage could be connected to the presence of GDP; the other changes were similar for all fluids. Peritoneal transport characteristics did not change in any consistent way and the neoangiogenesis observed was not paralleled by increased solute transport.
    Type of Medium: Online Resource
    ISSN: 0896-8608 , 1718-4304
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2004
    detail.hit.zdb_id: 2075957-5
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  • 10
    Online Resource
    Online Resource
    SAGE Publications ; 1996
    In:  Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis Vol. 16, No. 1_suppl ( 1996-01), p. 97-103
    In: Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis, SAGE Publications, Vol. 16, No. 1_suppl ( 1996-01), p. 97-103
    Abstract: In this article the difference between osmotic fluid flow (ultrafiltration) as driven by osmotic pressure and diffusion through thin leaky membranes is discussed. It is pointed out that water transport induced by osmosis is fundamentally different from the process of water diffusion. Applying modern hydrodynamic pore theory, the molar solute concentration and the solute concentration in grams per 100 mL, exerting the same initial transmembrane osmotic pressure as a 1% glucose solution, was investigated as a function of solute molecular weight (MW). It was then assumed, based on experimental data, that the major pathway responsible for the peritoneal osmotic barrier characteristics is represented by pores of radius ~47 å. With increasing solute radius, the osmotic reflection coefficient (σ) and, hence, the osmotic efficiency per mole of solute will increase. However, simultaneously, the molar concentration per unit solute weight will decrease. The balance point between these two events apparently occurs at a solute MW of approximately 1 kCa. An additional advantage of using solutes of high MW as osmotic agents during peritoneal dialysis (PC), rather than increased osmotic efficiency per se, lies in the fact that large solutes, due to their low peritoneal diffusion capacity, will maintain a sustained rate of ultrafiltration (osmosis) over a prolonged period. To illustrate this, we have performed computer simulations of peritoneal fluid transport according to the three-pore model of peritoneal permselectivity. According to these simulations, 4% of an 800 Ca polymer solution (+50 mmol/ L above isotonicity) will produce the same cumulative amount of intraperitoneal fluid volume ultrafiltered (UF) during 360 -400 minutes as 4% of a 2 kCa polymer solution (+20 mmol/L) or 6.5% of a 10 kCa polymer solution (+6.5 mmol/L) having the same electrolyte concentration as dialysis solutions conventionally used for PC. Similar cumulative UF volumes (during 400 minutes) can be obtained by a 2.5% glycerol (+272 mmol/L) or a 3.2% glucose-containing dialysis solution (+177 mmol/L) with conventional electrolyte composition.
    Type of Medium: Online Resource
    ISSN: 0896-8608 , 1718-4304
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1996
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