Non-Electrolyte Permeability Across thin Lipid Membranes

Gallucci, E.; Micelli, S.; Lippe, C

doi:10.3109/13813457109104847

Cited by 86 publications

(50 citation statements)

References 22 publications

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“…However, in vitro studies revealed that urea permeability across artificial lipid bilayers was considerably lower than previously thought (34,35). This is particularly true for cartilaginous fishes.…”

Section: Urea Retention In the Kidney: Urea Transportermentioning

confidence: 77%

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Hyodo

Kakumura

Takagi

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption. Am J Physiol Regul Integr Comp Physiol 307: R1381-R1395, 2014. First published October 22, 2014 doi:10.1152/ajpregu.00033.2014.-For adaptation to highsalinity marine environments, cartilaginous fishes (sharks, skates, rays, and chimaeras) adopt a unique urea-based osmoregulation strategy. Their kidneys reabsorb nearly all filtered urea from the primary urine, and this is an essential component of urea retention in their body fluid. Anatomical investigations have revealed the extraordinarily elaborate nephron system in the kidney of cartilaginous fishes, e.g., the four-loop configuration of each nephron, the occurrence of distinct sinus and bundle zones, and the sac-like peritubular sheath in the bundle zone, in which the nephron segments are arranged in a countercurrent fashion. These anatomical and morphological characteristics have been considered to be important for urea reabsorption; however, a mechanism for urea reabsorption is still largely unknown. This review focuses on recent progress in the identification and mapping of various pumps, channels, and transporters on the nephron segments in the kidney of cartilaginous fishes. The molecules include urea transporters, Na, and aquaporins, which most probably all contribute to the urea reabsorption process. Although research is still in progress, a possible model for urea reabsorption in the kidney of cartilaginous fishes is discussed based on the anatomical features of nephron segments and vascular systems and on the results of molecular mapping. The molecular anatomical approach thus provides a powerful tool for understanding the physiological processes that take place in the highly elaborate kidney of cartilaginous fishes. cartilaginous fish; kidney; osmoregulation; transporters; urea BODY FLUID REGULATION is essential for all organisms to survive in their respective habitats, including freshwater (FW), seawater (SW), and terrestrial environments. It is well known that teleost fish regulate their plasma Na ϩ and Cl Ϫ concentrations and osmolality at levels about one-third of SW. Meanwhile, cartilaginous fishes (sharks, skates, rays, and chimaeras) have adopted a unique osmoregulatory strategy for adaptation to the high-salinity marine environment. Cartilaginous fishes control plasma ions to levels approximately one-half of surrounding SW while they store high concentrations of the nitrogenous compound urea as an osmolyte (the so-called "ureosmotic strategy"). As a result, their body fluids are slightly hyperosmotic to surrounding SW (for instance, plasma osmolality of houndshark is 1,000 mosmol/kg H 2 O in SW of 988 mosmol/kg H 2 O; Ref. 53), and thus cartilaginous fishes do not typically suffer dehydration even in the high-osmolality SW environment. To maintain high concentration of urea in the body, urea production by the ornithine urea cycle (OUC) is essential. Investigations on the OUC enzymes have proved that the liver is the primary organ f...

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Section: Urea Retention In the Kidney: Urea Transportermentioning

confidence: 77%

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Hyodo

Kakumura

Takagi

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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“…2b), as shown previously [18]. The urea permeability of artificial bilayer membranes is relatively low [19]; however, it has been known for some time that urea transport in human red blood cells occurs largely by facilitated diffusion [17], which may also be present in the alveolar and airway epithelium [17]. Owing to this fast diffusion across cell membranes, unlike chelates such as DTPA, urea may not be considered an appropriate extracellular indicator.…”

Section: Discussionmentioning

confidence: 93%

Comparison of^99mTc‐DTPA and urea for measuring cefepime concentrations in epithelial lining fluid

Bayat¹,

Louchahi²,

Verdière³

et al. 2004

Eur Respir J

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The efficacy of antimicrobial agents against pulmonary infections depends on their local concentrations in the lung. The aims of the present study were to: 1) compare technetium-99m diethylenetriaminepenta-acetic acid ( 99m Tc-DTPA) and urea as markers of epithelial lining fluid (ELF) dilution for measuring ELF concentrations of pharmaceuticals; 2) quantify ELF cefepime concentrations in normal and injured lung; and 3) measure the increase in permeability to cefepime following oleic acid-induced acute lung injury.A modified bronchoalveolar lavage technique, based on equilibration of infused 99mTc-DTPA, was used to measure ELF volume. Cefepime was administered intravenously at steady plasma levels. Six serial bronchoalveolar lavages were performed 5 h after the beginning of infusion.ELF to plasma cefepime concentration ratios were 95¡17 and 100¡14.5% in normal and injured lung respectively. When urea was used as marker, cefepime concentration ratios were underestimated at 16.4¡2.7 and 73.9¡8.4% respectively. Cefepime blood/ airspace clearance increased from 3.8¡0.7 mL?min -1 in controls to 39.8¡4.9 mL?min -1 in acute lung injury. It was concluded that: 1) cefepime concentrations in epithelial lining fluid were in equilibrium with those in plasma in both normal and injured lung after 5 h at steady plasma concentrations; 2) epithelial lining fluid cefepime concentration by the urea method was much less underestimated in injured versus normal lung; and 3) acute lung injury induces a 10-fold elevation of cefepime blood/airspace clearance. Eur Respir J 2004; 24: 150-156.

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“…The conclusion from the comparative results of urea and water transport (see below) is also that this abundant transporter per se does not create a leak pathway to urea and water. cms -1 at 20-28°C in different lipid bilayer membrane systems with no built-in transporters (Vreeman, 1966;Galucci et al, 1971;Poznansky et al, 1976). Thiourea is ~10× more lipid soluble than urea (Collander and Bärlund, 1933), and the similar P urea and P thiourea in artificial bilayer membrane systems underline the fact that factors other than the partition coefficient, such as the entrance and exit rates of the solute in the membrane, are important.…”

Section: The Journal Of Experimental Biology 216 (12)mentioning

confidence: 99%

The permeability of red blood cells to chloride, urea, and water

Brahm

2013

Journal of Experimental Biology

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SUMMARYThis study extends permeability (P) data on chloride, urea and water in red blood cells (RBC), and concludes that the urea transporter (UT-B) does not transport water. cms -1 (human). DIDS, DNDS and phloretin inhibit P Cl by >99% in all RBC species. PCMBS, PCMB and phloretin inhibit P urea by >99% in Amphiuma, dog and human RBC, but not in chick and duck RBC. PCMBS and PCMB inhibit P d in duck, dog and human RBC, but not in chick and Amphiuma RBC. Temperature dependence, as measured by apparent activation energy, E A , of P Cl is 117.8 (duck), 74.9 (Amphiuma) and 89.6kJmol −1 (dog). The E A of P urea is 69.6 (duck) and 53.3kJmol −1 (Amphiuma), and that of P d is 34.9 (duck) and 32.1kJmol −1 (Amphiuma). The present and previous RBC studies indicate that anion (AE1), urea (UT-B) and water (AQP1) transporters only transport chloride (all species), water (duck, dog, human) and urea (Amphiuma, dog, human), respectively. Water does not share UT-B with urea, and the solute transport is not coupled under physiological conditions.

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Non-Electrolyte Permeability Across thin Lipid Membranes

Cited by 86 publications

References 22 publications

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Comparison of^99mTc‐DTPA and urea for measuring cefepime concentrations in epithelial lining fluid

The permeability of red blood cells to chloride, urea, and water

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Non-Electrolyte Permeability Across thin Lipid Membranes

Cited by 86 publications

References 22 publications

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

Comparison of99mTc‐DTPA and urea for measuring cefepime concentrations in epithelial lining fluid

The permeability of red blood cells to chloride, urea, and water

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Comparison of^99mTc‐DTPA and urea for measuring cefepime concentrations in epithelial lining fluid