Function of the thin ascending limb of Henle of rats and hamsters perfused in vitro

1977 ◽  
Vol 232 (3) ◽  
pp. F201-F209 ◽  
Author(s):  
M. Imai
Keyword(s):  
Mammalian Species ◽  
Species Difference ◽  
Water Flux ◽  
Potential Difference ◽  
Relative Permeabilities ◽  
Bathing Medium ◽  
Solute Permeability ◽  
Osmotic Water ◽  
Net Water Flux

In order too examine whether there is species difference in the function of the thin ascending limb of Henle (tALH), segments isolated from rat and hamster kidneys were perfused in vitro and compared to results obtained by identical techniques from rabbits. The net water flux and the transtubular potential difference were not different from zero. The osmotic water permeability of the rat and hamster tALH was unmeasurably small. Isotopic and electrically determined permeabilities for Cl- and Na+ were quite high in both species, with Cl- being approximately twice as permeable as Na+. Urea permeability across the tALH of both species was moderate. Solute permeability to NaCl, urea, and raffinose (10(-5) cm sec-1) of the tALH of both species was determined by measuring changes in osmolality of the collected fluid when each solute was added to the bath at the same osmolality. They were 82.2, 38.3, and 6.9, respectively. The relative permeabilities to various ions were estimated from the deflection of the transtubular potential difference when NaCl in the bathing medium was replaced by various salts. The following sequence of permeabilities was obtained across the tALH from both the rat and hamster: Cl- greater than or equal to Br- greater than or equal to SCN- greater than or equal to I- greater than or equal to Na+ = K+ greater than Li+ greater than choline+ greater than or equal to HCO3- greater than acetate- greater than or equal to cyclamate-. These data indicate that membrane characteristics of the tALH of rats and hamsters are similar to the previously published values of rabbits. The conclusion is drawn that the principle of the passive equilibrating model of the countercurrent multiplication system is operative in other mammalian species besides the rabbit.

Applied pressures and net water flux across in vitro frog gastric mucosa.

1978 ◽  
Vol 235 (4) ◽  
pp. E361
Author(s):  
L Villegas
Keyword(s):  
Hydrostatic Pressure ◽  
Gastric Mucosa ◽  
Acid Secretion ◽  
Pressure Difference ◽  
Water Flux ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Net Water Flux ◽  
Hydrostatic Pressure Difference

The effects of hydrostatic pressure differences up to 0.4 atm/413 cmH2O were studied on frog gastric mucosa in vitro. Net water flux, transmucosal electrical potential difference, and acid secretion were measured. A significant correlation between hydrostatistic pressure difference and net water flow (r=0.77) was obtained. The intercept of the regression line, at zero hydrostatic pressure difference, is 9.3 +/- 0.5 microliter/cm2.h, and the slope 42.9 +/- 3.2 microliter/cm2.atm.h. No significant correlation was obtained between the hydrostatic pressure difference and the transmucosal potential difference (P greater than 0.20), the acid secretion (P greater than 0.20), or the nonacidic chloride transport, measured as short-circuit current (P greater than 0.20). Hydrostatic water flux is compared to osmotically induced flux previously reported. It is proposed that the difference between hydrostatic and osmotic induced water fluxes is due to the area of cells exposed to the pressures. Only part of surface cells are directly exposed to the osmotic pressure due to the presence of restricted extracellular compartments.

Sodium chloride and water transport in the renal distal tubule of the rainbow trout

1983 ◽  
Vol 244 (3) ◽  
pp. F247-F254 ◽  
Author(s):  
H. Nishimura ◽  
M. Imai ◽  
M. Ogawa
Keyword(s):  
Water Transport ◽  
Water Flux ◽  
Distal Tubule ◽  
Salmo Gairdneri ◽  
Renal Tubules ◽  
Diluting Segment ◽  
Bathing Medium ◽  
Transepithelial Voltage ◽  
Net Water Flux

Isolated segments of the renal tubules from the freshwater trout, Salmo gairdneri, were perfused in vitro to characterize ion and water transport. The distal tubule showed a transepithelial voltage (Vt) positive in the lumen (+17.8 +/- 1.4 mV). Furosemide added to the lumen and Na cyanide and ouabain added to the bath reduced the lumen-positive Vt of the distal tubule. Removal of either Cl- or Na+ from both perfusate and bathing medium abolished the lumen-positive Vt. When the distal tubule was perfused and bathed with isosmotic solution, net water flux (Jv) was nearly zero. Jv and hydraulic conductivity remained low when the osmolality of the bathing fluid was increased with raffinose. Neurohypophysial hormones added to the bath showed no effect. Chloride efflux (lumen to bath, 171.1 +/- 17.1 peq x mm-1. min-1) was significantly higher than chloride influx (bath to lumen, 105.6 +/- 12.3 peq x mm-1 x min-1), suggesting that net chloride reabsorption exists. These results suggest that in the freshwater trout, which lack the loop of Henle, the distal tubule acts as a diluting segment. The presence of sodium, in addition to chloride, is required to generate the lumen-positive Vt in the distal tubule.

Water and solute permeability of rat lung caveolae: high permeabilities explained by acyl chain unsaturation

2005 ◽  
Vol 289 (1) ◽  
pp. C33-C41 ◽  
Author(s):  
Warren G. Hill ◽  
Eyad Almasri ◽  
W. Giovanni Ruiz ◽  
Gerard Apodaca ◽  
Mark L. Zeidel
Keyword(s):  
Water Permeability ◽  
Acyl Chain ◽  
Water Flux ◽  
High Water ◽  
Fatty Acyl ◽  
Rat Lung ◽  
Membrane Structures ◽  
Solute Permeability ◽  
Outer Leaflet ◽  
Osmotic Water

Caveolae are invaginated membrane structures with high levels of cholesterol, sphingomyelin, and caveolin protein that are predicted to exist as liquid-ordered domains with low water permeability. We isolated a caveolae-enriched membrane fraction without detergents from rat lung and characterized its permeability properties to nonelectrolytes and protons. Membrane permeability to water was 2.85 ± 0.41 × 10−3 cm/s, a value 5–10 times higher than expected based on comparisons with other cholesterol and sphingolipid-enriched membranes. Permeabilities to urea, ammonia, and protons were measured and found to be moderately high for urea and ammonia at 8.85 ± 2.40 × 10−7and 6.84 ± 1.03 × 10−2 respectively and high for protons at 8.84 ± 3.06 × 10−2 cm/s. To examine whether caveolin or other integral membrane proteins were responsible for high permeabilities, liposomes designed to mimic the lipids of the inner and outer leaflets of the caveolar membrane were made. Osmotic water permeability to both liposome compositions were determined and a combined inner/outer leaflet water permeability was calculated and found to be close to that of native caveolae at 1.58 ± 1.1 × 10−3 cm/s. In caveolae, activation energy for water flux was high (19.4 kcal/mol) and water permeability was not inhibited by HgCl2; however, aquaporin 1 was detectable by immunoblotting. Immunostaining of rat lung with AQP1 and caveolin antisera revealed very low levels of colocalization. We conclude that aquaporin water channels do not contribute significantly to the observed water flux and that caveolae have relatively high water and solute permeabilities due to the high degree of unsaturation in their fatty acyl chains.

Effect of potassium on proximal tubular function

1978 ◽  
Vol 234 (5) ◽  
pp. F381-F385 ◽  
Author(s):  
J. Cardinal ◽  
D. Duchesneau
Keyword(s):  
Renal Tubule ◽  
Potential Difference ◽  
Tubular Function ◽  
Fluid Absorption ◽  
Bathing Medium ◽  
Sodium Potassium ◽  
Proximal Tubular ◽  
Proximal Tubular Function ◽  
Convoluted Tubules

In order to study the effect of potassium on the renal tubule, proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro. Omitting potassium from both the perfusate and bath caused the rate of fluid absorption and the transtubular potential difference to fall to zero. This effect was due to the absence of potassium in the bathing medium since no change was observed when potassium was omitted from the perfusate only. With 0.5 and 1.0 meq/liter of potassium in the bath, there was still a significant decrease from control in both the potential difference and the rate of fluid absorption. With 2.5 meq/liter of potassium in the bath, the results did not differ from control. In further studies, tubules were perfused with 10 meq/liter of potassium in both perfusate and bath. There was no change in the potential difference of fluid absorption. These results are consistent with the view that active transtubular transport of sodium is linked to the influx of potassium into the cell at the peritubular membrane and that this is probably mediated by sodium-potassium-ATPase. Our results also suggest that the variations of potassium concentration in the physiological range do not affect proximal tubular function.

A new technique for measuring water transport across the seawater eel intestine

1986 ◽  
Vol 122 (1) ◽  
pp. 257-268 ◽  
Author(s):  
M. Ando ◽  
H. Sasaki ◽  
K. C. Huang
Keyword(s):  
Water Flux ◽  
Experimental System ◽  
New Technique ◽  
Perfusion Method ◽  
Marker Substances ◽  
Perfusate Flow ◽  
The Difference ◽  
A New Technique ◽  
Net Water Flux

A new technique was developed for measuring net water flux across the eel intestine in vitro. The new perfusion method was suitable for long duration experiments because of continuous oxygen supply to both the external and the perfusion medium. Net water flux was calculated directly from the difference between the rates of effluent and perfusate flow without measuring the concentration of marker substances. The calculated value of net flux appears to be reliable because: its direction is always from mucosa to serosa in both everted and non-everted intestine; ouabain diminishes it to zero; it is identical with the standard water flux obtained under zero perfusion; and it is identical with the value obtained by means of [14C]PEG following the previous perfusion method. The net water fluxes obtained by the new method were steadier than those obtained with the previous complicated perfusion method. In this new experimental system, the net water flux and the transepithelial potential difference (PD) decreased gradually with time, and were not restored by application of adrenergic agonists or cortisol. These parameters were stimulated by 5 mmol l-1 L-alanine, but not by D-glucose, L-valine or L-glycine, indicating a specific action of L-alanine.

Asymmetry in osmotic response of frog gastric mucosa

1980 ◽  
Vol 238 (4) ◽  
pp. G298-G302
Author(s):  
L. Villegas
Keyword(s):  
Gastric Mucosa ◽  
Water Flux ◽  
Mucosal Surface ◽  
Ion Fluxes ◽  
Water Fluxes ◽  
Serosal Surface ◽  
Opposite Surface ◽  
Osmotic Water ◽  
Osmotic Response ◽  
Net Water Flux

The effects of hyperosmolality of the serosal and mucosal bathing solutions on the transmucosal net water and ion fluxes were studied in frog gastric mucosa. Addition of 100 mosM glucose to the solution at the serosal surface produces a reversed mucosal-to-serosal net water flux of 7.1 +/- 1.4 microliter . cm-2 . h-1. When added to the abolished spontaneous net water flux, this results in an increment in the net water flux of -17.8 +/- 1.4 microliter . cm-2 . h-1. Addition of the same amount of glucose to the solution at the mucosal surface produces an increment in the serosal-to-mucosal net water flux of 3.7 +/- 1.1 microliter . cm-2 . h-1 when the solution at the opposite surface was kept in 220 mosmol/kg H2O. Simultaneous increments of both solutions of 320 to 420 and 420 to 520 mosM changes the osmotic serosal-to-mucosal induced fluxes to 1.9 +/- 0.9 and 3.4 +/- 1.6 microliter . cm-2 . h-1, respectively. The initial spontaneous net water fluxes measured in 220, 320, and 420 mosM solutions were 11.3 +/- 0.9, 6.9 +/- 1.6, and -1.5 +/- 1.5 microliter . cm-2 . h-1. It is proposed that the osmotic water flux is asymmetric, independent of the solutions tonicities, and not significantly affected by the sweep of solutes at the mucosal surface.

Transepithelial electrical potential of nonsensory region of gerbil utricle in vitro

1986 ◽  
Vol 251 (5) ◽  
pp. C662-C670 ◽  
Author(s):  
D. C. Marcus
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Disulfonic Acid ◽  
Sensory Cells ◽  
Bathing Solution ◽  
Electrical Potential Difference ◽  
Bathing Medium ◽  
Direct Demonstration ◽  
Voltage Change

Transepithelial electrical potential difference (VT) was measured across the vestibular labyrinth of the inner ear in vitro by puncturing the epithelial wall of the utricle with a glass microelectrode. A region of nonsensory cells of the utricle was isolated from the sensory regions by introducing columns of liquid Sylgard 184. Under control conditions, the VT of this region was +7.5 +/- 0.3 mV (means +/- SE), lumen positive. This potential difference was rapidly reduced by either 1 mM ouabain, 10-100 microM bumetanide, 0.5-5.0 mM Ba (in the bathing solution), or cooling, but not by the disulfonic stilbene, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid. Changes in VT due to reductions of Cl or Na or to increases of K in the bathing solution in exchange for presumably impermeant ions were observed in this region and were compared with those in a preparation in which the insulating seals were absent. The K-induced voltage change was significantly higher in the unblocked preparation, a finding consistent with a high K permeability of the sensory cells. The voltage change due to reduction of Cl was not inhibited by Cl channel blockers (9-anthracenecarboxylate and diphenylamine-2-carboxylate) in the bathing solution. These results represent the first direct demonstration that the nonsensory cells of the utricle produce a lumen-positive active-transport potential and characterize some of the properties of the cell membranes in terms of their pharmacological sensitivities and net voltage responses to changes in the bathing medium ions Na, K, and Cl.

In Vitro Methods for the Assessment of L-Cysteine Conjugate Toxicity

1994 ◽  
Vol 22 (2) ◽  
pp. 72-80
Author(s):  
Lorraine D. Buckberry ◽  
Harriet J. Adcock ◽  
Jeremy Adler ◽  
Ian S. Blagbrough ◽  
Peter J. Gaskin ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Mammalian Species ◽  
Mercapturic Acid ◽  
Assay Method ◽  
Cellular Toxicity ◽  
In Vitro Methods ◽  
Metabolic Route ◽  
Assay Methods ◽  
Chang Liver

L-Cysteine conjugates are normally metabolised via N-acetylation to produce a mercapturic acid. However, a recently identified metabolic route (C-S lysis) may lead to the generation of an unstable thiol which has been demonstrated to be responsible for toxicity in various mammalian species. Human Chang liver cells were challenged with a number of established L-cysteine conjugates. The cellular toxicity of these compounds was determined using a range of assay procedures, which provided differing information, depending on the assay method used. These observations were then investigated in order to establish which system would provide the most reliable indication of C-S lyase toxicity and whether any information on the mechanism of action could be obtained by these assay methods.

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