Simple multichannel system for the measurement of the net water flux across biological tissues

2007 ◽  
Vol 85 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Mariano E. Fernández-Miyakawa ◽  
Ricardo Dorr ◽  
Luis E. Fernández ◽  
Francisco A. Uzal ◽  
Cristina Ibarra
Keyword(s):  
Water Flux ◽  
Biological Tissues ◽  
Multichannel System ◽  
Net Water Flux

Net Fluxes of Water in the Isolated Gills of Anguilla Dieffenbachii

1974 ◽  
Vol 60 (3) ◽  
pp. 769-781
Author(s):  
T. J. SHUTTLEWORTH ◽  
R. F. H. FREEMAN
Keyword(s):  
Sea Water ◽  
Water Flux ◽  
Freshwater Teleost ◽  
Osmotic Permeability ◽  
Direct Measurements ◽  
Net Flux ◽  
Anguilla Dieffenbachii ◽  
Net Fluxes ◽  
Freshwater Eels ◽  
Net Water Flux

1. Measurements of net flux of water have been made on isolated gills removed from freshwater-adapted and seawater-adapted eels and incubated in various media of differing osmotic pressure. 2. From these measurements it has been possible to determine the osmotic permeability coefficient of the gill directly from the net water flux. The values obtained (0.50±0.14x10-5 cm.sec-1 for freshwater eels and 0.43±0.07x10-5 cm.sec-1 for seawater-adapted eels) indicate that there was no significant change in this parameter on adaptation of the eels to sea water. 3. The direct measurements made of the net water flux across the isolated gills appear to be compatible with the osmoregulatory pattern of eels as deduced by other workers using different techniques. In particular they illustrate and further emphasize the significance of drinking in the freshwater fish. 4. Calculations indicate that, for a freshwater teleost, the osmotic and ionic problems caused by drinking in fresh water have an insignificant energetic effect and hence, energetically, it matters little to the fish whether it drinks or not.

Reflection coefficients and water permeability in rat proximal tubule

1989 ◽  
Vol 257 (4) ◽  
pp. F658-F668 ◽  
Author(s):  
R. Green ◽  
G. Giebisch
Keyword(s):  
Proximal Tubule ◽  
Water Permeability ◽  
Significant Contribution ◽  
Water Flux ◽  
Reflection Coefficients ◽  
Ionic Fluxes ◽  
Peritubular Capillaries ◽  
Solute Movement ◽  
Rat Proximal Tubule ◽  
Net Water Flux

Simultaneous microperfusion of proximal tubules and peritubular capillaries in kidneys of rats anesthetized with Inactin was used to measure reflection coefficients. All perfusates contained cyanide to inhibit active transport; the tubular perfusate was isotonic and the peritubular capillaries were perfused with solutions made hypertonic with NaCl, NaHCO3, L-glucose, or sodium ferrocyanide. Measurements of recollected fluid enabled a precise mean gradient and ionic fluxes to be calculated; net water flux was measured with inulin. Imposed gradients always partly dissipated. Reflection coefficients were 0.59 +/- 0.01 for NaCl, 0.87 +/- 0.04 for NaHCO3-, and 0.96 +/- 0.07 for ferrocyanide, assuming that L-glucose was 1. Water permeability of the proximal tubule was 1,030 microns/s. Ionic permeability of Cl- (21.6 +/- 1.3 X 10(-5) cm/s) was greater than that for Na+ (13.3 +/- 2.7 X 10(-5) cm/s); permeability for L-glucose was 5.4 +/- 1.3 X 10(-5), and for ferrocyanide ions 2.7 +/- 0.9 X 10(-5) cm/s. It is concluded that in rat proximal tubule both NaCl and NaHCO3 have reflection coefficients less than 1.0 and solute asymmetry across the epithelium is a significant driving force for fluid reabsorption. Furthermore the data suggest that there is a significant contribution of solvent drag to solute movement.

Amino Acid Metabolism and Water Transport Across the Seawater Eel Intestine

1988 ◽  
Vol 138 (1) ◽  
pp. 93-106 ◽  
Author(s):  
MASAAKI ANDO
Keyword(s):  
Water Transport ◽  
Water Flux ◽  
Glutamine Metabolism ◽  
Metabolic Inhibitors ◽  
O2 Consumption ◽  
Glutamine Concentration ◽  
Net Water Flux ◽  
Concentration Response Curve ◽  
Glutamine Uptake

To elucidate how intracellular L-alanine enhances water transport across the seawater eel intestine, effects of various metabolic inhibitors were examined. The L-alanine-induced water flux was inhibited by amino-oxyacetate, an inhibitor of aminotransferase. After blocking the synthesis of pyruvate from L-alanine with this drug, water transport was stimulated with pyruvate, whose effects were inhibited by oxythiamine, an inhibitor of pyruvate dehydrogenase. 2,4-Dinitrophenol (DNP) also inhibited the effects of L-alanine. Furthermore, L-alanine enhanced ouabain-sensitive O2 consumption in this tissue, and the enhancement in O2 consumption preceded that in the transepithelial potential difference (PD) and the net water flux. These results indicate that L-alanine is metabolized through the citric acid cycle to produce ATP, and that a metabolic product stimulates ion and water transport. L-Glutamine also seems to be metabolized just like L-alanine because: L-glutamine acted from inside the enterocyte; DNP inhibited the effects of L-glutamine; neither of the effects of L-glutamine and L-alanine were additive but they were mutually complementary; L-glutamine also enhanced ouabainsensitive O2 consumption; and the increment in O2 consumption preceded that in the PD and the net water flux. The effects of L-glutamine on the PD and the net water flux depended on glutamine concentration and the concentration-response curve was of the Michaelis-Menten type, indicating that the rate of L-glutamine uptake into the enterocyte limits the overall rate of L-glutamine metabolism. A regulatory role of amino acids for ion and water transport is discussed.

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.

A mechanism for absorption of sodium chloride solutions from the canine gall bladder

1963 ◽  
Vol 205 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Eugene Grim
Keyword(s):  
Sodium Chloride ◽  
Gall Bladder ◽  
Experimental Observation ◽  
Active Transport ◽  
Transport Mechanism ◽  
Water Flux ◽  
Osmotic Gradient ◽  
Sodium Chloride Solutions ◽  
Osmotic Activity ◽  
Net Water Flux

Absorption of NaCl solutions of different concentrations and of autogenous plasma from the canine gall bladder was studied. Net water flux was linearly related to osmotic activity of the luminal solution, and was positive (in the direction, lumen to blood) up to 420 mOs/liter. Net Na and Cl fluxes were positive above luminal concentrations of 90 and 65 mEq/liter, respectively, and rose with increasing concentration up to that point at which net water flux changed direction; beyond this, they remained essentially constant. Several models for the transport mechanism were considered, with particular emphasis on the question of passive versus active water transport. The only one which was reasonably consistent with experimental observation was as follows. Active transport of solution from lumen to blood by a solution pump like pinocytosis occurred at a rate independent of luminal concentration. The remainder of the water flux was as bulk flow due to the osmotic gradient. Na and Cl transport could be entirely accounted for by movement in the "pinocytotic" fluid and by diffusion in the convective field arising from the osmotic transport of water.

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