scholarly journals Adaptive Changes of the Water Permeability of the Teleostean Gill Epithelium in Relation to External Salinity

1969 ◽  
Vol 51 (2) ◽  
pp. 529-546 ◽  
Author(s):  
R. MOTAIS ◽  
J. ISAIA ◽  
J. C. RANKIN ◽  
J. MAETZ
Keyword(s):  
Fresh Water ◽  
Water Flow ◽  
Sea Water ◽  
Tritiated Water ◽  
Osmotic Gradient ◽  
Ionic Exchange ◽  
Gill Epithelium ◽  
Osmotic Water ◽  
Water Fish ◽  
External Salinity

1. Cannulation of afferent and efferent branchial vessels in the eel permitted studies of tritiated water clearance. It was observed that most of the diffusional water flow occurs through the gills. 2. Diffusional and osmotic water flows have been measured in a fresh-water (Carassius), a marine (Serranus) stenohaline fish and in two euryhaline species (Platichthys and Anguilla) adapted to either fresh water or sea water, and are found to be lower than in any comparable epithelia so far studied. 3. The diffusional water flow deduced from THO turnover is significantly smaller in the sea-water fish. 4. The osmotic water flow, determined indirectly by measuring drinking rate and urine flow, is smaller in the sea-water fishes despite a greater osmotic gradient across the gills. 5. Attempts to compare diffusional and osmotic permeabilities for the gill are hindered by our ignorance of the extent of solute (salt)-solvent interaction in the epitheium. It is suggested that the gill of the fresh-water-adapted fishes is semi permeable, while that of the sea-water teleosts may not be, because of the very high ionic exchange across the gill. 6. The surprisingly low diffusional and osmotic permeabilities of the gill epithelium in sea-water fish may be possibly related to the absence of water-filled pores.

Evidence for transcellular osmotic water flow in rat proximal tubules

1985 ◽  
Vol 249 (1) ◽  
pp. F124-F131 ◽  
Author(s):  
P. A. Preisig ◽  
C. A. Berry
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Water Permeability ◽  
Channel Length ◽  
Osmotic Gradient ◽  
Osmotic Water Permeability ◽  
Osmotic Water ◽  
Major Route ◽  
Osmotic Water Flow

To determine the predominant pathway for transepithelial osmotic water flow, the transepithelial osmotic water permeability [Pf(TE)] and the apparent dimensions of paracellular pores and slits were determined in rat proximal convoluted tubules microperfused in vivo. To measure Pf(TE), tubules were perfused with a hyposmotic, cyanide-containing solution. Pf(TE), calculated from the observed volume flux in response to the measured log mean osmotic gradient, was 0.12-0.15 cm/s, assuming sigmaNaCl equal to 1.0-0.7, respectively. The dimensions of the paracellular pathways were determined using measured sucrose and mannitol permeabilities (nonelectrolytes confined to the extracellular space). These were 0.43 and 0.87 X 10(-5) cm/s, respectively. By using the ratio of these permeabilities, their respective free solution diffusion coefficients and molecular radii, and the Renkin equation, the radius of the nonelectrolyte-permeable pores and the total pore area/cm2 surface area/channel length were calculated to be 1.4 nm and 3.56 cm-1, respectively. Similar calculations for slits yielded a slit half-width of 0.8 nm and a total slit area/cm2 surface area/channel length of 3.16 cm-1. The osmotic water permeability of these nonelectrolyte-permeable pathways was calculated by Poiseuille's law to be 0.0018 cm/s (pores) or 0.0014 cm/s (slits), at most 2% of Pf(TE). We conclude that the nonelectrolyte-permeable pathway in the tight junctions is not the major route of transepithelial osmotic water flow in the rat proximal tubule.

A light microscopic study of the action of sodium orthovanadate on the gills of fresh-water and sea-water eels (Anguilla anguilla L.)

1979 ◽  
Vol 59 (4) ◽  
pp. 859-865 ◽  
Author(s):  
K. F. Kelly ◽  
B. J. S. Pirie ◽  
M. V. Bell ◽  
J. R. Sargent
Keyword(s):  
Light Microscopy ◽  
Fresh Water ◽  
Constant Pressure ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Chloride Cells ◽  
Sodium Orthovanadate ◽  
Central Venous ◽  
Water Fish ◽  
Gill Filaments

Gills of fresh-water and sea-water eels were perfused at a constant pressure with physiological Ringer containing 10−6 M sodium orthovanadate and examined by light microscopy. The secondary gill filaments were markedly vasoconstricted in both freshwater and sea-water fish although the peripheral blood route around the secondary filaments was unaffected. The central venous space in the primary filament was largely unaffected. Significant constriction of both afferent and efferent arteries on the primary filament occurred. We conclude that orthovanadate vasoconstricts eel gills mainly at the level of the secondary filaments. The study also emphasizes that chloride cells are located on both the primary and secondary filaments of fresh-water gills but solely on the primary filaments of sea-water gills.

The effect of hypophysectomy and prolactin treatment on the osmotic water influx into the isolated gills of the Japanese eel (Anguilla japonica)

1977 ◽  
Vol 55 (5) ◽  
pp. 872-876 ◽  
Author(s):  
Mizuho Ogawa
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Anguilla Japonica ◽  
Japanese Eel ◽  
Osmotic Permeability ◽  
Water Influx ◽  
In Vitro Technique ◽  
Osmotic Water

An in vitro technique has been used to measure the osmotic water influx into the isolated gills and the osmotic permeability of the gill surface of the Japanese eel, Anguilla japonica. Hypophysectomy increases both of these measurements. Prolactin injections decrease both osmotic water influx and osmotic permeability to water in both the intact and hypophysectomized eels in fresh water but produce no change in either of these parameters when the fish (either intact or hypophysectomized) are in sea water. The possible role of the pituitary (especially prolactin) in osmoregulation of fishes is discussed and considered in relation to the environmental calcium in sea water.

Nonelectrolyte permeability of the paracellular pathway in Necturus proximal tubule

1975 ◽  
Vol 228 (2) ◽  
pp. 581-595 ◽  
Author(s):  
CA Berry ◽  
EL Boulpaep
Keyword(s):  
Tight Junction ◽  
Proximal Tubule ◽  
Water Flow ◽  
Volume Flow ◽  
Osmotic Gradient ◽  
Osmotic Water ◽  
Net Flux ◽  
Gradient Measurements ◽  
Paracellular Shunt ◽  
Necturus Proximal Tubule

Micropuncture experiments were performed on Necturus proximal tubule using stationary microperfusion and microrecollection techniques. The transepithelial movement of the extracellular marker, sucrose, was used to investigate the passive permeability of the paracellular shunt pathway under steady-state conditions, during spontaneous reabsorption and water flow induced by an external osmotic gradient. Measurements were made of the sucrose permeability (P-s) efflux, net flux, and of net volume flow. True P-s determined in the absence of net volume flow and transepithelial gradient was 0.96 10-6 cm s-1. Both ouabain and isotonic volume expansion decreased shunt P-s. During reabsorption, solute-coupled water flow increased apparent P-s and net sucrose flux equalled efflux. Osmotic water flow from lumen to plasma decreased apparent P-s, with net sucrose flux equal to efflux; whereas osmotic flow from plasma to lumen increased apparent P-s but no net flux was observed. It is concluded that changes in P-s can be interpreted as relative alterations of the tight junction and the lateral spaces and that a portion of the volume flow from lumen to plasma proceeds via the tight junction.

Importance of molecular size and hydrogen bonding in vasopressin-stimulated urea transport

1982 ◽  
Vol 243 (1) ◽  
pp. C27-C34 ◽  
Author(s):  
R. J. Petrucelli ◽  
P. Eggena
Keyword(s):  
Hydrogen Bonding ◽  
Water Flow ◽  
Transport Mechanism ◽  
Tritiated Water ◽  
Molecular Size ◽  
Urea Transport ◽  
Acid Transport ◽  
Glutaraldehyde Fixation ◽  
Osmotic Water ◽  
Osmotic Water Flow

We have employed a variety of urea and thiourea analogues to elucidate further the vasopressin-stimulated urea transport mechanism. In the urea series there was a progressive inhibition of tracer urea transport as cylindrical radius of analogue increased from 2.9 to 3.5 A. Above 3.8 A no inhibition was found. Thiourea analogues were more potent inhibitors for comparable cylindrical radii, and compounds greater than 3.8 A again were not inhibitory. Inhibition was comparable when the inhibitor was moving in the same or opposite directions. Urea transport and its inhibition were preserved in bladders fixed with glutaraldehyde. Osmotic water flow, tritiated water flow, and uric acid transport were not affected by any analogues tested. Analogues of urea and thiourea affected the transport of labeled methylurea and thiourea in a manner similar to their effect on urea. We therefore propose that the urea transport mechanism is a channel with a cylindrical radius between 3.5 and 3.8 A that is capable of interaction with the moving species by hydrogen bonding. This model can account for the selectivity of the vasopressin-stimulated urea transport, its inhibition by urea and thiourea analogues, the facilitated transport of urea, inhibition of tracer urea flux from either the cis or the trans position, and finally the preservation of the urea transport machinery following glutaraldehyde fixation.

The Effects of Prolactin and Divalent Ions on the Permeability to Water of Fundulus Kansae

1970 ◽  
Vol 53 (2) ◽  
pp. 317-327 ◽  
Author(s):  
W. T. W. POTTS ◽  
W. R. FLEMING
Keyword(s):  
Fresh Water ◽  
Calcium Ions ◽  
Sea Water ◽  
Tritiated Water ◽  
Low Doses ◽  
Divalent Ions ◽  
Water Turnover ◽  
Drinking Rate ◽  
Low Concentration ◽  
Ovine Prolactin

1. Measurements have been made of the rate of exchange of tritiated water in both intact and hypophysectomized Fundulus kansae in a variety of media. 2. Hypophysectomy reduces the rate of exchange in fresh water. 3. Low doses (30 mu) of ovine prolactin stimulate water turnover in hypophysectomized fish in fresh water. 4. The rate of exchange declines in both intact and hypophysectomized animals with increasing salinity. 5. Experiments with synthetic solutions show that the decline in the rate of exchange in sea water and in higher salinities is due mainly to the effects of calcium ions. 6. Fishes maintained in synthetic sea water containing a low concentration of calcium have both a higher rate of exchange of tritiated water and a higher drinking rate than fish in normal sea water.

Permeability to water in a tight epithelium: possible modulating action of gap junctions

2004 ◽  
Vol 82 (6) ◽  
pp. 417-421 ◽  
Author(s):  
Gabriel Orce ◽  
Graciela Castillo ◽  
Yolanda Chanampa ◽  
Alejandra Bellomio
Keyword(s):  
Cyclic Amp ◽  
Gap Junctions ◽  
Gap Junction ◽  
Water Flow ◽  
Apical Membrane ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Distal Nephron ◽  
Osmotic Water ◽  
Epithelial Membranes

Osmotic water flow (Jw) across tight distal nephron epithelial membranes increases upon exposure to vasopressin: following binding of the hormone to its receptors, intracellular cyclic AMP concentration increases, leading to insertion of aquaporins in the apical membrane. The involvement of intercellular communication in the process, however, has not been adequately explored. Octanol, 1.2 × 10–3 M, a gap junction inhibitor, significantly reduced Jw (expressed as mg·20 min–1) in isolated toad urinary bladders (a model of the distal nephron) subjected to a transepithelial osmotic gradient and exposed to agents mimicking the vasopressin-triggered mechanism: oxytocin, 50 mIU·mL–1 (from 185.3 ± 28.0, P < 0.001, to 69.0 ± 23.6, P < 0.05; Pdiff < 0.01, n = 6), and cyclic AMP, 2.5 × 10–3 M (from 98.0 ± 32.6, P < 0.02, to 31.0 ± 13.9, NS; Pdiff < 0.05, n = 12), without altering the effect of nystatin, 450 U·mL–1, which increases Jw via a mechanism unrelated to apical aquaporin insertion (163.2 ± 16.3, P < 0.001, in controls vs. 150.3 ± 10.4, P < 0.001, in octanol-treated bladders; Pdiff: NS, n = 6). Another gap junction blocker, carbenoxolone, 2.0 × 10–4 M (CBX), exerted similar effects on the responses to oxytocin, 100 mIU·mL–1, reducing the response from 256.7 ± 33.6, P < 0.001, to 102.7 ± 10.4, P < 0.001; Pdiff < 0.01, n = 6) and nystatin, which was unaffected (95.0 ± 20.9, P < 0.01, vs. 132.0 ± 27.0, P < 0.01; Pdiff: NS, n = 6). Our results suggest that either gap junctions or, alternatively, unapposed gap junction hemichannels, may be important in the regulation of Jw in the isolated toad bladder, by modulating a step in the physiological process leading to increased apical membrane permeability. Key words: Bufo arenarum, toad urinary bladder, water flow, epithelial permeability, n-octanol, carbenoxolone.

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