Capacitance, short-circuit current and osmotic water flow across different regions of the isolated toad skin

1992 ◽  
Vol 162 (8) ◽  
pp. 707-713 ◽  
Author(s):  
Cathleen A. Baker ◽  
Stanley D. Hillyard
Keyword(s):  
Water Flow ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Toad Skin ◽  
Osmotic Water ◽  
Osmotic Water Flow

Effects of prostacyclin on short-circuit current and water flow in the toad urinary bladder

1983 ◽  
Vol 244 (3) ◽  
pp. F270-F277
Author(s):  
T. Pohlman ◽  
J. Yates ◽  
P. Needleman ◽  
S. Klahr
Keyword(s):  
Urinary Bladder ◽  
Water Transport ◽  
Water Flow ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Camp Production ◽  
Acid Product ◽  
Osmotic Water ◽  
Osmotic Water Flow

The effects of prostaglandins of the E series on sodium and water transport have been studied extensively. PGE2 has been shown to inhibit the increase in osmotic water flow produced by vasopressin and to stimulate short-circuit current (SCC) in the toad bladder. On the other hand, the effects of prostacyclin (PGI2), an arachidonic acid product, on sodium and water transport have not been extensively evaluated. The present studies describe the effects of PGI2 on basal and vasopressin-stimulated osmotic water flow and on SCC in the urinary bladder of the toad. Studies were performed in the absence or presence of indomethacin. PGI2 in the absence of indomethacin had no effect on basal or vasopressin-stimulated osmotic water flow. When indomethacin was present, thereby eliminating intrinsic prostaglandin biosynthesis, PGI2 inhibited basal but not vasopressin-stimulated osmotic water flow. PGI2 increased SCC in the presence or absence of indomethacin. 6-keto PGF1 alpha, the stable metabolite of PGI2, had no effect on SCC. PGI2 stimulated cAMP production in isolated toad bladder epithelial cells. 2',5'-Dideoxyadenosine, an inhibitor of cAMP production, blocked the increase in SCC produced by PGI2, suggesting that the effects of this compound on SCC are mediated via cAMP.

Transport properties of toad kidney epithelia in culture

1981 ◽  
Vol 241 (3) ◽  
pp. C154-C159 ◽  
Author(s):  
F. M. Perkins ◽  
J. S. Handler
Keyword(s):  
Electrical Resistance ◽  
Hormonal Regulation ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Transepithelial Electrical Resistance ◽  
Apical Surface ◽  
Osmotic Water ◽  
Sodium Flux ◽  
Regulation Of Transport ◽  
Osmotic Water Flow

The characteristics of a continuous line of toad kidney epithelial cells (A6) are described. These cells form a monolayer epithelium of high transepithelial electrical resistance (about 5,000 omega . cm2). The cells generate a transepithelial potential difference (apical surface negative) of about 9 mV. The short-circuit current is equivalent to net sodium flux. Net sodium flux is stimulated by aldosterone and by analogues of cAMP. The stimulation is readily reversible. Neither urea permeability nor osmotic water flow is altered by analogues of cAMP. Amiloride eliminates 90% of the short-circuit current. Thus A6 cells form an epithelium with several differentiated properties including hormonal regulation of transport.

Effect of rat cardionatrin I (rat ANF 99–126) on the response of toad skin to angiotensin II

1989 ◽  
Vol 67 (4) ◽  
pp. 362-365 ◽  
Author(s):  
Alfredo Coviello ◽  
Marcelo O. Soria ◽  
Maria C. Proto ◽  
Dora M. Berman ◽  
Silvia S. Gamundi ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Atrial Natriuretic Factor ◽  
Epithelial Transport ◽  
Short Circuit ◽  
Extracellular Fluid ◽  
Short Circuit Current ◽  
Osmotic Water Permeability ◽  
Toad Skin ◽  
Osmotic Water ◽  
Atrial Natriuretic

The atrial natriuretic peptide cardionatrin I (cardionatrin I is ANF 99–126) was used in studies directed to assess its effects on osmotic water permeability (Posm) and short-circuit current (SCC) in isolated toad skin. Results showed that ANF 99–126 (10−7 M) added to the dermal side of the skin had no effect on basal Posm or SCC. However, ANF 99–126 (3.3 × 10−8 M) was able to produce a 50% reversible inhibition of the maximal Posm response to angiotensin II (AH) (3.2 × 10−8 M). These effects were seen when the skins were preincubated with ANF 99–126 for 10 min or less before the addition of AII Longer preincubation appeared to inactivate ANF 99–126 through proteolysis. ANF 99–126 (10−7 M) failed to inhibit the SCC response to AII (10−5 M) in toad skin. These results are compatible with a modulatory function for ANF on several systems including those involved in the regulation of extracellular fluid volume.Key words: atrial natriuretic factor, natriuretic peptides, epithelial transport.

Effect of Growth Hormone on Sodium Transport and Osmotic Water Flow Across Toad Skin

1974 ◽  
Vol 6 (02) ◽  
pp. 129-132 ◽  
Author(s):  
R. Rabkin ◽  
Margaret Swann ◽  
D. Shapiro ◽  
L. Isaacson
Keyword(s):  
Growth Hormone ◽  
Water Flow ◽  
Sodium Transport ◽  
Toad Skin ◽  
Osmotic Water ◽  
Osmotic Water Flow

8-BrcAMP-induced capacitance and transport of H2O and Na in skin and urinary bladder of urodele amphibians

1989 ◽  
Vol 256 (6) ◽  
pp. C1145-C1152 ◽  
Author(s):  
R. B. Silver ◽  
L. G. Palmer
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Constant Current ◽  
Voltage Response ◽  
Tiger Salamander ◽  
Current Pulses ◽  
Osmotic Water ◽  
Transepithelial Voltage ◽  
Mucosal Side ◽  
Osmotic Water Flow

The effects of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) on capacitance (C), osmotic water flow (Jv), and amiloride-sensitive short-circuit current (INa) were studied in bladder and skin derived from the tiger salamander (aquatic and postmetamorphosed terrestrial phase). 8-BrcAMP-dependent increases in C, measured from the transepithelial voltage response to constant current pulses, occurred in aquatic (delta C = 44%) and terrestrial (delta C = 61%) bladders and terrestrial skin (delta C = 19%). Jv (200-mosM gradient, mucosal side hypotonic) was observed in the bladders and was further enhanced by addition of 8-BrcAMP [10(-3) M; delta Jv = 0.42 microliter.min-1.microF-1 (aquatic) and 0.32 microliter.min-1.microF-1 (terrestrial)]. The aquatic and terrestrial skins were relatively impermeable to water, but the terrestrial skin showed a small response to 8-BrcAMP (delta Jv = 0.04 microliter.min-1.microF-1). 8-BrcAMP-mediated natriferic responses were observed in aquatic bladder (delta INa = 62%) and terrestrial skin (delta INa = 105%). Antidiuretic hormone (ADH)-induced Jv was also observed in the aquatic bladder (delta Jv = 0.33 microliter.min-1.microF-1) and was similar to the 8-BrcAMP-mediated Jv measured in this tissue. The terrestrial bladder displayed a more vigorous response to 8-BrcAMP than to ADH (delta JvADH = 0.09 microliter.min-1.microF-1 and delta Jv8-BrcAMP = 0.32 microliter.min-1.microF-1), suggesting that diminished sensitivity to ADH accompanies the transition from water to land in this species.

Polyclonal antibodies in study of ADH-induced water channels in frog urinary bladder

1991 ◽  
Vol 261 (3) ◽  
pp. F437-F442
Author(s):  
G. Valenti ◽  
G. Calamita ◽  
M. Svelto
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Apical Membrane ◽  
Polyclonal Antibodies ◽  
Immune Serum ◽  
Frog Urinary Bladder ◽  
Hormonal Stimulation ◽  
Osmotic Water ◽  
Triton X ◽  
Osmotic Water Flow

It is now generally accepted that changes in water permeability in anti-diuretic hormone (ADH)-responsive target epithelial cells result from the insertion in the plasma apical membrane of new components that contain channels for water. The specificity of these channels suggests that they are formed by intrinsic proteins having access to both facies and spanning the whole membrane. We have previously shown that Triton X-100 apical extracts from ADH-stimulated frog urinary bladder contain some proteins inserted under hormonal stimulation. In the present study we have developed polyclonal antibodies using Triton X-100 extract as an immunogen. After considering the inhibitory effect exerted by the whole immune serum on the osmotic water flow, we used different adsorption steps to select, from the immune serum, antibodies to apical membrane proteins inserted in response to the hormone. Immunoblot analysis of these selected antibodies shows that they recognize seven to eight proteins, of which 55-, 35-, 26-, and 17-kDa proteins are always present. Antibodies to these four proteins, affinity purified on nitrocellulose sheets, inhibited ADH-induced osmotic water flow. Altogether these results strongly suggest that proteins of 55, 35, 26, and 17 kDa (or at least one of them) are likely to be involved in the mechanism of water transport.

scholarly journals A model of electrodiffusion and osmotic water flow and its energetic structure

2011 ◽  
Vol 240 (22) ◽  
pp. 1835-1852 ◽  
Author(s):  
Yoichiro Mori ◽  
Chun Liu ◽  
Robert S. Eisenberg
Keyword(s):  
Water Flow ◽  
Osmotic Water ◽  
Osmotic Water Flow

Ultrastructural changes in isolated perfused proximal tubules during osmotic water flow

1987 ◽  
Vol 253 (6) ◽  
pp. F1091-F1104
Author(s):  
A. B. Maunsbach ◽  
S. Tripathi ◽  
E. L. Boulpaep
Keyword(s):  
Cell Volume ◽  
Water Flow ◽  
Streaming Potential ◽  
Volume Density ◽  
Proximal Tubules ◽  
Ultrastructural Changes ◽  
Organic Substrates ◽  
Osmotic Water ◽  
Cell Volumes ◽  
Osmotic Water Flow

Steady-state effects of osmotic gradients on extracellular spaces and cell volumes were studied by ultrastructural morphometry in isolated perfused Ambystoma proximal tubules. Solute clamping, high-resolution pressure and flow control of lumen and bath solutions were all ascertained before and during fixation. Isosmotic removal of organic substrates in the lumen reversibly abolished transport, as confirmed by transepithelial potential decrease from -4.7 +/- 0.5 to -0.5 +/- 0.2 mV (n = 8) but had no effect on ultrastructural parameters. The walls of the extracellular spaces are therefore not deformed by spontaneous solute-coupled water transport. A hyperosmolar lumen generated a streaming potential of -1.56 +/- 0.15 mV (n = 8), reduced cell volume to 65%, reduced lateral intercellular space (LIS) volume to 20%, and LIS volume density to 29% of control without significant effects on the volume of the basal extracellular labyrinth (BEL). A hyperosmolar bath generated a streaming potential of +1.96 +/- 0.30 mV (n = 7), reduced cell volume to 68%, and increased LIS volume density to 236% of control. BEL volume was 55% larger during lumen-to-bath flow than during bath-to-lumen flow. Because cell volume reduction is very similar for both directions of osmotic water flow, the oppositely directed volume changes in the extracellular spaces are secondary to transepithelial water flow. The greater change in volume of LIS compared with BEL indicates that the outermost parts of the LIS are more resistive to transepithelial water flow than the slitlike communications of the BEL with the peritubular space.

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