THE EFFECTS OF VASOPRESSIN ON THE SHORTCIRCUIT CURRENT ACROSS THE WALL OF THE ISOLATED BLADDER OF THE TOAD, BUFO MARINUS

1960 ◽  
Vol 21 (2) ◽  
pp. 161-170 ◽  
Author(s):  
P. J. BENTLEY
Keyword(s):  
Water Transport ◽  
Oxidative Metabolism ◽  
Potassium Concentration ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Metabolic Inhibitors ◽  
Serosal Side ◽  
Divalent Ions ◽  
Ionic Changes ◽  
Toad Bufo

SUMMARY 1. The effects of metabolic inhibitors and ionic changes on the short-circuit current across the toad's bladder have been studied both in the presence and absence of vasopressin. 2. The effects of metabolic inhibitors indicate that the energy for short-circuit current is derived from both glycolysis and oxidative metabolism. 3. Divalent ions play an important part in the maintenance of the resting short-circuit current and of its response to vasopressin. Ca++ or Sr++ are necessary for the former and Ca++ for the latter. 4. Increased concentration of Ca++, Sr++, Mg++ or Ba++ did not inhibit the increment in short-circuit current produced by vasopressin, in contrast to the effect of these ions on water transport. 5. Increase and decrease in potassium concentration inhibited the short-circuit current whether vasopressin was present or not. 6. The correct concentration of sodium on the serosal side of the bladder was necessary to maintain the short-circuit current, but the increment seen when vasopressin was added was not affected by 50% substitution of choline for sodium.

THE EFFECTS OF IONIC CHANGES ON WATER TRANSFER ACROSS THE ISOLATED URINARY BLADDER OF THE TOAD BUFO MARINUS

1959 ◽  
Vol 18 (4) ◽  
pp. 327-333 ◽  
Author(s):  
P. J. BENTLEY
Keyword(s):  
Urinary Bladder ◽  
Potassium Concentration ◽  
Choline Chloride ◽  
Bladder Wall ◽  
Water Transfer ◽  
Bufo Marinus ◽  
Serosal Side ◽  
Ionic Changes ◽  
Toad Bufo

SUMMARY 1. The effects of ionic changes in the bath fluids on water transfer across an in vitro preparation of the urinary bladder of the toad Bufo marinus were investigated. 2. Calcium was necessary to maintain the normal low permeability of the bladder to water in the absence of Pituitrin. Magnesium, strontium and manganese but not barium could substitute for calcium. 3. With low concentration of calcium there was a reduction in the water transfer across the bladder wall in response to Pituitrin and no other divalent ion could substitute for calcium. 4. Exclusion of potassium from the serosal side of the bladder reduced the water transfer in the presence of Pituitrin. Increase in potassium concentration above normal levels also inhibited the response to hormone. When no Pituitrin was present there was no change in water loss from the bladder with alterations in potassium concentration. Absence of potassium from the epithelial side of the bladder had no effect whether Pituitrin was present or not. 5. The presence of sodium on the epithelial side increased the water transfer in response to Pituitrin and neither lithium, choline nor potassium could substitute for it. Replacement of 50% of the sodium chloride on the serosal side of the bladder by choline chloride decreased the water transfer in response to Pituitrin.

Further Observations on the Physiology of Salinity Adaptation in the Crab-Eating Frog (Rana Cancrivora)

1968 ◽  
Vol 49 (1) ◽  
pp. 185-193
Author(s):  
MALCOLM S. GORDON ◽  
VANCE A. TUCKER
Keyword(s):  
Sea Water ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Osmotic Concentration ◽  
Green Toad ◽  
The Face ◽  
Solution Bathing ◽  
Toad Bufo

1. Total rates of urea loss from adult euryhaline crab-eating frogs (Rana cancrivora) adapted to various environmental salinities between fresh water and 80 % sea water increase as salinity increases above 40% sea water. Oxygen consumption is constant in rate in all salinities studied. 2. The presence of urea in the Ringer solution bathing isolated pieces of skin of frogs adapted to 60% sea water increases both the electrical potential and the inwardly directed short-circuit current across the skin. 3. In skeletal muscle cells addition of intracellular solutes maintains tissue hydration in the face of large increases in plasma osmotic concentration in high-salinity media. Changes in the intracellular urea and free amino acid concentrations are primarily responsible for increases in intracellular osmotic concentration. 4. Some implications of these observations are discussed and comparisons made with the euryhaline green toad, Bufo viridis.

Active Transport by the Cecropia Midgut

1968 ◽  
Vol 48 (1) ◽  
pp. 1-12
Author(s):  
W. R. HARVEY ◽  
J. A. HASKELL ◽  
S. NEDERGAARD
Keyword(s):  
Transport Mechanism ◽  
Potassium Concentration ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Potassium Transport ◽  
Nernst Equation ◽  
Tissue Concentrations ◽  
Sodium Magnesium ◽  
Lines Of Evidence ◽  
Stimulation Of

1. From two lines of evidence, we conclude that the potassium transport gives rise directly to the midgut potential, i.e. that the active potassium transport mechanism is electrogenic. 2. First, diffusion potentials of neither potassium, sodium, magnesium, calcium, nor chloride could give rise to the large midgut potential if values for tissue concentrations are accepted for their respective activities in the epithelium. 3. Secondly, no externally added cation other than potassium is required to sustain either the potential or short circuit current, no specific anion is required, and no metabolic ion is known to be produced in sufficient amount to act as a counter ion for potassium in a non-electrogenic process. 4. Changes in the concentration of potassium on the blood-side of the midgut always lead to changes in potential in the direction predicted by the Nernst equation. Moreover, a tenfold change in potassium concentration leads to the expected 59 mV. potential change provided that the prior midgut potential is at least 130 mV. This effect could be attributed either to the stimulation of an electrogenic potassium pump or to a potassium diffusion potential across the blood-side barrier.

Active and passive chloride movements across isolated amphibian skin

1964 ◽  
Vol 207 (5) ◽  
pp. 1010-1014 ◽  
Author(s):  
José A. Zadunaisky ◽  
Felisa W. De Fisch
Keyword(s):  
Antidiuretic Hormone ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Ions ◽  
Amphibian Skin ◽  
Chloride Flux ◽  
Bufo Arenarum ◽  
Sodium Loss ◽  
Toad Bufo

Several aspects of chloride passage through isolated amphibian skin were studied. The chloride transport performed by the skin of the frog Leptodactylus ocellatus or the passive chloride fluxes observed in the skin of the toad Bufo arenarum Hensel are not affected by antidiuretic hormone. The chloride transport produces a negative potential and a short-circuit current in sodium-free solutions, though the unidirectional fluxes of chloride are greatly reduced under these conditions. The short-circuit current due to the chloride transport is smaller than the net chloride flux. It was found that this disagreement could be ascribed to a loss of sodium toward the inside from the sodium pool of the skin. Antidiuretic hormone did not affect the chloride current, nor the sodium loss from the skin. The isolated skin of the toad Bufo arenarum Hensel does not transport chloride ions. Thus the active transport of chloride observed in isolated skins of the frog Leptodactylus ocellatus does not depend on environmental conditions, since both animals live in the same surroundings.

Avian cecum: role of glucose and volatile fatty acids in transepithelial ion transport

1991 ◽  
Vol 260 (5) ◽  
pp. G703-G710 ◽  
Author(s):  
B. R. Grubb
Keyword(s):  
Fatty Acids ◽  
Ion Transport ◽  
Volatile Fatty Acids ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Na Transport ◽  
Cl Secretion ◽  
Mucosal Side

In the fowl cecum in vitro, the influence of glucose and the three most prevalent naturally occurring volatile fatty acids (acetate, propionate, butyrate) on short-circuit current (Isc), electrical resistance, and transport of Na and Cl was determined. When glucose, acetate, or butyrate was present, ion transport was characterized by electrogenic Na absorption, greater than 65% of which was amiloride inhibitable, and Cl secretion, which also was electrogenic. Isc could be completely accounted for by net fluxes of Na and Cl. When glucose, acetate, or butyrate (10 mM both sides) was included in the incubation medium, cecal tissue maintained its Isc and a constant rate of net Na absorption and Cl secretion for a 5-h period. When no substrate was present or propionate was included in the medium, a marked fall in Isc and net Na and Cl fluxes was seen. Glucose caused an increase in Isc when added only to the serosal side. As 3-O-methylglucose (not metabolized) was not effective in stimulating Isc of the cecum (serosal or mucosal addition), it appeared that glucose increased Isc by acting as an energy substrate for active Na transport. Acetate and butyrate appeared to be equally effective in stimulating Na transport and Isc when placed on either side of the membrane. When the preparation was supplied with glucose (serosal side) and acetate was added to the mucosal side, no further stimulation of Isc occurred. Thus it appeared that acetate and butyrate were acting as substrates for active Na transport rather than stimulating Na transport by some other mechanism such as a cotransport with Na.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals ION TRANSPORT IN THE INTESTINE OF ANGUILLA ANGUILLA: GRADIENTS AND TRANSLOCATORS

1994 ◽  
Vol 193 (1) ◽  
pp. 97-117 ◽  
Author(s):  
P Marvão ◽  
M G Emílio ◽  
K Gil Ferreira ◽  
P L Fernandes ◽  
H Gil Ferreira
Keyword(s):  
Short Circuit ◽  
Basolateral Membrane ◽  
Specific Inhibitor ◽  
Anguilla Anguilla ◽  
Short Circuit Current ◽  
Inhibitory Effect ◽  
Serosal Side ◽  
Sodium Dependent ◽  
Transport Inhibitors ◽  
Experimental Strategies

The transport of Na+, K+ and Cl- across the isolated epithelium of the eel intestine was studied using a combination of four experimental strategies: short-circuiting, measurements of intracellular potentials and ion concentrations, application of a variety of transport inhibitors and measurement of unidirectional fluxes with radioactive tracers. When short-circuited, the system performs a net transport of Cl- and Na+ towards the blood side, with a stoichiometry approaching 2, and a much smaller net transport of K+ towards the lumen. The system is totally driven by the sodium pump located in the basolateral barrier and the main coupling between the fluxes of the three ions is through the operation of a furosemide-sensitive transporter in the apical barrier, probably a 2Cl-/Na+/K+ symporter. The inhibitory effect of DIDS and picrylsulphonic acid on the short-circuit current, when added to the serosal side, suggests the presence of a sodium-dependent anionic shuttle located in the basolateral membrane. The short-circuit current is inhibited by H25, a non-specific inhibitor of the K+/Cl- symport, added to the serosal side. This effect occurs after a delay of at least 5 min and may result from the diffusion of the drug to the apical barrier, where it blocks the 2Cl-/Na+/K+ symport with much higher affinity.

Characteristics of H+ current transients induced by adverse H+ gradient pulses in toad bladder

1987 ◽  
Vol 253 (4) ◽  
pp. F606-F612
Author(s):  
A. C. Nero ◽  
J. H. Schwartz ◽  
M. R. Furtado
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Ph Gradient ◽  
Toad Bladder ◽  
Serosal Side ◽  
Solution Ph ◽  
Initial Values ◽  
Cell Ph ◽  
Before And After ◽  
Current Transients

Acidification in the toad bladder occurs as a result of electrogenic H+ secretion (JH). When a pH gradient is applied in a stepwise fashion in the absence of exogenous CO2, JH decreases linearly with the mucosal (M) solution pH and is null when pHm is approximately 4.5. When pHm is returned to initial values (7.4) in a stepwise fashion, JH increases linearly with pHm. However, on this return, higher values of JH are initially obtained. To investigate this hysteresis, hemibladders mounted in chambers were used to measure the change in the H+ current before and after acid pulses were applied to the mucosal solution. In the absence of exogenous CO2, the application of graded acid pulses to mucosa for 1, 2, 4, and 8 min resulted in a graded decrease in JH. The restoration of pHm to 7.4 was followed by an immediate transient overshoot of reversed short-circuit current (Irsc), which was related to the time of exposure and the magnitude of the acid pulse. The longer the acid pulse or the larger the pulse, the greater the Irsc overshoot. The addition of protonophores, dinitrophenol, or salicylate, into the mucosal solution enhanced this overshoot. Similar Irsc overshoots could be obtained with the application of pulses of adverse electrical gradients. Introduction of exogenous CO2 into the system (3%) completely inhibited the overshoot in JH after an acid pulse. In conclusion, when pHm is decreased JH is reduced and the cell pH presumably decreases because of continued exit of alkali at the serosal side of the cell and entry of H+ from the mucosal solution. The decrease in cell pH then triggers the pump to produce a sharp overshoot in JH when pHm returns to 7.4.

Ileal mucosal cyclic AMP and Cl secretion: serosal vs. mucosal addition of cholera toxin.

1977 ◽  
Vol 232 (2) ◽  
pp. E210 ◽  
Author(s):  
H E Sheerin ◽  
M Field
Keyword(s):  
Cyclic Amp ◽  
Ion Transport ◽  
Cholera Toxin ◽  
Short Circuit ◽  
Electrical Conductance ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Ileal Mucosa ◽  
Camp Content ◽  
Mucosal Side

Changes in ion transport and cyclic AMP (cAMP) concentration produced by addition of cholera toxin to the serosal side of isolated rabbit ileal mucosa (CTs) were compared to the changes produced by addition to the mucosal side (CTm). CTs increased short-circuit current (SCC) as did CTm but it did so more slowly. CTs, unlike CTm, did not significantly decrease electrical conductance. Inhibition of the SCC response to theophylline, a measure of preexisting secretion, was almost complete 180 min after CTm but was not yet significant 180 min after CTs. Longer (280 min) after CTs, the SCC response to theophylline was reduced by 59%, a significant reduction but less than that caused by CTm. A statistically significant change in net Cl flux could not be demonstrated after CTs, although at 280 min the measured flux was halfway between the fluxes for control and CTm tissues. Cyclic AMP concentrations were determined at 190 min, 10 min after addition of theophylline. CTs, despite little or no effect on ion transport, increased cAMP to the same level as did CTm, and the effect on cAMP of adding toxin to both sides was additive. We conclude that 1) active secretion is probably stimulated by cholera toxin added on the serosal side, although more slowly than after addition to the mucosal side and 2) much of the toxin-stimulated cAMP content of the mucosa is not coupled to secretion.

Chloride transport in glands of frog skin

1983 ◽  
Vol 244 (3) ◽  
pp. C221-C226 ◽  
Author(s):  
I. G. Thompson ◽  
J. W. Mills
Keyword(s):  
Frog Skin ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Skin Glands ◽  
Frog Skin Glands ◽  
Beta Adrenergic Agonist

The effects of beta-adrenergic stimulation on the bidirectional fluxes of Na+ and Cl- across the frog skin glands were determined. Isoproterenol elicited net serosal-to-mucosal fluxes of both Na+ (JNanet) and Cl- (JClnet) equal to 0.19 +/- 0.05 (SE) and 0.57 +/- 0.05 mueq X cm-2 X h-1, respectively. The residual current (JClnet - JNanet) of 0.38 +/- 0.05 mueq X cm-2 X h-1 closely approximates the isoproterenol-induced short-circuit current of 0.30 +/- 0.04 mueq X cm-2 X h-1. Furosemide added to the serosal side prior to isoproterenol inhibited the isoproterenol-induced net fluxes of both Na+ and Cl-. The addition of dibutyryl cAMP and 3-isobutyl-1-methylxanthine to the serosal side mimicked the action of isoproterenol by stimulating glandular short-circuit current. We conclude that an active Cl(-)-transport mechanism resides in the frog skin glands and is 1) stimulated by a beta-adrenergic agonist (its action is mimicked by cAMP) and 2) inhibited by the loop diuretic furosemide.

Effects of 3'-deoxycytidine on rRNA synthesis in toad bladder: analysis of response to aldosterone

1977 ◽  
Vol 232 (5) ◽  
pp. C174-C179 ◽  
Author(s):  
B. C. Rossier ◽  
P. A. Wilce ◽  
J. F. Inciardi ◽  
F. K. Yoshimura ◽  
I. S. Edelman
Keyword(s):  
Urinary Bladder ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Early Response ◽  
Rrna Synthesis ◽  
Mrna Synthesis ◽  
Na Transport ◽  
Polyadenylated Rna ◽  
Toad Bufo

Previous studies showed that aldosterone augments transepithelial active Na+ transport and the incorporation of [3H]uridine into polyadenylated RNA (poly(A)(+)-RNA) (putatively mRNA) early in the latent period. Soon thereafter, incorporation of [methyl-14C] groups, as well as [3H]uridine into rRNA is also increased. To evaluate the role of rRNA in mineralocorticoid action, the inhibitor 3'-deoxycytidine was used in studies on the urinary bladder of the toad Bufo marinus. 3'-deoxycytidine suppressed the incorporation of [methyl-14C] and [3H]uridine into nuclear precursors of rRNA and subunits of cytoplasmic rRNA. In contrast, 3'-deoxycytidine inhibited incorporation of ]3H]uridine into cytoplasmic poly(A)(+)-RNA minimally. In control experiments, 3'-deoxycytidine had no significant effect on Na+ transport, measured as the short-circuit current (scc), when given alone. 3'-Deoxycytidine also had no significant effect on the aldosterone-dependent increase in scc. In the presence of 3'-deoxycytidine, aldosterone enhanced both the scc and the incorporation of [3H]uridine into poly(A)(+)-RNA significantly. We conclude that during the first 3 h, the mineralocorticoid action of aldosterone is not sensitive to inhibition of rRNA synthesis. Previous studies, however, implicate mRNA synthesis in this early response.

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