An electrophysiological study of the salt gland of the herring gull

1962 ◽  
Vol 202 (3) ◽  
pp. 597-600 ◽  
Author(s):  
S. Thesleff ◽  
K. Schmidt-Nielsen
Keyword(s):  
Sodium Chloride ◽  
Active Transport ◽  
Sodium Transport ◽  
Electrophysiological Study ◽  
Salt Gland ◽  
Gland Secretion ◽  
Herring Gull ◽  
Active Sodium ◽  
Positive Potential ◽  
Active Sodium Transport

When the salt gland of the herring gull excretes sodium chloride the duct of the gland becomes positive relative to the blood. Strophanthin, an inhibitor of active sodium transport, prevents the establishment of the positive potential and also blocks gland secretion. The findings suggest that an active transport of sodium from the blood to the gland lumen may be a primary secretory mechanism.

Ion selectivity and proximal salt reabsorption

1978 ◽  
Vol 235 (3) ◽  
pp. F234-F245 ◽  
Author(s):  
C. A. Berry ◽  
D. G. Warnock ◽  
F. C. Rector
Keyword(s):  
Active Transport ◽  
Sodium Transport ◽  
Ion Selectivity ◽  
Electrical Potential ◽  
Great Majority ◽  
Active Sodium ◽  
Experimental Conditions ◽  
Active Sodium Transport ◽  
Luminal Perfusion ◽  
The Difference

Electrophysiological techniques were used in isolated perfused superficial (S) and juxtamedullary (JM) rabbit proximal convoluted tubules (PCT) to examine the relative sodium-to-chloride (PNa/PCl) and bicarbonate-to-chloride (PHCO3/PCl) permeability ratios. We found that the great majority of PCT are sodium selective and that PHCO3/PCl depends on the experimental conditions. In the presence of active sodium transport, PHCO3/PCl is high and increases with PNa/PCl. When PHCO3/PCl is determined after inhibition of active sodium transport or at 25 degrees C, PHCO3/PCl approximates the free solution anion mobility ratio of 0.5 and is independent of PNa/PCl. The difference between PHCO3/PCl determined in the presence of and in the absence of active transport suggests that the lowering of bath bicarbonate concentration in the presence of active transport changes both paracellular and transcellular current flow. In addition, we found that during luminal perfusion with high chloride, low bicarbonate, organic solute-free solutions, the transepithelial electrical potential depends on PNa/PCl and PHCO3/PCl. This potential is approximately 4.0 mV in S PCT with low PNa/PCl and falls progressively to zero in JM PCT with high PNa/PCl. From these data we conclude that anion concentration gradients drive an important diffusive flux of sodium chloride through the paracellular pathway only in PCT with low PNa/PCl ratios.

Bicarbonate ions in active sodium transport across toad bladder

1977 ◽  
Vol 232 (3) ◽  
pp. F210-F214
Author(s):  
J. S. Chen ◽  
M. Walser
Keyword(s):  
Active Transport ◽  
Sodium Transport ◽  
Short Circuit ◽  
Active Sodium ◽  
Empirical Constant ◽  
Normal Medium ◽  
Spontaneous Potential ◽  
Active Sodium Transport ◽  
Bicarbonate Ions ◽  
Transport Path

The conductance, ga, and electromotive force, E, of active ion transport across toad bladders mounted as sacs were estimated from electrical measurements made before and after addition of sufficient ouabain (1.89 X 10(-3) M) to eliminate spontaneous potential. The ratio of net sodium transport (estimated from bidirectional fluxes) to external current in bladders voltage clamped to 0 mV was significantly less than unity in a normal medium containing HCO3- and Cl- ions, and also when Cl- was replaced with SO42-. However, when acetazolamide was added or when HCO3- was replaced by phosphate, short-circuit current and net sodium transport became equal. Spontaneous potential, E, and ga were all reduced about 20% by these maneuvers. The response of bidirectional sodium fluxes to voltage clamping at 0 mV or 120 mV in a bicarbonate-free medium was otherwise similar to that observed in a normal medium: net flux varied linearly with potential and calculated fluxes in the active transport path indicated a value significantly greater than unity for the empirical constant Q in the equation for change in the flux ratio, f, with change in potential, psi, viz., delta ln f = Q(ZF/RT)delta psi, similar to the high value for this constant that we have found in a bicarbonate-containing medium. We conclude that bicarbonate ions facilitate active sodium transport and also may be actively transported from serosa to mucosa in Dominican toads. However, coupling between bicarbonate and sodium fluxes does not account for the high value for Q for sodium in the active transport path.

DECREASED EFFECTIVENESS OF ALDOSTERONE ON ACTIVE SODIUM TRANSPORT BY THE ISOLATED TOAD BLADDER IN THE PRESENCE OF OTHER STEROIDS

1964 ◽  
Vol 47 (3) ◽  
pp. 419-432 ◽  
Author(s):  
Jean Crabbé
Keyword(s):  
Active Transport ◽  
Sodium Transport ◽  
Concentration Ratio ◽  
Effective Concentration ◽  
Toad Bladder ◽  
Active Sodium ◽  
Active Sodium Transport ◽  
Hormonal Effect ◽  
Serosal Surface

ABSTRACT Aldosterone can stimulate the active transport of sodium by the isolated toad bladder in vitro. Corticosterone, cortisol, 17β-oestradiol and progesterone had no such effect despite incubation of the preparation with more than 100 times the smallest effective concentration of aldosterone. When the serosal surface of the membranes was exposed to 10 μg% d-aldosterone combined with 100 times this concentration of corticosterone, cortisol or progesterone, the stimulating action of aldosterone was reduced. Spirolactone SC 9420 failed to exert by itself a significant effect on the isolated toad bladder in vitro, but this compound blocked the stimulation by aldosterone of active sodium transport in vitro when present at concentrations 50 times those of aldosterone. When the concentration ratio was 10:1, a hormonal effect could be demonstrated, except at the highest concentration of the drug used.

Micropuncture study of composition of proximal and distal tubular fluid in rat kidney

1963 ◽  
Vol 204 (4) ◽  
pp. 527-531 ◽  
Author(s):  
Karl J. Ullrich ◽  
Bodil Schmidt-Nielsen ◽  
Roberta O'Dell ◽  
Gundula Pehling ◽  
Carl W. Gottschalk ◽  
...  
Keyword(s):  
Sodium Transport ◽  
Rat Kidney ◽  
Active Sodium ◽  
Osmotic Diuresis ◽  
Active Sodium Transport ◽  
Anesthetized Rats ◽  
Micropuncture Study

Fluid was collected by micropuncture from proximal and distal convolutions of anesthetized rats and analyzed for inulin, sodium, urea, and total osmotically active solute. The proximal fluid/plasma (F/P) sodium ratio was not significantly different from unity in antidiuretic animals, but was as low as 0.78 during mannitol diuresis. The distal F/P sodium ratio averaged 0.62 in antidiuresis, and 0.24 during osmotic diuresis. The data are interpreted to indicate active sodium transport by both proximal and distal convolutions. The F/P ratios for inulin, urea, and total osmotically active solute are in general agreement with previous studies.

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