Renal Response of Euryhaline Toad (Bufo viridis) to Acute Immersion in Tap Water, NaCl, or Urea Solutions

1999 ◽  
Vol 72 (2) ◽  
pp. 227-237 ◽  
Author(s):  
Shlomo Shpun ◽  
Uri Katz
Keyword(s):  
Tap Water ◽  
Bufo Viridis ◽  
Renal Response ◽  
Toad Bufo

Urea transport across urinary bladder and salt acclimation in toad (Bufo viridis)

1990 ◽  
Vol 258 (4) ◽  
pp. R883-R888 ◽  
Author(s):  
S. Shpun ◽  
U. Katz
Keyword(s):  
Urinary Bladder ◽  
Tap Water ◽  
Water Flux ◽  
Inhibitory Effect ◽  
Facilitated Diffusion ◽  
Urea Transport ◽  
Bufo Viridis ◽  
Salt Acclimation ◽  
Osmotic Water ◽  
Toad Bufo

The fluxes of urea across the urinary bladder of the toad Bufo viridis have been studied under conditions of acclimation to tap water or 500 mosM NaCl solution. The [14C]urea fluxes were measured simultaneously with [3H]inulin to test for nonspecific leakage. The fluxes are quite high (Ktrans = 75 x 10(-7) cm/s at 5 mmol/l urea) and are similar in either the mucosal-to-serosal or the opposite direction. “Summer” rates were five to six times higher than the “winter” rates. Antidiuretic hormone (ADH), theophylline, and forskolin increased the fluxes to variable degrees (two to five times), similar in the two acclimation conditions. Phloretin inhibited the urea fluxes by nearly 50%. 1,3-Dimethylurea and thiourea, but not acetamide, competed with the urea fluxes effectively. The fluxes of urea were not affected by the osmotic water flow, although both responded to ADH. It is concluded that urea transport across the urinary bladder of B. viridis is by facilitated diffusion through a specific pathway independent of water flux. The inhibitory effect of the structural analogues on the urea flux was affected by salt acclimation, whereas most other characteristics did not differ significantly at 5 mmol/l external urea under the two conditions of acclimation.

NaCl adaptation in Rana ridibunda and a comparison with the euryhaline toad Bufo viridis

1975 ◽  
Vol 63 (3) ◽  
pp. 763-773
Author(s):  
U. Katz
Keyword(s):  
Water Uptake ◽  
Sodium Transport ◽  
Tap Water ◽  
Physiological Adaptation ◽  
Salt Adaptation ◽  
Osmotic Gradient ◽  
Rana Ridibunda ◽  
Bufo Viridis ◽  
Water Frogs ◽  
Toad Bufo

The physiological adaptation of the frog Rana ridibunda to saline environment was studied. It was found that blood was always hypertonic to the external solution, but at the highest salinity tolerated (i.e. 300 mOsM) the osmotic gradient across the skin was nearly abolished. Water uptake by the living frog remained unchanged, whereas sodium transport across the skin decreased markedly. Neurohypophyseal hormone increased water uptake and sodium transport to levels similar to those in tap water frogs. Water content of the tissues was not affected by saline adaptation, although it varied appreciably under acute conditions. Oxygen consumption increased in dehydrated frogs, but not in adapted ones. The results are discussed and compared to the euryhaline toad Bufo viridis; the importance of high urea levels for high salt adaptation is stressed.

The Effect of Salt Adaptation and Amiloride on the In Vivo Acid-Base Status of the Euryhaline Toad Bufo Viridis

1981 ◽  
Vol 93 (1) ◽  
pp. 93-99
Author(s):  
U. KATZ
Keyword(s):  
Tap Water ◽  
Salt Adaptation ◽  
Acid Base ◽  
Bufo Viridis ◽  
Acid Base Status ◽  
Simultaneous Decrease ◽  
Toad Bufo

1. The acid-base status of the blood of the toad Bufo viridis was studied during adaptation to high salinity and in tap water containing amiloride. 2. Both salt adaptation and immersion for 2-3 days in 5 x10−4 M amiloride in tap water resulted in a decrease in blood pH (from 7.720 ± 0.026 in tap water to 7.456±0.051 in 500 mOsm NaCl-adapted toads; mean ± S.E.), and a simultaneous decrease in the concentration of HCO3- (from 17.8 ±1.4 in tap water to 9.5±1.2 in salt-adapted toads). 3. In vitro determination of Na+/H+ exchange across the skin showed a 1:1 relation in skins from tap-water-adapted toads; this exchange was inhibited by amiloride. H+ secretion was abolished in skins from salt-adapted toads and the uptake of sodium was reduced.

On a New Species of the Genus Cosmocerca Diesing, 1861 from a Toad, Bufo viridis, in Kashmir

1959 ◽  
Vol 33 (2-3) ◽  
pp. 161-170 ◽  
Author(s):  
D. N. Fotedar
Keyword(s):  
New Species ◽  
Bufo Viridis ◽  
Male Tail ◽  
Toad Bufo ◽  
A New Species

1. A new species, Cosmocerca kashmirensis n.sp. from the toad, Bufo viridis, in Kashmir, is described. The new species has 19 plectanes in the male tail, of which 3 plectanes are simple rosettes and resemble the compound caudal papillae of the genus Cosmocercoides.2. The existing species of the genus Cosmocerca Diesing, 1861 are listed and briefly described.

Active urea transport by the skin of Bufo viridis: amiloride- and phloretin-sensitive transport sites

1988 ◽  
Vol 255 (3) ◽  
pp. F429-F433 ◽  
Author(s):  
J. Rapoport ◽  
A. Abuful ◽  
C. Chaimovitz ◽  
Z. Noeh ◽  
R. M. Hays
Keyword(s):  
External Medium ◽  
Ringer Solution ◽  
Bufo Marinus ◽  
Urea Transport ◽  
Maximal Inhibition ◽  
Experimental Conditions ◽  
Bufo Viridis ◽  
Green Toad ◽  
Dose Response Study ◽  
Toad Bufo

Urea is actively transported inwardly (Ji) across the skin of the green toad Bufo viridis. Ji is markedly enhanced in toads adapted to hypertonic saline. We studied urea transport across the skin of Bufo viridis under a variety of experimental conditions, including treatment with amiloride and phloretin, agents that inhibit urea permeability in the bladder of Bufo marinus. Amiloride (10(-4) M) significantly inhibited Ji in both adapted and unadapted animals and was unaffected by removal of sodium from the external medium. Phloretin (10(-4) M) significantly inhibited Ji in adapted animals by 23–46%; there was also a reduction in Ji in unadapted toads at 10(-4) and 5 x 10(-4) M phloretin. A dose-response study revealed that the concentration of phloretin causing half-maximal inhibition (K1/2) was 5 x 10(-4) M for adapted animals. Ji was unaffected by the substitution of sucrose for Ringer solution or by ouabain. We conclude 1) the process of adaptation appears to involve an increase in the number of amiloride- and phloretin-inhibitable urea transport sites in the skin, with a possible increase in the affinity of the sites for phloretin; 2) the adapted skin resembles the Bufo marinus urinary bladder with respect to amiloride and phloretin-inhibitable sites; 3) we confirm earlier observations that Ji is independent of sodium transport.

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