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.

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.

scholarly journals Age and Growth of the Green Toad, Bufo viridis (Laurenti, 1768) from an Island and a Mainland Population in Giresun, Turkey

2011 ◽  
Vol 10 (11) ◽  
pp. 1469-1472 ◽  
Author(s):  
Bilal Kutrup ◽  
Emel Cakir ◽  
Zeliha Colak ◽  
Ufuk Bulbul ◽  
Handan Karaoglu
Keyword(s):  
Age And Growth ◽  
Mainland Population ◽  
Bufo Viridis ◽  
Green Toad ◽  
Toad Bufo

scholarly journals Features of learning in toads Bufo viridis during behavior that requires taking into account the limits of their own bodies

2018 ◽  
Vol 11 (4) ◽  
pp. 5-16 ◽  
Author(s):  
I.A. Khvatov ◽  
R.V. Zhelankin
Keyword(s):  
Body Schema ◽  
Experimental Setup ◽  
Bufo Viridis ◽  
Green Toad ◽  
External Objects ◽  
Natural Boundaries ◽  
Tactile Sensations ◽  
Toad Bufo ◽  
Extraneous Object

The goal of this work was to study the ability of the green toad Bufo viridis to form skills based on tactile sensations arising in the process of interaction between animal’s body and external objects. During the experiment we varied the proportions of the holes in the experimental setup, through which the animal penetrated, and the limits of the animal bodies by attaching blankets to their body with an extraneous object. It was found that toads can to take into account the natural limits of their own body when interacting with external objects, and also transfer this experience in a situation where the proportions of the holes in the experiment setup was varied. When the limits of the toad body were urgently changed so that these changes prevent the animals from penetration into certain types of holes, these animals did not learn to take into account the fact that the holes previously permeable to the natural limits of their bodies became impenetrable after increasing these limits. We state that these data indicate that the toads even before the experiment began had experience of taking into account the natural boundaries of their bodies. But toads are not able to modify their body schema, when the limits of their bodies are urgently increased.

scholarly journals Growth and development of the green toad (Bufo viridis) from the water bodies of the oil producing regions of Kazakhstan

2018 ◽  
Vol 2 (55) ◽  
pp. 111-120
Author(s):  
L.R. Sutuyeva ◽  
◽  
T.M. Shalakhmetova ◽  
V.L. Trudeau ◽  
S.Zh. Kolumbayeva ◽  
...  
Keyword(s):  
Growth And Development ◽  
Water Bodies ◽  
Bufo Viridis ◽  
Green Toad ◽  
Toad Bufo

scholarly journals Metabolic costs induced by lactate in the toad Bufo marinus: new mechanism behind oxygen debt?

2003 ◽  
Vol 94 (3) ◽  
pp. 1177-1185 ◽  
Author(s):  
Ilka Pinz ◽  
Hans-O. Pörtner
Keyword(s):  
Metabolic Rate ◽  
Energy Demand ◽  
Isolated Hepatocytes ◽  
Ringer Solution ◽  
Bufo Marinus ◽  
Proton Exchange ◽  
Plasma Catecholamine ◽  
Proton Symport ◽  
Toad Bufo

The mechanism of an increase in metabolic rate induced by lactate was investigated in the toad Bufo marinus. Oxygen consumption (V˙o 2) was analyzed in fully aerobic animals under hypoxic conditions (7% O2 in air), accompanied by measurements of catecholamines in the plasma, and was measured in isolated hepatocytes in vitro under normoxia by using specific inhibitors of lactate proton symport [α-cyano-4-hydroxycinnamate (CHC)] and sodium proton exchange (EIPA). The rise in metabolic rate in vivo can be elicited by infusions of hyperosmotic (previous findings) or isosmotic sodium lactate solutions (this study). Despite previous findings of reduced metabolic stimulation under the effect of adrenergic blockers, the increase inV˙o 2 in vivo was not associated with elevated plasma catecholamine levels, suggesting local release and effect. In addition to the possible in vivo effect via catecholamines, lactate induced a rise in V˙o 2 of isolated hepatocytes, depending on the concentration present in a weakly buffered Ringer solution at pH 7.0. No increase was found at higher pH values (7.4 or 7.8) or in HEPES-buffered Ringer solution. Inhibition of the Lac−-H+ transporter with α-CHC or of the Na+/H+ exchanger with EIPA prevented the increase in metabolic rate. We conclude that increasedV˙o 2 at an elevated systemic lactate level may involve catecholamine action, but it is also caused by an increased energy demand of cellular acid-base regulation via stimulation of Na+/H+ exchange and thereby Na+-K+-ATPase. The effect depends on entry of lactic acid into the cells via lactate proton symport, which is likely favored by low cellular surface pH. We suggest that these energetic costs should also be considered in other physiological phenomena, e.g., when lactate is present during excess, postexerciseV˙o 2.

In vitro cardiotoxicity and mechanism of action of the Egyptian green toad Bufo viridis skin secretions

2010 ◽  
Vol 24 (2) ◽  
pp. 480-485 ◽  
Author(s):  
Mohamed A. Abdel-Rahman ◽  
Sherifa Hamid Ahmed ◽  
Zohour I. Nabil
Keyword(s):  
Mechanism Of Action ◽  
Bufo Viridis ◽  
Green Toad ◽  
Skin Secretions ◽  
Toad Bufo
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