scholarly journals Nonequilibrium Thermodynamic Analysis of the Coupling between Active Sodium Transport and Oxygen Consumption

1974 ◽  
Vol 64 (3) ◽  
pp. 372-391 ◽  
Author(s):  
G. Danisi ◽  
F. Lacaz Vieira
Keyword(s):  
Oxygen Consumption ◽  
Sodium Transport ◽  
Chemical Potential ◽  
Nonequilibrium Thermodynamic ◽  
Potential Difference ◽  
Stoichiometric Ratio ◽  
Active Sodium ◽  
Na Transport ◽  
Chemical Potential Difference ◽  
Active Sodium Transport

Sodium transport and oxygen consumption have been simultaneously studied in the short-circuited toad skin. A constant stoichiometric ratio was observed in each skin under control condition (NaCl-Ringer's solution bathing both sides of the skin) and after block of sodium transport by ouabain. During alterations of sodium transport by removal and addition of K to the internal solution the stoichiometric ratio is constant although having a value higher than that observed in other untreated skins. The coupling between active sodium transport and oxygen consumption was studied after a theoretical nonequilibrium thermodynamic model. Studies were made of the influence of Na chemical potential difference across the skin on the rates of Na transport and oxygen consumption. A linear relationship was observed between the rates of Na transport and oxygen consumption and the Na chemical potential difference. Assuming the Onsager relationship to be valid, the three phenomenological coefficients which describe the system were evaluated. Transient increases in the rate of sodium transport and oxygen consumption were observed after a transitory block of sodium transport by removal of Na from the external solution. Cyanide blocks completely the rate of oxygen consumption in less than 2 min and the short-circuit current measured after that time decays exponentially with time, suggesting a depletion of ATP from a single compartment.

Active sodium transport in toad bladder despite removal of serosal potassium

1965 ◽  
Vol 208 (2) ◽  
pp. 401-406 ◽  
Author(s):  
Alvin Essig
Keyword(s):  
Sodium Transport ◽  
Chemical Potential ◽  
Potential Gradient ◽  
Ringer Solution ◽  
Active Sodium ◽  
Chemical Potential Gradient ◽  
Control Value ◽  
Active Sodium Transport ◽  
Solution Bathing ◽  
Determining Factor

Previous studies have demonstrated that removal of potassium from sodium-Ringer solution bathing the serosal surface of the toad badder depressed net sodium transport to some 5% of control value, whereas with choline-Ringer solution as serosal medium removal of serosal potassium depressed net sodium transport only to some 55% of control value. Although transport is down a chemical potential gradient in the latter situation, it appears to be an active process, for it is depressed by anaerobiosis, and persists against an electrochemical potential gradient. The data suggest that the concentration of potassium at the serosal aspect of the sodium pump is not in itself the rate-determining factor for active sodium transport following removal of serosal potassium.

Aldosterone response in the turtle bladder is associated with an increase in ATP

1983 ◽  
Vol 245 (4) ◽  
pp. F512-F514
Author(s):  
N. Cortas ◽  
E. Abras ◽  
M. Walser
Keyword(s):  
Perchloric Acid ◽  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Potential Difference ◽  
Freshwater Turtles ◽  
Active Sodium ◽  
Active Sodium Transport ◽  
Turtle Bladder

Urinary bladders from freshwater turtles, mounted as sacs, were stripped of their serosa and submucosa. This did not alter conductance. They were maintained in open circuit except for brief observation of short-circuit current (SCC) every 15 min. Potential difference (PD) averaged 68 +/- 14 mV and SCC 485 +/- 100 microA. Acetazolamide 10(-3) M increased SCC by 46 +/- 27 microA. Aldosterone 10(-7) M following acetazolamide resulted in a rise in SCC that began at about 75 min and reached a plateau between 3 and 5 h. SCC rose 127 +/- 15% compared with control bladder halves. ATP measured in perchloric acid extracts 5 h after addition of aldosterone increased by 33% (P less than 0.01) and (ATP)/(ADP) X (Pi) by 81% (P less than 0.01). These results support the view that the stimulatory effects of aldosterone on active sodium transport involve an increase in ATP and (ATP)/(ADP) X (Pi).

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