Thermodynamic considerations of arteriovenous gradients of hydrogen ion concentration and carbon dioxide tension

2000 ◽  
Vol 37 (2) ◽  
pp. 114-118 ◽  
Author(s):  
Emmanuel T Rakitzis
Keyword(s):  
Heart Failure ◽  
Carbon Dioxide ◽  
Congestive Heart Failure ◽  
Free Energy ◽  
Carbon Dioxide Tension ◽  
Hydrogen Ion ◽  
Free Energy Change ◽  
Ion Concentration ◽  
Energy Change ◽  
Hydrogen Ion Concentration

It is shown that, in a multicompartmental homeostatic system, the extent of interaction between any two compartments can be assessed by determination of the difference in free energy change of one particular reaction, or a series of coupled reactions, operative in both of the compartments under consideration. Hydrogen ion concentration and carbon dioxide tension have been used to determine free energy change difference relationships between the venous and arterial compartments (- G(a-v)) of the circulatory system. Data from the literature (from two studies of congestive heart failure and one study of experimentally induced cardiac arrest) are used to calculate - G(a-v). It was found that in control subjects - G(a-v) is close to zero, whereas in congestive heart failure or cardiac arrest, the value rises to 150 calmol-1 or more, whereas in blood, the approach towards equilibrium between hydrogen and bicarbonate ions and dissolved carbon dioxide (aqueous CO2) is known to be only moderately rapid. It is concluded that, in the system under study, and with respect to the reaction H+ + HCO3- = CO2 + H2O, a high value for the free energy change difference between the two compartments (high - G(a-v)) must be due to an insufficient blood circulation rate. Accordingly, - G(a-v) is probably a quantitative measure of cardiac insufficiency.

scholarly journals CHANGES IN CARBON DIOXIDE TENSION AND HYDROGEN ION CONCENTRATION OF THE BLOOD FOLLOWING MULTIPLE PULMONARY EMBOLISM

1927 ◽  
Vol 45 (4) ◽  
pp. 633-641 ◽  
Author(s):  
Carl A. L. Binger ◽  
Richmond L. Moore
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Tension ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Characteristic Type ◽  
Pulmonary Capillaries ◽  
Partial Pressure Of Co2 ◽  
Shallow Breathing ◽  
Impaired Pulmonary Function

1. The production of multiple emboli of the pulmonary capillaries and arterioles results in rapid and shallow breathing which may be associated with anoxemia, but is not dependent for its occurrence upon anoxemia. 2. Similarly there may occur an increase in the partial pressure of CO2 in the blood as well as an increase in hydrogen ion concentration. 3. These changes must be regarded as the result of the impaired pulmonary function. 4. They are not, however, the cause of the rapid and shallow respirations, since the abnormal type of breathing may occur without the attendant blood changes. 5. The characteristic type of response to increase in CO2 tension is an increased rather than a decreased depth of respiration.

scholarly journals Cerebral Blood Flow Response to Increases in Arterial CO2 Tension during Alfentanil Anesthesia in the Rabbit

1992 ◽  
Vol 12 (3) ◽  
pp. 529-532 ◽  
Author(s):  
G. L. Ludbrook ◽  
S. C. Helps ◽  
D. F. Gorman
Keyword(s):  
Blood Flow ◽  
Carbon Dioxide Tension ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Cerebral Function ◽  
Cortical Function ◽  
Hydrogen Ion Concentration ◽  
Flow Response ◽  
The Stability ◽  
The Right

The stability of cerebral function and blood flow (CBF), and the CBF response to changes in arterial carbon dioxide tension (CBF reactivity) during alfentanil anesthesia were examined in rabbits. This model was first shown to provide stable anesthesia, cortical function, and CBF for 4 h. CBF increased significantly to 159% [of baseline] in the left hemisphere and to 167% in the right within 5 min of an exposure to 5% CO2 ( p = 0.009 on the left and p = 0.003 on the right), but then decreased to 123% on the left and to 137% on the right (not significantly different from baseline, p = 0.11 on the left and p = 0.07 on the right) while PaCO2 was still rising. Steady state reactivity levels (0.8 ml 100 g−1/min−1/mm Hg−1 CO2 on the left and 0.65 ml 100 g−1/min−1/mm Hg−1 CO2 on the right) were consistent with previous work and were reached at 20 min. These results suggest that mechanisms other than perivascular hydrogen ion concentration mediate the CBF response to changes in arterial CO2 tension during alfentanil anesthesia.

scholarly journals REGULATION OF THE HYDROGEN ION CONCENTRATION AND ITS RELATION TO METABOLISM AND RESPIRATION IN THE STARFISH

1926 ◽  
Vol 10 (2) ◽  
pp. 345-358 ◽  
Author(s):  
Laurence Irving
Keyword(s):  
Carbon Dioxide ◽  
Sea Water ◽  
Carbon Dioxide Production ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Coelomic Fluid ◽  
Vital Function ◽  
Hydrogen Ion Concentration ◽  
Optimum Ph ◽  
Patiria Miniata

The normal reaction of the cœlomic fluid in Patiria miniata and Asterias ochraceus is pH 7.6, and of the cæca, 6.7, compared with sea water at 8.3, all without salt error correction. A medium at pH 6.7–7.0 is optimum for the cæca for ciliary survival and digestion of protein, and is maintained by carbon dioxide production. The optimum pH found for carbon dioxide production is a true one for the effect of hydrogen ion concentration on the tissue. It does not represent an elimination gradient for carbon dioxide. Because the normal excised cæca maintain a definite hydrogen ion concentration and change their internal environment toward that as an optimum during life, there exists a regulatory process which is an important vital function.

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