Περίληψη:
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
(-Delta Delta 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 -Delta
Delta G((a-v)). It was found that in control subjects -Delta Delta
G((a-v)) is close to zero, whereas in congestive heart failure or
cardiac arrest, the value rises to 150 cal mol(-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 thigh
-Delta Delta G((a-v))) must be due to an insufficient blood circulation
rate. Accordingly, -Delta Delta G((a-v)) is probably a quantitative
measure of cardiac insufficiency.
