204
C. ALBERS
with those of indicator methods or with methods applying the Henderson-Hasselbalch equation for tissue CO,.
An interesting approach to the intracellular pH was made by Waddell
and Butler (1959); it is based on the weak acid DMO which can permeate the cell membrane only as an undissociated acid. Thus, extracellular and intracellular concentrations of the undissociated acid are
equal. If the total concentration of DMO is determined in the extracellular fluid (plasma) as well as in the intracellular fluid, the undissociated moiety can be calculated by means of the pK’ of DMO and the
plasma pH. In the next step of the calculation the dissociated moiety
is obtained by simple subtraction of the undissociated fraction from the
total concentration. Finally, the intracellular pH is obtained by again
applying the Henderson-Hasselbalch equation. Using the glass electrode
as well as the DMO method, Robin (1961) determined the pH of the
pericardial fluid of the dogfish (Squalus acanthias) and found good
agreement between both methods. The average pH of the pericardial
fluid was about 5.6. Robin et al. (1964) determined the intracellular
pH with the DMO method in the same species and reported 7.41 as
average for the brain and 6.95 for the muscle.
V. CONTROLLING MECHANISMS OF THE
ACID-BASE BALANCE
It is not the aim of this section to describe in detail the operation
of the controlling mechanisms of the acid-base balance. The reader is
referred to the pertinent chapters of these volumes. Instead we shall
briefly summarize the basic principles of the regulatory mechanisms involved as can be deduced from the previous sections. All quantities used
in the many equations of this chapter can be divided into three groups:
(1) The first group consists of pure physicochemical constants, such
as the ionic product of water Kw, the dissociation constants K of the
participating acids and buffer substances, the solubility of C 0 2 , etc.
These constants depend on temperature and ionic strength. The organism
has to cope with these quantities which are completely independent of
biological regulation.
( 2 ) The second group is made up of the concentrations of the substances involved in the acid-base balance except the physically dissolved
CO, (and the bicarbonate). Among these quantities are thc various
electrolytes, the plasma proteins, the hemoglobin, and other buffer
substances. This group is subjected to regulatory mechanisms of several
C. ALBERS
with those of indicator methods or with methods applying the Henderson-Hasselbalch equation for tissue CO,.
An interesting approach to the intracellular pH was made by Waddell
and Butler (1959); it is based on the weak acid DMO which can permeate the cell membrane only as an undissociated acid. Thus, extracellular and intracellular concentrations of the undissociated acid are
equal. If the total concentration of DMO is determined in the extracellular fluid (plasma) as well as in the intracellular fluid, the undissociated moiety can be calculated by means of the pK’ of DMO and the
plasma pH. In the next step of the calculation the dissociated moiety
is obtained by simple subtraction of the undissociated fraction from the
total concentration. Finally, the intracellular pH is obtained by again
applying the Henderson-Hasselbalch equation. Using the glass electrode
as well as the DMO method, Robin (1961) determined the pH of the
pericardial fluid of the dogfish (Squalus acanthias) and found good
agreement between both methods. The average pH of the pericardial
fluid was about 5.6. Robin et al. (1964) determined the intracellular
pH with the DMO method in the same species and reported 7.41 as
average for the brain and 6.95 for the muscle.
V. CONTROLLING MECHANISMS OF THE
ACID-BASE BALANCE
It is not the aim of this section to describe in detail the operation
of the controlling mechanisms of the acid-base balance. The reader is
referred to the pertinent chapters of these volumes. Instead we shall
briefly summarize the basic principles of the regulatory mechanisms involved as can be deduced from the previous sections. All quantities used
in the many equations of this chapter can be divided into three groups:
(1) The first group consists of pure physicochemical constants, such
as the ionic product of water Kw, the dissociation constants K of the
participating acids and buffer substances, the solubility of C 0 2 , etc.
These constants depend on temperature and ionic strength. The organism
has to cope with these quantities which are completely independent of
biological regulation.
( 2 ) The second group is made up of the concentrations of the substances involved in the acid-base balance except the physically dissolved
CO, (and the bicarbonate). Among these quantities are thc various
electrolytes, the plasma proteins, the hemoglobin, and other buffer
substances. This group is subjected to regulatory mechanisms of several