236
AUSTEN RIGGS
described in terms either of metabolic requirements or of environmental
oxygen pressures, these factors cannot be separated from one another.
The most active fish must inhabit a high oxygen environment; they
could not otherwise obtain sufficient oxygen for their activity.
Air-breathing fish, of course, can bypass their low oxygen aqueous
environment.
These conclusions concerning adaptation are largely based on studies
of blood by many individuals over the last five decades; much of the
data has been reviewed by Manwell (1960) and by Prosser and Brown
(1961). For the most part, the intrinsic properties of hemoglobin are
not adequately distinguished from the modified properties in the red
blood cell. Krogh and Leitch (1919), in the first comparative study of
fish bloods, clearly anticipated the possibility that fish red cells might
contain allosteric substances which could control the oxygen transport
properties:
We believe that the adaptation of fish blood must be brought about by some
substance or substances present along with the haemoglobin within the corpuscles,
and we wish to point out the general significance of the haemoglobin being enclosed
in corpuscles surrounded by semipermeable membranes. By this arrangement just
that chemical environment can be secured which is most suitable for the respiratory
function of the haemoglobin in that particular organism, while at the same time the
chemical composition of the blood plasma can be adapted, as it must needs be, to
the general requirements of the body cells . . . the possession of semipermeable
red corpuscles is therefore a necessary condition for utilizing to the full wonderful
respiratory properties of the haemoglobin.
Although this was written fifty years ago, we still know little about
these relationships. In the following discussion an attempt will be made
to distinguish between what are presumed to be properties of hemoglobin
and those of blood or red cell suspensions. This distinction has often
not been made in the physiological literature which is rife with descriptions of “hemoglobin-oxygen dissociation curves” when whole blood is
really being described.
1. CYCLOSTOMES
From the standpoint of cooperativity of 0, binding, lamprey hemoglobin is one of the most instructive because subunit aggregation is
functionally linked to deoxygenation. The first measurements ( Wald and
Riggs, 1951) on hemoglobin from Petromyxon marinus showed that n
was usually close to unity, but it was sometimes significantly higher.
Because the molecule was then believed always to be monomeric, with
only a single heme, values higher than 1.0 were attributed to experimental errors. Briehl (1963), Love and Rumen (1963), and Rumen and
AUSTEN RIGGS
described in terms either of metabolic requirements or of environmental
oxygen pressures, these factors cannot be separated from one another.
The most active fish must inhabit a high oxygen environment; they
could not otherwise obtain sufficient oxygen for their activity.
Air-breathing fish, of course, can bypass their low oxygen aqueous
environment.
These conclusions concerning adaptation are largely based on studies
of blood by many individuals over the last five decades; much of the
data has been reviewed by Manwell (1960) and by Prosser and Brown
(1961). For the most part, the intrinsic properties of hemoglobin are
not adequately distinguished from the modified properties in the red
blood cell. Krogh and Leitch (1919), in the first comparative study of
fish bloods, clearly anticipated the possibility that fish red cells might
contain allosteric substances which could control the oxygen transport
properties:
We believe that the adaptation of fish blood must be brought about by some
substance or substances present along with the haemoglobin within the corpuscles,
and we wish to point out the general significance of the haemoglobin being enclosed
in corpuscles surrounded by semipermeable membranes. By this arrangement just
that chemical environment can be secured which is most suitable for the respiratory
function of the haemoglobin in that particular organism, while at the same time the
chemical composition of the blood plasma can be adapted, as it must needs be, to
the general requirements of the body cells . . . the possession of semipermeable
red corpuscles is therefore a necessary condition for utilizing to the full wonderful
respiratory properties of the haemoglobin.
Although this was written fifty years ago, we still know little about
these relationships. In the following discussion an attempt will be made
to distinguish between what are presumed to be properties of hemoglobin
and those of blood or red cell suspensions. This distinction has often
not been made in the physiological literature which is rife with descriptions of “hemoglobin-oxygen dissociation curves” when whole blood is
really being described.
1. CYCLOSTOMES
From the standpoint of cooperativity of 0, binding, lamprey hemoglobin is one of the most instructive because subunit aggregation is
functionally linked to deoxygenation. The first measurements ( Wald and
Riggs, 1951) on hemoglobin from Petromyxon marinus showed that n
was usually close to unity, but it was sometimes significantly higher.
Because the molecule was then believed always to be monomeric, with
only a single heme, values higher than 1.0 were attributed to experimental errors. Briehl (1963), Love and Rumen (1963), and Rumen and