6. PROPERTIES OF FISH HEMOGLOBINS
239
2. ELASMOBRANCHS
The early studics by McCutcheon (1947) indicated that the hemoglobins of three species of shark possessed higher oxygen affinities
( P,o ==: 7 mm) than found for six species of ray (P,, 13-15 mm). The
oxygen equilibria were not quite hyperbolic: n c 1.5-1.6 for the ray
hemoglobins and 1.2-1.3 for the sharks. These measurements at 25.S°C,
pH 7.4, and AN30 phosphate were made on very dilute solutions of hemoglobin; thus, their relationship to in uiuo or intraerythrocyte function
cannot be evaluated.
More recently, hlanwell (1958a, 1963a) has compared the ozygen
equilibria of erythrocyte suspensions and hemoglobin solutions from
the dogfish, Squalus suckleyi. He found that hemoglobin solutions (concentration, 1.5-2.0%) mirrored the properties of the red cell suspensions.
He found that no significant difference exists between the oxygen
equilibria of fresh, buffered hemolyzates, of crystallized, dialyzed preparations, or of rcd cell suspensions. Suspension of the red cells in either
0.5 or 1.0 M urea was without effect on the oxygen equilibrium. The
urea present in dogfish blood is therefore unlikely to have any direct
effect on oxygen transport. These facts do not suggest the presence of
aLiy intracellular modifier of oxygen transport. For the adult pigment,
n = 1 and the Bohr effect is low ( r = 0.34). The fetal pigment possessed
a higher oxygen affinity both in cells and in solution than did the adult
hemoglobin. This was shown to depend on the presence of a unique
fetal hemoglobin. Tryptic peptide patterns showed the presence of two
peptides absent in patterns from the adult. The fetal hemoglobin occurs
during most of the 22-23-month gestation period.
The absence of significant differences between cell and solution is
surprising. If the Bohr effect were really zero then the apparent equality
of the oxygen affinity inside and outside the cell would be understandable, but Manwell's data indicate that the Bohr effect is not zero. Therefore it is necessary to suppose that some difference between the oxygen
affinity of red cells and hemoglobin solutions must exist at every pH
except at the isoelectric point because of the Donnan equilibrium. However, recent experiments by Lenfant and Johansen (1966) failed to show
any effect of CO, or pH on the oxygen equilibrium of intact blood
from the same species.
Albers and Pleschka (1967) failed to find any significant Haldane
effect (effect of oxygen saturation on CO, content of blood) in studies
of blood from three elasmobranchs ( Scyliorhinus stellark, Torpedo
ocellata, and Mustelus mustelus). Since the Haldane effect is but the
239
2. ELASMOBRANCHS
The early studics by McCutcheon (1947) indicated that the hemoglobins of three species of shark possessed higher oxygen affinities
( P,o ==: 7 mm) than found for six species of ray (P,, 13-15 mm). The
oxygen equilibria were not quite hyperbolic: n c 1.5-1.6 for the ray
hemoglobins and 1.2-1.3 for the sharks. These measurements at 25.S°C,
pH 7.4, and AN30 phosphate were made on very dilute solutions of hemoglobin; thus, their relationship to in uiuo or intraerythrocyte function
cannot be evaluated.
More recently, hlanwell (1958a, 1963a) has compared the ozygen
equilibria of erythrocyte suspensions and hemoglobin solutions from
the dogfish, Squalus suckleyi. He found that hemoglobin solutions (concentration, 1.5-2.0%) mirrored the properties of the red cell suspensions.
He found that no significant difference exists between the oxygen
equilibria of fresh, buffered hemolyzates, of crystallized, dialyzed preparations, or of rcd cell suspensions. Suspension of the red cells in either
0.5 or 1.0 M urea was without effect on the oxygen equilibrium. The
urea present in dogfish blood is therefore unlikely to have any direct
effect on oxygen transport. These facts do not suggest the presence of
aLiy intracellular modifier of oxygen transport. For the adult pigment,
n = 1 and the Bohr effect is low ( r = 0.34). The fetal pigment possessed
a higher oxygen affinity both in cells and in solution than did the adult
hemoglobin. This was shown to depend on the presence of a unique
fetal hemoglobin. Tryptic peptide patterns showed the presence of two
peptides absent in patterns from the adult. The fetal hemoglobin occurs
during most of the 22-23-month gestation period.
The absence of significant differences between cell and solution is
surprising. If the Bohr effect were really zero then the apparent equality
of the oxygen affinity inside and outside the cell would be understandable, but Manwell's data indicate that the Bohr effect is not zero. Therefore it is necessary to suppose that some difference between the oxygen
affinity of red cells and hemoglobin solutions must exist at every pH
except at the isoelectric point because of the Donnan equilibrium. However, recent experiments by Lenfant and Johansen (1966) failed to show
any effect of CO, or pH on the oxygen equilibrium of intact blood
from the same species.
Albers and Pleschka (1967) failed to find any significant Haldane
effect (effect of oxygen saturation on CO, content of blood) in studies
of blood from three elasmobranchs ( Scyliorhinus stellark, Torpedo
ocellata, and Mustelus mustelus). Since the Haldane effect is but the