280
D. J. RANDALL
veloped. Although there is no adequate method for the cxtensive analysis
of the interaction of several parameters, a few investigators have attempted to analyze certain aspects of gas exchange in fish.
B. Transfer Factor
The transfer factor of the gills for a particular gas is a measure of
the ability of the gills to transfer that gas per unit gradient. The transfer
factor of the gills for oxygen To? is defined as
v o , (oxygen uptake)
AFo2 (mean oxygen gradient across gill epithelium)
To2 =
Randall et al. (1967) calculated the mean gradient using the following equation
Po2 = ~ ( P I o ,
+ PEO*) - %(PaoZ + Pvo,)
where PI^. is the inspired oxygen level, P E ~ *
the expired oxygen level,
Paos the arterial oxygen tension, and Pvo, the venous oxygen level. Piiper
and Baumgarten-Schumann ( 1968a), criticizing this method on the
grounds that the mean gradient was affected by the slope of the blood
oxygen dissociation curve, used a modified Bohr integration technique
to determine To,. Uptake was divided into a series of steps, and then
the To? for each step calculated. The mean partial pressures for each
step were .obtained using an oxygen dissociation curve. The total To? value
was obtained by summation of the individual To, values for each of the
steps of Vo2. They found that the differences were small in the calculated
values of To, and Tcos, obtained for dogfish using the method of Randall
et al. (1967) and the Bohr integration technique.
The transfer factor of the gills for oxygen ( T O 2 ) in the resting trout
is 0.0056 ml/min/mm Hg/kg, increasing by a factor of five during moderate swimming (Randall et al., 1967). The ratio of Tco, (the transfer
factor of the gills for carbon dioxide) to To? is about 20:l decreasing
to 14: 1 during activity (Stevens, 196813). That is, the transfer factor of
the gills for oxygcn increases more than the transfer factor for CO,
during swimming in the trout. Thc reported To, for the dogfish is 0.0080
ml/min/mm Hglkg ( Piiper and Baumgarten-Schumann, 1968a), a value
very similar to that for the resting trout. The ratio of Tco2 to To, is
56: 1 in the dogfish (Piiper and Baumgarten-Schumann, 1968a).
The transfer factor may be altered by changing the functional area
of the gills or diffusion distance between blood and water by changing
the pattern of blood or water flow over the respiratory surface. The
D. J. RANDALL
veloped. Although there is no adequate method for the cxtensive analysis
of the interaction of several parameters, a few investigators have attempted to analyze certain aspects of gas exchange in fish.
B. Transfer Factor
The transfer factor of the gills for a particular gas is a measure of
the ability of the gills to transfer that gas per unit gradient. The transfer
factor of the gills for oxygen To? is defined as
v o , (oxygen uptake)
AFo2 (mean oxygen gradient across gill epithelium)
To2 =
Randall et al. (1967) calculated the mean gradient using the following equation
Po2 = ~ ( P I o ,
+ PEO*) - %(PaoZ + Pvo,)
where PI^. is the inspired oxygen level, P E ~ *
the expired oxygen level,
Paos the arterial oxygen tension, and Pvo, the venous oxygen level. Piiper
and Baumgarten-Schumann ( 1968a), criticizing this method on the
grounds that the mean gradient was affected by the slope of the blood
oxygen dissociation curve, used a modified Bohr integration technique
to determine To,. Uptake was divided into a series of steps, and then
the To? for each step calculated. The mean partial pressures for each
step were .obtained using an oxygen dissociation curve. The total To? value
was obtained by summation of the individual To, values for each of the
steps of Vo2. They found that the differences were small in the calculated
values of To, and Tcos, obtained for dogfish using the method of Randall
et al. (1967) and the Bohr integration technique.
The transfer factor of the gills for oxygen ( T O 2 ) in the resting trout
is 0.0056 ml/min/mm Hg/kg, increasing by a factor of five during moderate swimming (Randall et al., 1967). The ratio of Tco, (the transfer
factor of the gills for carbon dioxide) to To? is about 20:l decreasing
to 14: 1 during activity (Stevens, 196813). That is, the transfer factor of
the gills for oxygcn increases more than the transfer factor for CO,
during swimming in the trout. Thc reported To, for the dogfish is 0.0080
ml/min/mm Hglkg ( Piiper and Baumgarten-Schumann, 1968a), a value
very similar to that for the resting trout. The ratio of Tco2 to To, is
56: 1 in the dogfish (Piiper and Baumgarten-Schumann, 1968a).
The transfer factor may be altered by changing the functional area
of the gills or diffusion distance between blood and water by changing
the pattern of blood or water flow over the respiratory surface. The