282
D. J. RANDALL
of oxygen removal from the water. Comparison of the effectiveness of
gas transfer between fish and man (Randall et al., 1967; Piiper and
Baumgarten-Schumann, 1968a) indicate that the CO, uptake by and 0,
removal from the medium and 0, uptake by the blood is similar in man
and fish.
D. Capacity Rate Ratio
Hughes and Shelton (1962) compared the capacity rates of watcr
( V(j.atco,) and blood ( Qc.abo,) and discussed the relevance of a changing capacity rate ratio of water and blood on gas exchange across the
gills. (Q(; = gill blood flow; V G = gill water flow; aho, = oxygen content
of blood per nim Hg; awo2 = oxygen solubility coefficient in water.) The
oxygen content of blood is not linearly related to Po? but changes in
proportion to the slope of the oxygen dissociation curve. The shape of
the dissociation curve is affectcd by Pco2, pH, and temperature of the
blood. The solubility of oxygen in water is affected by temperature and
ionic content of thc water. The value of using capacity rate ratio in an
analysis of gas exchange in fish is limited by the large number of variables
that must be measured before capacity rate ratio can be determined.
The capacity rate ratio of water to blood in the resting and active trout
is about 5 (Randall et al., 1967).
E. Ventilation-Perfusion Ratio
Although the effects of changes in the ventilation-perfusion ratio
on gas exchange have been extensively studied in mammals, very little
attention has been paid to the effects of variations in this ratio in fish.
The V,/Q ratio is extremely variable in fish and ranges from 1 O : l in
the carp and dogfish (Piiper and Schumann, 1967; Garey, 1967) to
8 O : l in the trout (Stevens and Randall, 1967b). The ratio increases in
the trout during hypoxia (Holeton and Randall, 196713). There has
been no extensive analysis to date of the effect of changing Vci/Q ratios
on gas exchange in fish.
Although there is little concrete data on changes in the ratio of blood
to water flow at the gills, there are a number of observations on the
relationship between heartbeat and breathing movements in fish ( Randall, 1968). The heart beats during a particular phase of the breathing
cycle in many fish (Hanson, 1967; Satchell, 1960), and there may be a
1:1, 1:2, or 1:3 ratio between heart and breathing rates. In the trout,
D. J. RANDALL
of oxygen removal from the water. Comparison of the effectiveness of
gas transfer between fish and man (Randall et al., 1967; Piiper and
Baumgarten-Schumann, 1968a) indicate that the CO, uptake by and 0,
removal from the medium and 0, uptake by the blood is similar in man
and fish.
D. Capacity Rate Ratio
Hughes and Shelton (1962) compared the capacity rates of watcr
( V(j.atco,) and blood ( Qc.abo,) and discussed the relevance of a changing capacity rate ratio of water and blood on gas exchange across the
gills. (Q(; = gill blood flow; V G = gill water flow; aho, = oxygen content
of blood per nim Hg; awo2 = oxygen solubility coefficient in water.) The
oxygen content of blood is not linearly related to Po? but changes in
proportion to the slope of the oxygen dissociation curve. The shape of
the dissociation curve is affectcd by Pco2, pH, and temperature of the
blood. The solubility of oxygen in water is affected by temperature and
ionic content of thc water. The value of using capacity rate ratio in an
analysis of gas exchange in fish is limited by the large number of variables
that must be measured before capacity rate ratio can be determined.
The capacity rate ratio of water to blood in the resting and active trout
is about 5 (Randall et al., 1967).
E. Ventilation-Perfusion Ratio
Although the effects of changes in the ventilation-perfusion ratio
on gas exchange have been extensively studied in mammals, very little
attention has been paid to the effects of variations in this ratio in fish.
The V,/Q ratio is extremely variable in fish and ranges from 1 O : l in
the carp and dogfish (Piiper and Schumann, 1967; Garey, 1967) to
8 O : l in the trout (Stevens and Randall, 1967b). The ratio increases in
the trout during hypoxia (Holeton and Randall, 196713). There has
been no extensive analysis to date of the effect of changing Vci/Q ratios
on gas exchange in fish.
Although there is little concrete data on changes in the ratio of blood
to water flow at the gills, there are a number of observations on the
relationship between heartbeat and breathing movements in fish ( Randall, 1968). The heart beats during a particular phase of the breathing
cycle in many fish (Hanson, 1967; Satchell, 1960), and there may be a
1:1, 1:2, or 1:3 ratio between heart and breathing rates. In the trout,