Gas Transport and Exchange

Magnitude of the Root effect in red blood cells and haemoglobin solutions of fishes: a tribute to August Krogh

“…A choroid rete mirabile of the eye and a swimbladder rete mirabile are absent in early ray‐finned fishes such as sturgeons (Berenbrink et al. 2005, Brauner & Berenbrink 2007) and the physiological role of a Root effect in species such as sturgeons and gars is enigmatic, given that a Root effect may impair full Hb O 2 loading in gill blood during general acidosis. However, higher specific buffer values of sturgeon Hbs, lower maximal Root effects and lower haemolysate pH values required for half‐maximal Root effects in these species may reduce the cost of possessing a Root effect considerably compared with typical teleosts (Berenbrink et al.…”

Magnitude of the Root effect in red blood cells and haemoglobin solutions of fishes: a tribute to August Krogh

“…A choroid rete mirabile of the eye and a swimbladder rete mirabile are absent in early ray‐finned fishes such as sturgeons (Berenbrink et al. 2005, Brauner & Berenbrink 2007) and the physiological role of a Root effect in species such as sturgeons and gars is enigmatic, given that a Root effect may impair full Hb O 2 loading in gill blood during general acidosis. However, higher specific buffer values of sturgeon Hbs, lower maximal Root effects and lower haemolysate pH values required for half‐maximal Root effects in these species may reduce the cost of possessing a Root effect considerably compared with typical teleosts (Berenbrink et al.…”

In vivored blood cell sickling and mechanism of recovery in whiting,Merlangius merlangus

“…The apparent cooperativity constants for low-pH-induced sickling suggest highly cooperative proton binding to Hb during the sickling process. In the absence of catecholamines, protons are usually passively distributed across the RBC membrane, with changes in plasma pH causing distinctly smaller changes in intracellular pH, as also seen in the close relative of whiting, the Atlantic cod (Berenbrink and Bridges, 1994a;Berenbrink and Bridges, 1994b) (for a review, see Brauner and Berenbrink, 2007). When sickling is more appropriately related to intracellular pH changes in the vicinity of Hb, even higher cooperativity constants can be calculated.…”

Regulation of erythrocyte function: Multiple evolutionary solutions for respiratory gas transport and its regulation in fish

“…1 The low O 2 availability of water is thought to have been an important selective force in the evolution of respiratory systems in fish. 10 Apart from mammals, all vertebrates have erythrocytes that are nucleated and contain other cell organelles, which may partly explain why many features of the regulation of erythrocyte function, important for the different environmental adaptations in fish, are not utilized in air-breathing mammals with their organelle-free erythrocytes. 5 Three major alternative solutions in the gas transport by erythrocytes have evolved in fish: that employed by agnathans, 6 that used by elasmobranchs, 7,8 and that found in teleosts.…”

“…As a result, the O 2 transport system of fish is the most versatile among vertebrates, [2][3][4] with the most extreme adaptation in fishes being the ability to breathe air which occurs in approximately 500 species. [10][11][12] This is an important point to consider when using teleost fishes such as zebrafish (Danio rerio) to study O 2 -dependent phenomena with a mammalian biomedical application: the zebrafish is a very hypoxia-tolerant tropical cyprinid. 9 The pattern employed by elasmobranchs may be the most representative of fish ancestors of the tetrapods and hence mammals.…”

“…Early studies on agnathan Hbs failed to see aggregation (and cooperativity), 56 because dilution favours monomerization. 60 Two significant properties of lamprey Hb within erythrocytes are the marked Bohr effect (with a Bohr coefficient of around −1, 56 which contrasts with a much lower mammalian value of around −0.5 61 ), and the reduction in the O 2 carrying capacity of the blood at air-saturated O 2 tensions at low pH, 56 a phenomenon that is more commonly associated with the blood of teleost fishes, 62 where it is referred to as the "Root effect" (for review see: 10,63 ). [57][58][59] A schematic depiction of aggregation-dependent O 2 affinity regulation is given in Figure 3.…”

Magnitude of the Root effect in red blood cells and haemoglobin solutions of fishes: a tribute to August Krogh

“…A choroid rete mirabile of the eye and a swimbladder rete mirabile are absent in early ray‐finned fishes such as sturgeons (Berenbrink et al. 2005, Brauner & Berenbrink 2007) and the physiological role of a Root effect in species such as sturgeons and gars is enigmatic, given that a Root effect may impair full Hb O 2 loading in gill blood during general acidosis. However, higher specific buffer values of sturgeon Hbs, lower maximal Root effects and lower haemolysate pH values required for half‐maximal Root effects in these species may reduce the cost of possessing a Root effect considerably compared with typical teleosts (Berenbrink et al.…”

In vivored blood cell sickling and mechanism of recovery in whiting,Merlangius merlangus

“…The apparent cooperativity constants for low-pH-induced sickling suggest highly cooperative proton binding to Hb during the sickling process. In the absence of catecholamines, protons are usually passively distributed across the RBC membrane, with changes in plasma pH causing distinctly smaller changes in intracellular pH, as also seen in the close relative of whiting, the Atlantic cod (Berenbrink and Bridges, 1994a;Berenbrink and Bridges, 1994b) (for a review, see Brauner and Berenbrink, 2007). When sickling is more appropriately related to intracellular pH changes in the vicinity of Hb, even higher cooperativity constants can be calculated.…”

Regulation of erythrocyte function: Multiple evolutionary solutions for respiratory gas transport and its regulation in fish

“…1 The low O 2 availability of water is thought to have been an important selective force in the evolution of respiratory systems in fish. 10 Apart from mammals, all vertebrates have erythrocytes that are nucleated and contain other cell organelles, which may partly explain why many features of the regulation of erythrocyte function, important for the different environmental adaptations in fish, are not utilized in air-breathing mammals with their organelle-free erythrocytes. 5 Three major alternative solutions in the gas transport by erythrocytes have evolved in fish: that employed by agnathans, 6 that used by elasmobranchs, 7,8 and that found in teleosts.…”

“…As a result, the O 2 transport system of fish is the most versatile among vertebrates, [2][3][4] with the most extreme adaptation in fishes being the ability to breathe air which occurs in approximately 500 species. [10][11][12] This is an important point to consider when using teleost fishes such as zebrafish (Danio rerio) to study O 2 -dependent phenomena with a mammalian biomedical application: the zebrafish is a very hypoxia-tolerant tropical cyprinid. 9 The pattern employed by elasmobranchs may be the most representative of fish ancestors of the tetrapods and hence mammals.…”

“…Early studies on agnathan Hbs failed to see aggregation (and cooperativity), 56 because dilution favours monomerization. 60 Two significant properties of lamprey Hb within erythrocytes are the marked Bohr effect (with a Bohr coefficient of around −1, 56 which contrasts with a much lower mammalian value of around −0.5 61 ), and the reduction in the O 2 carrying capacity of the blood at air-saturated O 2 tensions at low pH, 56 a phenomenon that is more commonly associated with the blood of teleost fishes, 62 where it is referred to as the "Root effect" (for review see: 10,63 ). [57][58][59] A schematic depiction of aggregation-dependent O 2 affinity regulation is given in Figure 3.…”

Magnitude of the Root effect in red blood cells and haemoglobin solutions of fishes: a tribute to August Krogh

“…A choroid rete mirabile of the eye and a swimbladder rete mirabile are absent in early ray‐finned fishes such as sturgeons (Berenbrink et al. 2005, Brauner & Berenbrink 2007) and the physiological role of a Root effect in species such as sturgeons and gars is enigmatic, given that a Root effect may impair full Hb O 2 loading in gill blood during general acidosis. However, higher specific buffer values of sturgeon Hbs, lower maximal Root effects and lower haemolysate pH values required for half‐maximal Root effects in these species may reduce the cost of possessing a Root effect considerably compared with typical teleosts (Berenbrink et al.…”

In vivored blood cell sickling and mechanism of recovery in whiting,Merlangius merlangus

“…The apparent cooperativity constants for low-pH-induced sickling suggest highly cooperative proton binding to Hb during the sickling process. In the absence of catecholamines, protons are usually passively distributed across the RBC membrane, with changes in plasma pH causing distinctly smaller changes in intracellular pH, as also seen in the close relative of whiting, the Atlantic cod (Berenbrink and Bridges, 1994a;Berenbrink and Bridges, 1994b) (for a review, see Brauner and Berenbrink, 2007). When sickling is more appropriately related to intracellular pH changes in the vicinity of Hb, even higher cooperativity constants can be calculated.…”

Regulation of erythrocyte function: Multiple evolutionary solutions for respiratory gas transport and its regulation in fish

“…1 The low O 2 availability of water is thought to have been an important selective force in the evolution of respiratory systems in fish. 10 Apart from mammals, all vertebrates have erythrocytes that are nucleated and contain other cell organelles, which may partly explain why many features of the regulation of erythrocyte function, important for the different environmental adaptations in fish, are not utilized in air-breathing mammals with their organelle-free erythrocytes. 5 Three major alternative solutions in the gas transport by erythrocytes have evolved in fish: that employed by agnathans, 6 that used by elasmobranchs, 7,8 and that found in teleosts.…”

“…As a result, the O 2 transport system of fish is the most versatile among vertebrates, [2][3][4] with the most extreme adaptation in fishes being the ability to breathe air which occurs in approximately 500 species. [10][11][12] This is an important point to consider when using teleost fishes such as zebrafish (Danio rerio) to study O 2 -dependent phenomena with a mammalian biomedical application: the zebrafish is a very hypoxia-tolerant tropical cyprinid. 9 The pattern employed by elasmobranchs may be the most representative of fish ancestors of the tetrapods and hence mammals.…”

“…Early studies on agnathan Hbs failed to see aggregation (and cooperativity), 56 because dilution favours monomerization. 60 Two significant properties of lamprey Hb within erythrocytes are the marked Bohr effect (with a Bohr coefficient of around −1, 56 which contrasts with a much lower mammalian value of around −0.5 61 ), and the reduction in the O 2 carrying capacity of the blood at air-saturated O 2 tensions at low pH, 56 a phenomenon that is more commonly associated with the blood of teleost fishes, 62 where it is referred to as the "Root effect" (for review see: 10,63 ). [57][58][59] A schematic depiction of aggregation-dependent O 2 affinity regulation is given in Figure 3.…”