Anion exchange in the giant erythrocytes of African lungfish

• Published in: Journal of fish biology Vol. 62; no. 5; pp. 1044 - 1052
• Main Authors: Jensen, F. B., Brahm, J., Koldkjær, P., Wang, T., McKenzie, D. J., Taylor, E. W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.05.2003; Blackwell
• Subjects: anion exchange; Biological and medical sciences; chloride transport; erythrocytes; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects; lungfish; Oncorhynchus mykiss; Protopterus; Protopterus aethiopicus; temperature effects; Vertebrates: respiratory system; Temperature; chloride transport; Cell permeability; temperature effects; Red blood cell; Environmental factor; Freshwater environment; Vertebrata; Anions; Blood cell; Protopterus; lungfish; erythrocytes; Membrane transport; Pisces; Chlorides; anion exchange; Respiration
• ISSN: 0022-1112; 1095-8649
• DOI: 10.1046/j.1095-8649.2003.00095.x

Carbon dioxide transport in African lungfish Protopterus aethiopicus blood conformed to the typical vertebrate scheme, implying a crucial and rate‐limiting role of erythrocyte Cl–/HCO3– exchange. The rate coefficient for unidirectional Cl– efflux via the anion exchanger (k, s−1) increased with temperature in African lungfish, but values were well below those reported in other species. The erythrocytes of African lungfish were, however, very large (mean cellular volume = 6940 µm3), and the ratio of cell water volume to membrane surface area was high (VwAm−1 = 1·89). Hence, the apparent Cl– permeability (PCl = kVwAm−1, µm s−1) was close to that in other vertebrates. The plot of lnPCl against the inverse absolute temperature was left‐shifted in the tropical African lungfish compared to the temperate rainbow trout Oncorhynchus mykiss, which supports the idea that PCl is similar among animals when compared at their preferred temperatures. Also, Q10 for anion exchange calculated from PCl values in African lungfish was 2·0, supporting the idea that the temperature sensitivity of erythrocyte anion exchange matches the temperature sensitivity of CO2 production and transport in ectothermic vertebrates.