TY - JOUR
T1 - Water balance and renal function in two species of African lungfish Protopterus dolloi and Protopterus annectens
AU - Patel, Monika
AU - Iftikar, Fathima I.
AU - Smith, Richard W.
AU - Ip, Yuen K.
AU - Wood, Chris M.
N1 - Funding Information:
Funded by an NSERC Discovery grant to CMW, who is supported by the Canada Research Chair Program. We thank Linda Daio and Sunita Nadella (McMaster University), and Dr. Mike Wilkie (Wilfred Laurier University, Waterloo, ON, Canada) for their assistance.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2009/2
Y1 - 2009/2
N2 - The basic physiology of water balance and kidney function was characterized in two species of African lungfish, Protopterus dolloi and Protopterus annectens. Diffusive water efflux rate constants were low (0.13 h- 1-0.38 h- 1 in various series) relative to values in freshwater teleost fish. Efflux rate constants increased approximately 3-fold after feeding in both species, and were greatly decreased after 8 months terrestrialization (P. dolloi only tested). Urine flow rates (UFR, 3.9-5.2 mL kg- 1 h- 1) and glomerular filtration rates (GFR, 6.6-9.3 mL kg- 1 h- 1) were quite high relative to values in most freshwater teleosts. However urinary ion excretion rates were low, with net re-absorption of > 99% Na+, > 98% Cl-, and > 78% Ca2+ from the primary filtrate, comparable to teleosts. Net water re-absorption was significantly greater in P. dolloi (56%) than in P. annectens (23%). We conclude that renal function in lungfish is similar to that in other primitive freshwater fish, but there is an interesting dichotomy between diffusive and osmotic permeabilities. Aquatic lungfish have low diffusive water permeability, an important pre-adaptation to life on land, and in accord with greatly reduced gill areas and low metabolic rates. However osmotic permeability is high, 4-12 times greater than diffusive permeability. A role for aquaporins in this dichotomy is speculated.
AB - The basic physiology of water balance and kidney function was characterized in two species of African lungfish, Protopterus dolloi and Protopterus annectens. Diffusive water efflux rate constants were low (0.13 h- 1-0.38 h- 1 in various series) relative to values in freshwater teleost fish. Efflux rate constants increased approximately 3-fold after feeding in both species, and were greatly decreased after 8 months terrestrialization (P. dolloi only tested). Urine flow rates (UFR, 3.9-5.2 mL kg- 1 h- 1) and glomerular filtration rates (GFR, 6.6-9.3 mL kg- 1 h- 1) were quite high relative to values in most freshwater teleosts. However urinary ion excretion rates were low, with net re-absorption of > 99% Na+, > 98% Cl-, and > 78% Ca2+ from the primary filtrate, comparable to teleosts. Net water re-absorption was significantly greater in P. dolloi (56%) than in P. annectens (23%). We conclude that renal function in lungfish is similar to that in other primitive freshwater fish, but there is an interesting dichotomy between diffusive and osmotic permeabilities. Aquatic lungfish have low diffusive water permeability, an important pre-adaptation to life on land, and in accord with greatly reduced gill areas and low metabolic rates. However osmotic permeability is high, 4-12 times greater than diffusive permeability. A role for aquaporins in this dichotomy is speculated.
KW - Clearance ratio
KW - Diffusive permeability
KW - Feeding
KW - Osmotic permeability
KW - Terrestrialization
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U2 - 10.1016/j.cbpa.2008.09.014
DO - 10.1016/j.cbpa.2008.09.014
M3 - Article
C2 - 18835584
AN - SCOPUS:57649087638
VL - 152
SP - 149
EP - 157
JO - Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
JF - Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
SN - 1095-6433
IS - 2
ER -