Rapid blood acid-base regulation by European sea bass (Dicentrarchus labrax) in response to sudden exposure to high environmental CO2.

Autor:	Montgomery DW; Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK., Kwan GT; Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.; National Oceanic and Atmospheric Administration Fisheries Service, Southwest Fisheries Science Center, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USA., Davison WG; Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK., Finlay J; Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK., Berry A; Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK., Simpson SD; Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK., Engelhard GH; Centre for Environment, Fisheries & Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR33 0HT, UK.; School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK., Birchenough SNR; Centre for Environment, Fisheries & Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR33 0HT, UK., Tresguerres M; Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA., Wilson RW; Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK.
Jazyk:	angličtina
Zdroj:	The Journal of experimental biology [J Exp Biol] 2022 Jan 15; Vol. 225 (2). Date of Electronic Publication: 2022 Jan 26.
DOI:	10.1242/jeb.242735
Abstrakt:	Fish in coastal ecosystems can be exposed to acute variations in CO2 of between 0.2 and 1 kPa CO2 (2000-10,000 µatm). Coping with this environmental challenge will depend on the ability to rapidly compensate for the internal acid-base disturbance caused by sudden exposure to high environmental CO2 (blood and tissue acidosis); however, studies about the speed of acid-base regulatory responses in marine fish are scarce. We observed that upon sudden exposure to ∼1 kPa CO2, European sea bass (Dicentrarchus labrax) completely regulate erythrocyte intracellular pH within ∼40 min, thus restoring haemoglobin-O2 affinity to pre-exposure levels. Moreover, blood pH returned to normal levels within ∼2 h, which is one of the fastest acid-base recoveries documented in any fish. This was achieved via a large upregulation of net acid excretion and accumulation of HCO3- in blood, which increased from ∼4 to ∼22 mmol l-1. While the abundance and intracellular localisation of gill Na+/K+-ATPase (NKA) and Na+/H+ exchanger 3 (NHE3) remained unchanged, the apical surface area of acid-excreting gill ionocytes doubled. This constitutes a novel mechanism for rapidly increasing acid excretion during sudden blood acidosis. Rapid acid-base regulation was completely prevented when the same high CO2 exposure occurred in seawater with experimentally reduced HCO3- and pH, probably because reduced environmental pH inhibited gill H+ excretion via NHE3. The rapid and robust acid-base regulatory responses identified will enable European sea bass to maintain physiological performance during large and sudden CO2 fluctuations that naturally occur in coastal environments. Competing Interests: Competing interests The authors declare no competing or financial interests. (© 2022. Published by The Company of Biologists Ltd.)
Databáze:	MEDLINE
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