» Articles » PMID: 20095822

The Ionoregulatory Responses to Hypoxia in the Freshwater Rainbow Trout Oncorhynchus Mykiss

Overview
Date 2010 Jan 26
PMID 20095822
Citations 12
Authors
Affiliations
Soon will be listed here.
Abstract

We utilized the rainbow trout, a hypoxia-intolerant freshwater teleost, to examine ionoregulatory changes at the gills during hypoxia. Progressive mild hypoxia led first to a significant elevation (by 21%) in J(Na)(influx) (measured with 22Na), but at 4-h hypoxia when PCO2 reached approximately 110 mmHg, there was a 79% depression in J(Na)(influx). Influx remained depressed during the first hour of normoxic recovery but was restored back to control rates thereafter; there were no significant changes in J(Na)(efflux) or J(Na)(net). A more prolonged (8 h) and severe hypoxic (approximately 80 mmHg) exposure induced a triphasic response whereby J(Na)(influx) was significantly elevated during the first hour, as during mild hypoxia, but returned to control rates during the subsequent 3 h. Thereafter, rates started to gradually increase and remained significantly elevated by about 38% through to 8 h of hypoxia. A similar triphasic trend was observed with J(Na)(efflux) but with larger changes than in J(Na)(influx), such that negative Na+ balance occurred during the hypoxic exposure. Net K+ loss rates to the water approximately doubled. There were no significant alterations in ammonia excretion rates in either of the hypoxia regimes. Branchial Na+/K+-ATPase activity did not change during 4 h at PO2 approximately 80 mmHg or return to normoxia; H+-ATPase activity also did not change during hypoxia but was significantly depressed by approximately 75% after 6 h of normoxic recovery. Scanning electron microscopy revealed that within 1 h of exposure to PO2 approximately 80 mmHg, exposed mitochondria-rich cell (MRC) numbers increased by 30%, while individual MRC exposed surface area and total MRC surface area both increased by three- to fourfold. MRC numbers had decreased below control levels by 4 h of hypoxia, but surface exposure remained elevated by approximately twofold, a response that persisted through 6 h of normoxic recovery. Environmental hypoxia induces complex changes in gill ionoregulatory function in this hypoxia-intolerant species that are very different from those recently reported in the hypoxia-tolerant Amazonian oscar.

Citing Articles

The mayfly Neocloeon triangulifer senses decreasing oxygen availability (PO2) and responds by reducing ion uptake and altering gene expression.

Cochran J, Buchwalter D J Exp Biol. 2024; 227(23).

PMID: 39422090 PMC: 11634025. DOI: 10.1242/jeb.247916.


Osmo-respiratory compromise in the mosshead sculpin (Clinocottus globiceps): effects of temperature, hypoxia, and re-oxygenation on rates of diffusive water flux and oxygen uptake.

Onukwufor J, Somo D, Richards J, Wood C Fish Physiol Biochem. 2023; 49(5):853-866.

PMID: 37526893 DOI: 10.1007/s10695-023-01226-0.


Osmorespiratory compromise in an elasmobranch: oxygen consumption, ventilation and nitrogen metabolism during recovery from exhaustive exercise in dogfish sharks (Squalus suckleyi).

Giacomin M, Schulte P, Wood C J Comp Physiol B. 2022; 192(5):647-657.

PMID: 35838789 DOI: 10.1007/s00360-022-01447-4.


Chemical niches and ionoregulatory traits: applying ionoregulatory physiology to the conservation management of freshwater fishes.

Zimmer A, Goss G, Glover C Conserv Physiol. 2021; 9(1):coab066.

PMID: 34512989 PMC: 8415428. DOI: 10.1093/conphys/coab066.


Is aquaporin-3 involved in water-permeability changes in the killifish during hypoxia and normoxic recovery, in freshwater or seawater?.

Ruhr I, Wood C, Schauer K, Wang Y, Mager E, Stanton B J Exp Zool A Ecol Integr Physiol. 2020; 333(7):511-525.

PMID: 32548921 PMC: 7405550. DOI: 10.1002/jez.2393.