Document Detail

Low O2 acclimation shifts the hypoxia avoidance behaviour of snapper (Pagrus auratus) with only subtle changes in aerobic and anaerobic function.
MedLine Citation:
PMID:  23038727     Owner:  NLM     Status:  Publisher    
It was hypothesized that chronic hypoxia acclimation (preconditioning) would alter the behavioural low O(2) avoidance strategy of fish as a result of both aerobic and anaerobic physiological adaptations. Avoidance and physiological responses of juvenile snapper (Pagrus auratus) were therefore investigated following a 6 week period of moderate hypoxia exposure (10.2-12.1 kPa PO(2), 21 ± 1°C) and compared to those of normoxic controls (PO(2)= 20-21 kPa, 21 ± 1°C). The critical oxygen pressure (i.e. P(crit)) limit of both groups was unchanged at ~7 kPa, as were standard, routine and maximum metabolic rates. However, hypoxia acclimated fish showed increased tolerances to hypoxia in behavioral choice chambers by avoiding lower PO(2) levels (3.3 ± 0.7 vs 5.3 ± 1.1 kPa) without displaying greater perturbations of lactate or glucose. This behavioural change was associated with unexpected physiological adjustments. For example, a decrease in blood O(2) carrying capacity was observed after hypoxia-acclimation. Also unexpected was an increase in whole blood P(50) following acclimation to low O(2), perhaps facilitating Hb-O(2) off-loading to tissues. In addition, cardiac mitochondria measured in situ using permeabilised fibres showed improved O(2) uptake efficiencies. The proportion of the anaerobic enzyme lactate dehydrogenase (LDH), at least relative to the aerobic marker enzyme citrate synthase (CS), also increased in heart and skeletal red muscle indicating enhanced anaerobic potential, or in situ lactate metabolism, in these tissues. Overall these data suggest that a prioritization of O(2) delivery and O(2) utilization over O(2) uptake during long-term hypoxia may convey a significant survival benefit to snapper in terms of behavioural low O(2) tolerance.
Denham G Cook; Fathima I Iftikar; Daniel W Baker; Anthony J R Hickey; Neill A Herbert
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-4
Journal Detail:
Title:  The Journal of experimental biology     Volume:  -     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
The University of Auckland.
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