Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua)
Thesis (Ph.D.)--Memorial University of Newfoundland, 2010. Biology Includes bibliographical references Currently, little information exists on how chronic hypoxia influences fish physiology. Thus, a comprehensive examination of how this ecologically-relevant environmental challenge affects the cardi...
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ftmemorialunivdc:oai:collections.mun.ca:theses4/123445 2023-05-15T15:26:59+02:00 Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) Petersen, Lene Hebsgaard. Memorial University of Newfoundland. Dept. of Biology 2010 xx, 232 leaves : ill. Image/jpeg; Application/pdf http://collections.mun.ca/cdm/ref/collection/theses4/id/123445 Eng eng Electronic Theses and Dissertations (28.29 MB) -- http://collections.mun.ca/PDFs/theses/Petersen_Lene.pdf a3315215 http://collections.mun.ca/cdm/ref/collection/theses4/id/123445 The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries Atlantic cod--Cardiovascular system Atlantic cod--Physiology Atlantic cod--Respiration Text 2010 ftmemorialunivdc 2015-08-06T19:22:24Z Thesis (Ph.D.)--Memorial University of Newfoundland, 2010. Biology Includes bibliographical references Currently, little information exists on how chronic hypoxia influences fish physiology. Thus, a comprehensive examination of how this ecologically-relevant environmental challenge affects the cardiorespiratory physiology, exercise performance and hypoxia tolerance of Atlantic cod ( Gadus morhua ) was performed. -- Exposure to acute hypoxia (Pw O2 8-9 kPa) lowered the Ucrit of normoxic-acclimated cod by approx. 30%, and this was associated with large decreases in max. oxygen consumption (MO2 ), metabolic scope (≥ 50%), and maximum heart rate (f H) and cardiac output (Q) (by 16 and 22%). Hypoxic acclimation (6-12 weeks at 10°C; Pw O2 8-9 kPa) elevated normoxic MO2 (standard by 27 %; routine by 44%) compared with normoxic controls, but did not influence Ucrit , max. MO2 or metabolic scope under either normoxia or hypoxia. Further, although, resting and maximum values for Q were significantly diminished in hypoxic-acclimated cod due to lower values for stroke volume (Sv ), increased fH partially compensated for the latter, and hypoxic-acclimated cod were able to consume more oxygen for a given cardiac output. -- This lower in vivo cardiac pumping capacity proved not to be a regulated decrease as hypoxic acclimation reduced in situ values for maximum Sv , the scope for Sv , and consequently maximum cardiac output (Qmax ) (by 19%). However, hypoxic-acclimated fish were able to sustain Q better under hypoxia, and the recovery of Q max (compared to initial Qmax ) was significantly improved (94 vs. 83%) as compared with normoxic controls. -- Although several physiological adjustments had taken place during the 6-12 weeks of hypoxic acclimation [increased fH elevated hematocrit (Hct) by 11 % and [Hb] by 14 %; enhanced tissue oxygen extraction efficiency by ∼ 15%; and a more robust stress response (2-8 fold higher levels of plasma catecholamines at Pw O2 's of 5.3 and 2.7 kPa)], these adjustments were only successful in improving the cod's critical oxygen tension (Pcrit of normoxic and hypoxic-acclimated cod 8.1 ± 0.5 vs. 6.6 ± 0.6 kPa, respectively), not the cod's hypoxia tolerance (Hcrit = 4.3 ± 0.2 vs. 4.8 ± 0.3 kPa). Finally, the significance of the enhanced stress response in hypoxic-acclimated cod for cardiac function is uncertain as this species' heart is minimally responsive to adrenergic stimulation, and hypoxic-acclimation reduced the heart's adrenergic responsiveness further. Text atlantic cod Gadus morhua Newfoundland studies University of Newfoundland Memorial University of Newfoundland: Digital Archives Initiative (DAI) |
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Memorial University of Newfoundland: Digital Archives Initiative (DAI) |
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ftmemorialunivdc |
language |
English |
topic |
Atlantic cod--Cardiovascular system Atlantic cod--Physiology Atlantic cod--Respiration |
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Atlantic cod--Cardiovascular system Atlantic cod--Physiology Atlantic cod--Respiration Petersen, Lene Hebsgaard. Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) |
topic_facet |
Atlantic cod--Cardiovascular system Atlantic cod--Physiology Atlantic cod--Respiration |
description |
Thesis (Ph.D.)--Memorial University of Newfoundland, 2010. Biology Includes bibliographical references Currently, little information exists on how chronic hypoxia influences fish physiology. Thus, a comprehensive examination of how this ecologically-relevant environmental challenge affects the cardiorespiratory physiology, exercise performance and hypoxia tolerance of Atlantic cod ( Gadus morhua ) was performed. -- Exposure to acute hypoxia (Pw O2 8-9 kPa) lowered the Ucrit of normoxic-acclimated cod by approx. 30%, and this was associated with large decreases in max. oxygen consumption (MO2 ), metabolic scope (≥ 50%), and maximum heart rate (f H) and cardiac output (Q) (by 16 and 22%). Hypoxic acclimation (6-12 weeks at 10°C; Pw O2 8-9 kPa) elevated normoxic MO2 (standard by 27 %; routine by 44%) compared with normoxic controls, but did not influence Ucrit , max. MO2 or metabolic scope under either normoxia or hypoxia. Further, although, resting and maximum values for Q were significantly diminished in hypoxic-acclimated cod due to lower values for stroke volume (Sv ), increased fH partially compensated for the latter, and hypoxic-acclimated cod were able to consume more oxygen for a given cardiac output. -- This lower in vivo cardiac pumping capacity proved not to be a regulated decrease as hypoxic acclimation reduced in situ values for maximum Sv , the scope for Sv , and consequently maximum cardiac output (Qmax ) (by 19%). However, hypoxic-acclimated fish were able to sustain Q better under hypoxia, and the recovery of Q max (compared to initial Qmax ) was significantly improved (94 vs. 83%) as compared with normoxic controls. -- Although several physiological adjustments had taken place during the 6-12 weeks of hypoxic acclimation [increased fH elevated hematocrit (Hct) by 11 % and [Hb] by 14 %; enhanced tissue oxygen extraction efficiency by ∼ 15%; and a more robust stress response (2-8 fold higher levels of plasma catecholamines at Pw O2 's of 5.3 and 2.7 kPa)], these adjustments were only successful in improving the cod's critical oxygen tension (Pcrit of normoxic and hypoxic-acclimated cod 8.1 ± 0.5 vs. 6.6 ± 0.6 kPa, respectively), not the cod's hypoxia tolerance (Hcrit = 4.3 ± 0.2 vs. 4.8 ± 0.3 kPa). Finally, the significance of the enhanced stress response in hypoxic-acclimated cod for cardiac function is uncertain as this species' heart is minimally responsive to adrenergic stimulation, and hypoxic-acclimation reduced the heart's adrenergic responsiveness further. |
author2 |
Memorial University of Newfoundland. Dept. of Biology |
format |
Text |
author |
Petersen, Lene Hebsgaard. |
author_facet |
Petersen, Lene Hebsgaard. |
author_sort |
Petersen, Lene Hebsgaard. |
title |
Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) |
title_short |
Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) |
title_full |
Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) |
title_fullStr |
Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) |
title_full_unstemmed |
Effects of chronic hypoxia on the cardiorespiratory physiology of Atlantic cod (Gadus morhua) |
title_sort |
effects of chronic hypoxia on the cardiorespiratory physiology of atlantic cod (gadus morhua) |
publishDate |
2010 |
url |
http://collections.mun.ca/cdm/ref/collection/theses4/id/123445 |
genre |
atlantic cod Gadus morhua Newfoundland studies University of Newfoundland |
genre_facet |
atlantic cod Gadus morhua Newfoundland studies University of Newfoundland |
op_source |
Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries |
op_relation |
Electronic Theses and Dissertations (28.29 MB) -- http://collections.mun.ca/PDFs/theses/Petersen_Lene.pdf a3315215 http://collections.mun.ca/cdm/ref/collection/theses4/id/123445 |
op_rights |
The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. |
_version_ |
1766357440894337024 |