Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus

Scott, Graham R.; Wood, Chris M.; Sloman, Katherine A.; Iftikar, Fathima I.; Boeck, Gudrun de; Almeida-Val, Vera Maria Fonseca; Val, Adalberto Luis

Artigo

Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus

This study determined the respiratory responses to progressive hypoxia in oscar, an extremely hypoxia-tolerant Amazonian cichlid. Oscar depressed oxygen consumption rates (over(M, ̇)O2), beginning at a critical O2 tension (Pcrit) of 46 Torr, to only 14% of normoxic rates at 10 Torr. Total ventilatio...

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Autor principal:	Scott, Graham R.
Outros Autores:	Wood, Chris M., Sloman, Katherine A., Iftikar, Fathima I., Boeck, Gudrun de, Almeida-Val, Vera Maria Fonseca, Val, Adalberto Luis
Grau:	Artigo
Idioma:	English
Publicado em:	Respiratory Physiology and Neurobiology 2020
Assuntos:	Animals Experiment Breathing Cell Respiration Cichlid Controlled Study Fish Gas Exchange Gill Hypoxia Nonhuman Oxygen Consumption Priority Journal Adaptation, Physiological Anaerobic Threshold Animal Anoxia Cell Respiration Cichlids Energy Metabolism Gills Lactic Acid Oxygen Consumption Respiratory Mechanics
Acesso em linha:	https://repositorio.inpa.gov.br/handle/1/18543

id	oai:repositorio:1-18543
recordtype	dspace
spelling	oai:repositorio:1-18543 Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus Scott, Graham R. Wood, Chris M. Sloman, Katherine A. Iftikar, Fathima I. Boeck, Gudrun de Almeida-Val, Vera Maria Fonseca Val, Adalberto Luis Animals Experiment Breathing Cell Respiration Cichlid Controlled Study Fish Gas Exchange Gill Hypoxia Nonhuman Oxygen Consumption Priority Journal Adaptation, Physiological Anaerobic Threshold Animal Anoxia Cell Respiration Cichlids Energy Metabolism Gills Lactic Acid Oxygen Consumption Respiratory Mechanics This study determined the respiratory responses to progressive hypoxia in oscar, an extremely hypoxia-tolerant Amazonian cichlid. Oscar depressed oxygen consumption rates (over(M, ̇)O2), beginning at a critical O2 tension (Pcrit) of 46 Torr, to only 14% of normoxic rates at 10 Torr. Total ventilation (over(V, ̇)w) increased up to 4-fold, entirely due to a rise in ventilatory stroke volume (no change in ventilatory frequency), and water convection requirement (over(V, ̇)w / over(M, ̇)O2) increased substantially (up to 15-fold). Gill O2 extraction fell steadily, from 60% down to 40%. Although O2 transfer factor (an index of gill O2 diffusion capacity) increased transiently in moderate hypoxia, it decreased at 10 Torr, which may have caused the increased expired-arterial PO2 difference. Venous PO2 was always very low (≤7 Torr). Anaerobic metabolism made a significant contribution to ATP supply, indicated by a 3-fold increase in plasma lactate that resulted in an uncompensated metabolic acidosis. Respiration of isolated gill cells was not inhibited until below 5 Torr; because gill water PO2 always exceeded this value, hypoxic ion flux arrest in oscars [Wood et al., Am. J. Physiol. Reg. Integr. Comp. Physiol. 292, R2048-R2058, 2007] is probably not caused by O2 limitation in ionocytes. We conclude that metabolic depression and tolerance of anaerobic bi-products, rather than a superior capacity for O2 supply, allow oscar to thrive in extreme hypoxia in the Amazon. © 2008 Elsevier B.V. All rights reserved. 2020-06-15T22:02:05Z 2020-06-15T22:02:05Z 2008 Artigo https://repositorio.inpa.gov.br/handle/1/18543 10.1016/j.resp.2008.05.001 en Volume 162, Número 2, Pags. 109-116 Restrito Respiratory Physiology and Neurobiology
institution	Instituto Nacional de Pesquisas da Amazônia - Repositório Institucional
collection	INPA-RI
language	English
topic	Animals Experiment Breathing Cell Respiration Cichlid Controlled Study Fish Gas Exchange Gill Hypoxia Nonhuman Oxygen Consumption Priority Journal Adaptation, Physiological Anaerobic Threshold Animal Anoxia Cell Respiration Cichlids Energy Metabolism Gills Lactic Acid Oxygen Consumption Respiratory Mechanics
spellingShingle	Animals Experiment Breathing Cell Respiration Cichlid Controlled Study Fish Gas Exchange Gill Hypoxia Nonhuman Oxygen Consumption Priority Journal Adaptation, Physiological Anaerobic Threshold Animal Anoxia Cell Respiration Cichlids Energy Metabolism Gills Lactic Acid Oxygen Consumption Respiratory Mechanics Scott, Graham R. Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus
topic_facet	Animals Experiment Breathing Cell Respiration Cichlid Controlled Study Fish Gas Exchange Gill Hypoxia Nonhuman Oxygen Consumption Priority Journal Adaptation, Physiological Anaerobic Threshold Animal Anoxia Cell Respiration Cichlids Energy Metabolism Gills Lactic Acid Oxygen Consumption Respiratory Mechanics
description	This study determined the respiratory responses to progressive hypoxia in oscar, an extremely hypoxia-tolerant Amazonian cichlid. Oscar depressed oxygen consumption rates (over(M, ̇)O2), beginning at a critical O2 tension (Pcrit) of 46 Torr, to only 14% of normoxic rates at 10 Torr. Total ventilation (over(V, ̇)w) increased up to 4-fold, entirely due to a rise in ventilatory stroke volume (no change in ventilatory frequency), and water convection requirement (over(V, ̇)w / over(M, ̇)O2) increased substantially (up to 15-fold). Gill O2 extraction fell steadily, from 60% down to 40%. Although O2 transfer factor (an index of gill O2 diffusion capacity) increased transiently in moderate hypoxia, it decreased at 10 Torr, which may have caused the increased expired-arterial PO2 difference. Venous PO2 was always very low (≤7 Torr). Anaerobic metabolism made a significant contribution to ATP supply, indicated by a 3-fold increase in plasma lactate that resulted in an uncompensated metabolic acidosis. Respiration of isolated gill cells was not inhibited until below 5 Torr; because gill water PO2 always exceeded this value, hypoxic ion flux arrest in oscars [Wood et al., Am. J. Physiol. Reg. Integr. Comp. Physiol. 292, R2048-R2058, 2007] is probably not caused by O2 limitation in ionocytes. We conclude that metabolic depression and tolerance of anaerobic bi-products, rather than a superior capacity for O2 supply, allow oscar to thrive in extreme hypoxia in the Amazon. © 2008 Elsevier B.V. All rights reserved.
format	Artigo
author	Scott, Graham R.
author2	Wood, Chris M. Sloman, Katherine A. Iftikar, Fathima I. Boeck, Gudrun de Almeida-Val, Vera Maria Fonseca Val, Adalberto Luis
author2Str	Wood, Chris M. Sloman, Katherine A. Iftikar, Fathima I. Boeck, Gudrun de Almeida-Val, Vera Maria Fonseca Val, Adalberto Luis
title	Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus
title_short	Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus
title_full	Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus
title_fullStr	Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus
title_full_unstemmed	Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus
title_sort	respiratory responses to progressive hypoxia in the amazonian oscar, astronotus ocellatus
publisher	Respiratory Physiology and Neurobiology
publishDate	2020
url	https://repositorio.inpa.gov.br/handle/1/18543
_version_	1787142609462886400
score	11.755432

Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus

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