Use este identificador para citar ou linkar para este item: https://repositorio.inpa.gov.br/handle/1/17203
Título: Air breathing and aquatic gas exchange during hypoxia in armoured catfish
Autor: Scott, Graham R.
Matey, Victoria E.
Mendoza, Julie Anne
Gilmour, Kathleen M.
Perry, Steven Franklin
Val, Vera Maria Fonseca Almeida e
Val, Adalberto Luis
Palavras-chave: Citrate Synthase
Cytochrome C Oxidase
Fish Protein
Lactate Dehydrogenase
Myoglobin
Phosphoenolpyruvate Carboxykinase (atp)
Pyruvate Kinase
Air
Anatomy And Histology
Animals
Brain
Breathing
Catfish
Gill
Hypoxia
Liver
Metabolism
Oxygen Consumption
Pathophysiology
Physiology
Microscopy, Electron, Scanning
Muscle, Skeletal
Ultrastructure
Air
Animal
Brain
Catfishes
Citrate (si)-synthase
Electron Transport Complex Iv
Fish Proteins
Gills
Hypoxia
L-lactate Dehydrogenase
Liver
Microscopy, Electron, Scanning
Muscle, Skeletal
Myoglobin
Oxygen Consumption
Phosphoenolpyruvate Carboxykinase (atp)
Pyruvate Kinase
Respiration
Data do documento: 2017
Revista: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
É parte de: Volume 187, Número 1, Pags. 117-133
Abstract: Air breathing in fish is commonly believed to have arisen as an adaptation to aquatic hypoxia. The effectiveness of air breathing for tissue O2 supply depends on the ability to avoid O2 loss as oxygenated blood from the air-breathing organ passes through the gills. Here, we evaluated whether the armoured catfish (Hypostomus aff. pyreneusi)—a facultative air breather—can avoid branchial O2 loss while air breathing in aquatic hypoxia, and we measured various other respiratory and metabolic traits important for O2 supply and utilization. Fish were instrumented with opercular catheters to measure the O2 tension (PO2) of expired water, and air breathing and aquatic respiration were measured during progressive stepwise hypoxia in the water. Armoured catfish exhibited relatively low rates of O2 consumption and gill ventilation, and gill ventilation increased in hypoxia due primarily to increases in ventilatory stroke volume. Armoured catfish began air breathing at a water PO2 of 2.5 kPa, and both air-breathing frequency and hypoxia tolerance (as reflected by PO2 at loss of equilibrium, LOE) was greater in individuals with a larger body mass. Branchial O2 loss, as reflected by higher PO2 in expired than in inspired water, was observed in a minority (4/11) of individuals as water PO2 approached that at LOE. Armoured catfish also exhibited a gill morphology characterized by short filaments bearing short fused lamellae, large interlamellar cell masses, low surface area, and a thick epithelium that increased water-to-blood diffusion distance. Armoured catfish had a relatively low blood-O2 binding affinity when sampled in normoxia (P50 of 3.1 kPa at pH 7.4), but were able to rapidly increase binding affinity during progressive hypoxia exposure (to a P50 of 1.8 kPa). Armoured catfish also had low activities of several metabolic enzymes in white muscle, liver, and brain. Therefore, low rates of metabolism and gill ventilation, and a reduction in branchial gas-exchange capacity, may help minimize branchial O2 loss in armoured catfish while air breathing in aquatic hypoxia. © 2016, Springer-Verlag Berlin Heidelberg.
DOI: 10.1007/s00360-016-1024-y
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