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Title: Metabolic adjustments in two Amazonian cichlids exposed to hypoxia and anoxia
Authors: Chippari-Gomes, Adriana Regina
Gomes, Levy de Carvalho
Lopes, Nilva Pereira
Val, Adalberto Luis
Val, Vera Maria Fonseca Almeida e
Keywords: Citrate Synthase
Lactate Dehydrogenase
Malate Dehydrogenase
Pyruvate Kinase
Anaerobic Metabolism
Animals Experiment
Animals Tissue
Comparative Study
Concentration (parameters)
Controlled Study
Down Regulation
Enzyme Activity
Glucose Blood Level
Glycogen Analysis
Heart Muscle
Lactate Blood Level
Muscle Tissue
Oxygen Consumption
Priority Journal
Muscle, Skeletal
Tissue Level
Astronotus Crassipinnis
Symphysodon Aequifasciatus
Issue Date: 2005
metadata.dc.publisher.journal: Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
metadata.dc.relation.ispartof: Volume 141, Número 3, Pags. 347-355
Abstract: The effects of graded hypoxia on the physiological and biochemical responses were examined in two closely related species of cichlids of the Amazon: Astronotus crassipinnis and Symphysodon aequifasciatus. Ten fish of each species were exposed to graded hypoxia for 8 h in seven oxygen concentrations (5.92, 3.15, 1.54, 0.79, 0.60, 0.34, and 0.06 mg O2 L-1), with the aim to evaluate hypoxia tolerance and metabolic adjustments, where plasma glucose and lactate levels, hepatic and muscle glycogen contents, and maximum enzyme activities (PK, LDH, MDH and CS) in skeletal and cardiac muscles were measured. Another experimental set was done to quantify oxygen consumption (MO2) and opercular movements in two oxygen concentrations. Hypoxia tolerance differed between the two species. Astronotus crassipinnis was able to tolerate anoxia for 178 min while S. aequifasciatus was able to withstand 222 min exposure in deep hypoxia (0.75 mg O2 L-1). Suppressed MO2 was observed during exposure to 0.34 (A. crassipinnis) and 0.79 mg O2 L-1 (S. aequifasciatus), while opercular movements increased in both species exposed to hypoxia. Higher levels of muscle and liver glycogen and larger hypoxia-induced increases in plasma glucose and lactate were observed in A. crassipinnis, which showed a higher degree of hypoxia tolerance. Changes in enzyme levels were tissue-specific and differed between species suggesting differential abilities in down-regulating oxidative pathways and increasing anaerobic metabolism. Based on the present data, we conclude that these animals are good anaerobes and highly adapted to their environment, which is allowed by their abilities to regulate metabolic pathways and adjust their enzyme levels. © 2005 Elsevier Inc. All rights reserved.
metadata.dc.identifier.doi: 10.1016/j.cbpc.2005.04.006
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