Avaliação hematológica e metabólica de Phrynops geoffroanus (Testudines: Chelidae) submetidos à hipóxia.
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Data
2018-02-27
Autores
Souza, Camila Zucchini
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Universidade Estadual Paulista (Unesp)
Resumo
A espécie Phrynops geoffroanus (Testudines: Chelidae), como outras espécies de quelônios dulcícolas, é considerada hipóxia-tolerante. Esses animais possuem diversos mecanismos que permitem tolerância a ambiente com pouca ou nenhuma oxigenação. O objetivo deste estudo consistiu em avaliar alterações na série vermelha e nas concentrações de intermediários energéticos em tecidos sanguíneo, hepático e muscular esquelético e cardíaco em hipóxia induzida. Os espécimes coletados em São José do Rio Preto-SP foram divididos em dois grupos: Normóxia, em que os animais tiveram acesso livre à superfície para respirarem e Hipóxia, no qual uma tela foi colocada abaixo do nível da água impedindo acesso dos indivíduos à superfície para respirarem, durante cinco horas. Houve diferença (p<0,05) entre os grupos, no qual os valores de hematócrito, concentração de hemoglobina, VGM e HGM aumentaram em Hipóxia, o hematócrito possivelmente aumenta como consequência da desidratação ou aumento do VGM, a hemoglobina aumenta a fim de tornar o transporte de oxigênio mais efetivo aos tecidos, o VGM e HGM salientam a adaptação do animal por meio do aumento do volume celular e aumento de hemoglobina no eritrócito. Em relação ao metabolismo, houve diferença nas concentrações de glicose e lactato nos três tecidos, glicogênio muscular e aminoácidos plasmáticos, sendo as maiores concentrações na condição de hipóxia. A hipóxia reflete diretamente na baixa taxa de glicogênio e alta taxa de glicose na musculatura, realizando assim, glicogenólise, também é constatada altas concentrações de lactato, no qual devido à ausência do oxigênio, faz com que as células musculares realizem fermentação láctica para produção de ATP. Com o intuito de diminuir a acidose lática, o alto teor de lactato é lançado no sangue, e este é direcionado às células hepáticas, sendo convertida em glicose pela gliconeogênese, lançada na corrente sanguínea para ser disponibilizada aos tecidos, constituindo o Ciclo de Cori. A alta concentração de aminoácidos plasmática pode ocorrer por hidrólise proteica, sendo utilizados como substrato de gliconeogênese ou lesão tecidual. Com base nos resultados obtidos, conclui-se que a espécie possui manutenção de reservas de combustíveis fermentáveis no organismo, para que seja possível realizar metabolismo anaeróbico e gliconeogênese, em privação de oxigênio.
The species Phrynops geoffroanus (Testudines: Chelidae), like other species of freshwater turtle, is considered hypoxia-tolerant. These animals have several mechanisms that allow tolerance to the environment with little or no oxygenation. The objective of this study was to evaluate alterations in the blood count and the concentrations of energetic intermediates in tissues blood, hepatic and skeletal and cardiac muscle induced hypoxia. The specimens collected in São José do Rio Preto-SP were divided into two groups: Normóxia, in which the animals had free access to the surface to breathe and Hypoxia, in which a screen was placed below the water level, preventing individuals from reaching the surface to breathe for five hours. There was a difference (p <0.05) between the groups, in which hematocrit, hemoglobin, VGM and HGM levels increased in Hypoxia, hematocrit possibly increased as a consequence of dehydration or increase of VGM, hemoglobin increases in order to rendering oxygen transport more effective to tissues, VGM and HGM emphasize the adaptation of the animal by increasing cell volume and increasing erythrocyte hemoglobin. Regarding metabolism, there were differences in glucose and lactate concentrations in the three tissues, muscle glycogen and plasma amino acids, with the highest concentrations in the hypoxia condition. Hypoxia directly reflects the low glycogen ratio and high glucose rate in the muscles, thus, glycogenolysis is also observed. High concentrations of lactate are also observed, due to the absence of oxygen, causing the muscle cells to perform lactic fermentation for the production of ATP. In order to decrease lactic acidosis, the high lactate content is released into the blood and is directed to the liver cells. It is converted to glucose by gluconeogenesis, which is released into the bloodstream to be made available to the tissues, constituting the Cori cycle. The high concentration of plasma amino acids can occur by protein hydrolysis, being used as substrate of gluconeogenesis or tissue injury. Based on the results obtained, it is concluded that the species has maintenance of reserves of fermentable fuels in the body, so that it is possible to perform anaerobic metabolism and gluconeogenesis, in oxygen deprivation.
The species Phrynops geoffroanus (Testudines: Chelidae), like other species of freshwater turtle, is considered hypoxia-tolerant. These animals have several mechanisms that allow tolerance to the environment with little or no oxygenation. The objective of this study was to evaluate alterations in the blood count and the concentrations of energetic intermediates in tissues blood, hepatic and skeletal and cardiac muscle induced hypoxia. The specimens collected in São José do Rio Preto-SP were divided into two groups: Normóxia, in which the animals had free access to the surface to breathe and Hypoxia, in which a screen was placed below the water level, preventing individuals from reaching the surface to breathe for five hours. There was a difference (p <0.05) between the groups, in which hematocrit, hemoglobin, VGM and HGM levels increased in Hypoxia, hematocrit possibly increased as a consequence of dehydration or increase of VGM, hemoglobin increases in order to rendering oxygen transport more effective to tissues, VGM and HGM emphasize the adaptation of the animal by increasing cell volume and increasing erythrocyte hemoglobin. Regarding metabolism, there were differences in glucose and lactate concentrations in the three tissues, muscle glycogen and plasma amino acids, with the highest concentrations in the hypoxia condition. Hypoxia directly reflects the low glycogen ratio and high glucose rate in the muscles, thus, glycogenolysis is also observed. High concentrations of lactate are also observed, due to the absence of oxygen, causing the muscle cells to perform lactic fermentation for the production of ATP. In order to decrease lactic acidosis, the high lactate content is released into the blood and is directed to the liver cells. It is converted to glucose by gluconeogenesis, which is released into the bloodstream to be made available to the tissues, constituting the Cori cycle. The high concentration of plasma amino acids can occur by protein hydrolysis, being used as substrate of gluconeogenesis or tissue injury. Based on the results obtained, it is concluded that the species has maintenance of reserves of fermentable fuels in the body, so that it is possible to perform anaerobic metabolism and gluconeogenesis, in oxygen deprivation.
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Palavras-chave
Hipóxia, Hematologia, Metabolismo energético, Phrynops geoffroanus, Hypoxia, Hematology, Energetic metabolism