Resumo: A anemia falciforme (Hb SS), caracterizada por estados de inflamação crônica e eventos de agressão isquêmica e reperfusão pode causar danos oxidativos às macromoléculas biológicas. Os genes epistáticos e os haplótipos do gene da globina βS são possíveis moduladores de variabilidade fenotípica na Hb SS. A melatonina pode atenuar o estresse oxidativo e abrandar a morbidade. O objetivo deste foi analisar a influência de talassemia alfa (-α3.7), haplótipos do gene βS e melatonina na capacidade antioxidante total e expressão fenotípica, em indivíduos com Hb SS e Hb AS. Para avaliar o nível de melatonina sérica foram selecionadas 15 amostras de pacientes com Hb SS e 24 com Hb AA da região noroeste do estado do Paraná (NOPR). A triagem das hemoglobinas foram realizadas por métodos eletroforéticos e cromatográfico, e a caracterização genotípica da Hb S por meio de PCR- RFLP e PCR-AE. As espécies reativas de ácido tiobarbitúrico (TBARS), e a capacidade antioxidante total em equivalência ao Trolox (TEAC) foram determinadas por meio da espectrofotometria. A melatonina foi estimada por meio de HPLC. O estado redox foi analisado selecionando amostras de 68 indivíduos com Hb SS, 53 com Hb AS e 149 com Hb AA, das regiões sul e sudeste do Brasil. Para analisar a influência dos genes epistáticos sobre a TEAC, melatonina e expressão fenotípica, foram selecionadas 17 amostras com Hb SS, 30 com Hb AS, e 30 com Hb AA, da NOPR. O critério para elegebilidade foi ser não fumantes não gestantes, não etilistas e estar na fase estável para os indivíduos com HbSS. Os haplótipos do gene βS e a talassemia -α3.7 foram identificados por meio de PCR-RFLP e PCR multiplex, respectivamente. Os níveis séricos de melatonina apresentaram-se reduzidos nos indivíduos com Hb SS (P<0,001), e os TBARS e TEAC elevados quando comparados a grupo controle (P<0,001 e P<0,01 respectivamente)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Sickle cell disease (Hb SS), characterized by chronic inflammation and ischemic damage episodes and reperfusion, comprises excessive production of free radicals which can cause oxidative damage to biologic macromolecules. The epistatic genes and the polymorphism of the βS globin gene region are possible modulators of phenotypical variability of sickle cell disease in Hb SS. Melatonin can diminish both the oxidative stress and morbidity. The objective of this study was to analyze the influence of -α-3.7 thalassemia and from βS gene haplotypes on total anti-oxidant capacity, melatonin serum levels and phenotypical expression in individuals with Hb SS and Hb AS. To evaluate melatonin serum level 15 samples with HbSS and 24 with Hb AA from the northwest region of Paraná state (NOPR). The hemoglobin screenings were performed by electrophoretic and chromatographic methods and genotypic characterization of Hb S by PCR- RFLP and PCR-AE. The concentrations of thiobarbituric acid reactive substances (TBARS), used as markers of oxidative stress and total antioxidant capacity in equivalence to Trolox (TEAC), were determined by spectrophotometry. Melatonin was estimated by HPLC. The redox state was analyzed through selecting 68 individuals with Hb SS, 53 with Hb AS and 149 with Hb AA from Brazil's south and southeast regions. To analyze the influence of epistatic genes on TEAC, melatonin and phenotypical expression, there were selected 17 samples with Hb SS, 30 with Hb AS, and 30 with Hb AA from NOPR. The βS gene haplotypes and -α-3.7 thalassemia were identified through RFLP-PCR and multiplex PCR, respectively. The melatonin serum levels appeared significantly reduced in individuals with Hb SS (P<0.001); and the TBARS and TEAC appeared significantly increased when compared to the control group (P<0.001 and P<0.01, respectively). The correlation between TBARS and TEAC (r=0.51; P=0.04)... (Complete abstract click electronic access below) / Orientador: Claudia Regina Bonini Domingos / Coorientador: Eduardo Alves de Almeida / Banca: Hermione Elly Melara de Campos Bicudo / Banca: Paulo César Naoum / Banca: Isaac Lima da Silva Filho / Banca: Octavio Ricci Junior / Doutor

La drépanocytose est la maladie génétique la plus répandue au monde. Elle est caractérisée par la synthèse d’une hémoglobine anormale S (HbS) et associée à une altération des processus de distribution d’oxygène. Bien que ces anomalies puissent impacter le muscle strié squelettique, ce tissu n’a que très rarement été étudié. L’objectif de ce travail de thèse était de décrire les réponses fonctionnelles et énergétiques du muscle à l’exercice aigu, à l’ischémie – reperfusion et à l’entraînement en endurance dans un modèle de souris drépanocytaires, et d’identifier les mécanismes responsables des échanges de protons entre le muscle et le sang.Des souris drépanocytaires sédentaires et entraînées ont été soumises à des protocoles standardisés de repos – stimulation – récupération et repos – ischémie – reperfusion pendant lesquels la force et le métabolisme énergétique (par spectroscopie de résonance magnétique du phosphore 31) étaient mesurés. Des souris hétérozygotes pour le transporteur de monocarboxylate 1 (MCT1) ont également été soumises au protocole de stimulation. Des analyses in vitro du métabolisme énergétique et des mécanismes de régulation du pH ont également été réalisées.Ce travail a permis de démontrer que les réponses fonctionnelles et énergétiques à l’exercice musculaire et l’ischémie - reperfusion étaient affectées par la présence d’HbS et que l’entraînement en endurance permettait d’améliorer une partie de ces anomalies. Nous avons également observé que MCT1 était responsable de l’entrée des protons dans la cellule au repos, mais peu actif pendant l’exercice. / Sickle cell disease (SCD) is the most frequent inherited disorder in the world. It is characterized by the synthesis of an abnormal hemoglobin S (HbS) and associated with impairments in oxygen delivery processes. If these abnormalities could impact skeletal muscle, this tissue has been rarely investigated. The aim of this thesis was to investigate muscular function and energetics in response to acute exercise, ischemia – reperfusion and endurance training in a mouse model of SCD, as well as identify the mechanisms involved in proton exchanges between muscle and blood.Sedentary and trained SCD mice were submitted to protocols of rest – stimulation – recovery and rest – ischemia – reperfusion during which muscular force and energetics (by magnetic resonance spectroscopy of phosphorus 31) were measured. Monocarboxylate transporter 1 (MCT1) haploinsufficient mice were also submitted to the stimulation protocol. Several muscles were sampled and permitted to analyze in vitro enzyme activities, content of proteins involved in pH regulation and some markers of oxidative stress.This thesis demonstrated that muscular function and energetics were impaired in SCD mice in response to both exercise and ischemia – reperfusion and that endurance training could alleviate some of these abnormalities, particularly acting on oxidative processes. We have also observed that MCT1 is involved in proton uptake by myocytes at rest, but its action is less important during exercise.