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The study of Ellsworth et al. (Br J Haematol, 2024) demonstrated the usefulness of oxygen gradient ektacytometry technique to better identify the physiological parameters that could increase the risk of sickling of red blood cells (RBCs) from sickle cell trait (SCT) carriers. Oxygen gradient ektacytometry combined with pH and osmolality modulations could help in identifying SCT carriers at risk for kidney disorders or exercise-related complications. Other factors than the percentages of haemoglobin S are probably involved in the propensity of RBCs from SCT carriers to sickle during deoxygenation. Commentary on: Ellsworth et al. Hypertonicity and/or acidosis induce marked rheological changes under hypoxic conditions in sickle trait red blood cells. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19669.
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Patients with sickle cell disease (SCD) often experience painful vaso-occlusive crises and chronic haemolytic anaemia, as well as various acute and chronic complications, such as leg ulcers. Leg ulcers are characterized by their unpredictability, debilitating pain and prolonged healing process. The pathophysiology of SCD leg ulcers is not well defined. Known risk factors include male gender, poor social conditions, malnutrition and a lack of compression therapy when oedema occurs. Leg ulcers typically start with spontaneous pain, followed by induration, hyperpigmentation, blister formation and destruction of the epidermis. SCD is characterized by chronic haemolysis, increased oxidative stress and decreased nitric oxide bioavailability, which promote ischaemia and inflammation and consequently impair vascular function in the skin. This cutaneous vasculopathy, coupled with venostasis around the ankle, creates an ideal environment for local vaso-occlusive crises, which can result in the development of leg ulcers that resemble arterial ulcers. Following the development of the ulcer, healing is hindered as a result of factors commonly observed in venous ulceration, including venous insufficiency, oedema and impaired angiogenesis. All of these factors are modulated by genetic factors. However, our current understanding of these genetic factors remains limited and does not yet enable us to accurately predict ulceration susceptibility.
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Anemia Falciforme , Úlcera da Perna , Humanos , Anemia Falciforme/complicações , Anemia Falciforme/fisiopatologia , Úlcera da Perna/etiologia , Úlcera da Perna/fisiopatologia , Fatores de Risco , MasculinoRESUMO
Sickle cell disease (SCD) is a genetic disorder characterized by complex pathophysiological mechanisms leading to vaso-occlusive crisis, chronic pain, chronic hemolytic anemia, and vascular complications, which require considerations for exercise and physical activity. This review aims to elucidate the safety, potential benefits, and recommendations regarding exercise and training in individuals with SCD. SCD patients are characterized by decreased exercise capacity and tolerance. Acute intense exercise may be accompanied by biological changes (acidosis, increased oxidative stress, and dehydration) that could increase the risk of red blood cell sickling and acute clinical complications. However, recent findings suggest that controlled exercise training is safe and well tolerated by SCD patients and could confer benefits in disease management. Regular endurance exercises of submaximal intensity or exercise interventions incorporating resistance training have been shown to improve cardiorespiratory and muscle function in SCD, which may improve quality of life. Recommendations for exercise prescription in SCD should be based on accurate clinical and functional evaluations, taking into account disease phenotype and cardiorespiratory status at rest and in response to exercise. Exercise programs should include gradual progression, incorporating adequate warm-up, cool-down, and hydration strategies. Exercise training represents promising therapeutic strategy in the management of SCD. It is now time to move through the investigation of long-term biological, physiological, and clinical effects of regular physical activity in SCD patients.
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We investigated highlanders, permanently living at an altitude of 5100 m and compared Chronic Mountain Sickness (CMS) patients with control volunteers. While we found differences in systemic parameters such as blood oxygen content, hematocrit, hemoglobin concentration, and blood viscosity, the mechanical and rheological properties of single red blood cells did not differ between the two investigated groups.
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Doença da Altitude , Eritrócitos , Humanos , Doença da Altitude/sangue , Masculino , Adulto , Doença Crônica , Feminino , Hematócrito , Pessoa de Meia-Idade , Viscosidade Sanguínea , Hemoglobinas/análise , Altitude , Transfusão de Eritrócitos , Oxigênio/sangueRESUMO
On-chip study of blood flow has emerged as a powerful tool to assess the contribution of each component of blood to its overall function. Blood has indeed many functions, from gas and nutrient transport to immune response and thermal regulation. Red blood cells play a central role therein, in particular through their specific mechanical properties, which directly influence pressure regulation, oxygen perfusion, or platelet and white cell segregation toward endothelial walls. As the bloom of in-vitro studies has led to the apparition of various storage and sample preparation protocols, we address the question of the robustness of the results involving cell mechanical behavior against this diversity. The effects of three conservation media (EDTA, citrate, and glucose-albumin-sodium-phosphate) and storage time on the red blood cell mechanical behavior are assessed under different flow conditions: cell deformability by ektacytometry, shape recovery of cells flowing out of a microfluidic constriction, and cell-flipping dynamics under shear flow. The impact of buffer solutions (phosphate-buffered saline and density-matched suspension using iodixanol/Optiprep) are also studied by investigating individual cell-flipping dynamics, relative viscosity of cell suspensions, and cell structuration under Poiseuille flow. Our results reveal that storing blood samples up to 7 days after withdrawal and suspending them in adequate density-matched buffer solutions has, in most experiments, a moderate effect on the overall mechanical response, with a possible rapid evolution in the first 3 days after sample collection.
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Deformação Eritrocítica , Eritrócitos , Deformação Eritrocítica/fisiologia , Eritrócitos/fisiologia , Viscosidade Sanguínea , Viscosidade , MicrofluídicaRESUMO
Haemoglobin S polymerization in the red blood cells (RBCs) of individuals with sickle cell anaemia (SCA) can cause RBC sickling and cellular alterations. Piezo1 is a mechanosensitive protein that modulates intracellular calcium (Ca2+ ) influx, and its activation has been associated with increased RBC surface membrane phosphatidylserine (PS) exposure. Hypothesizing that Piezo1 activation, and ensuing Gárdos channel activity, alter sickle RBC properties, RBCs from patients with SCA were incubated with the Piezo1 agonist, Yoda1 (0.1-10 µM). Oxygen-gradient ektacytometry and membrane potential measurement showed that Piezo1 activation significantly decreased sickle RBC deformability, augmented sickling propensity, and triggered pronounced membrane hyperpolarization, in association with Gárdos channel activation and Ca2+ influx. Yoda1 induced Ca2+ -dependent adhesion of sickle RBCs to laminin, in microfluidic assays, mediated by increased BCAM binding affinity. Furthermore, RBCs from SCA patients that were homo-/heterozygous for the rs59446030 gain-of-function Piezo1 variant demonstrated enhanced sickling under deoxygenation and increased PS exposure. Thus, Piezo1 stimulation decreases sickle RBC deformability, and increases the propensities of these cells to sickle upon deoxygenation and adhere to laminin. Results support a role of Piezo1 in some of the RBC properties that contribute to SCA vaso-occlusion, indicating that Piezo1 may represent a potential therapeutic target molecule for this disease.
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Anemia Falciforme , Cálcio , Humanos , Cálcio/metabolismo , Laminina/metabolismo , Eritrócitos/metabolismo , Eritrócitos Anormais/metabolismoRESUMO
Abnormal retention of mitochondria in mature red blood cells (RBC) has been recently reported in sickle cell anemia (SCA) but their functionality and their role in the pathophysiology of SCA remain unknown. The presence of mitochondria within RBC was determined by flow cytometry in 61 SCA patients and ten healthy donors. Patients were classified according to the percentage of mature RBC with mitochondria contained in the whole RBC population: low (0-4%), moderate (>4% and <8%), or high level (>8%). RBC rheological, hematological, senescence and oxidative stress markers were compared between the three groups. RBC senescence and oxidative stress markers were also compared between mature RBC containing mitochondria and those without. The functionality of residual mitochondria in sickle RBC was measured by high-resolution respirometry assay and showed detectable mitochondrial oxygen consumption in sickle mature RBC but not in healthy RBC. Increased levels of mitochondrial reactive oxygen species were observed in mature sickle RBC when incubated with Antimycin A versus without. In addition, mature RBC retaining mitochondria exhibited greater levels of reactive oxygen species compared to RBC without mitochondria, as well as greater Ca2+, lower CD47 and greater phosphatidylserine exposure. Hematocrit and RBC deformability were lower, and the propensity of RBC to sickle under deoxygenation was higher, in the SCA group with a high percentage of mitochondria retention in mature RBC. This study showed the presence of functional mitochondria in mature sickle RBC, which could favor RBC sickling and accelerate RBC senescence, leading to increased cellular fragility and hemolysis.
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Anemia Falciforme , Hemólise , Humanos , Espécies Reativas de Oxigênio , Eritrócitos , Estresse Oxidativo , MitocôndriasRESUMO
THC triggers a pronounced entry of Ca2+ , which may be deleterious, into sickle cell red blood cells via activation of the TRPV2 channel.
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Anemia Falciforme , Dronabinol , Humanos , Dronabinol/efeitos adversos , Eritrócitos , Anemia Falciforme/tratamento farmacológicoRESUMO
OBJECTIVES: European Crohn's Colitis Organization (ECCO) and the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidelines recommend the early use of anti-tumor necrosis factor (TNF) biologicals in pediatric Crohn disease (CD) patients with positive predictors for poor outcome. The objective of the present study was to compare early "Top-Down" use of adalimumab (ADA) immunomodulator/biologics-naive patients to conventional "Step-Up" management. METHODS: One hundred and twenty consecutive patients with a confirmed diagnosis of CD and treated with ADA between 2008 and 2019 were included and allocated to the ADA-Top Down (n = 59) or ADA-Step Up group (n = 61). The primary endpoint was prolonged steroid-/enteral nutrition-free clinical remission at 24 months, defined by a weighted Pediatric Crohn's Disease Activity Index (wPCDAI) < 12.5. Clinical and biological data were collected at 12 and 24 months. RESULTS: At start of ADA, disease activity was comparable between the ADA-Top Down group and the ADA-Step Up group (wPCDAI = 31 ± 16 vs 31.3 ± 15.2, respectively, P = 0.84). At 24 months, the remission rate was significantly higher in the ADA-Top Down group (73% vs 51%, P < 0.01). After propensity score, the Top-Down strategy is still more effective than the Step-Up strategy in maintaining remission at 24 months [hazard ratio (HR) = 0.36, 95% CI (0.15-0.87), P = 0.02]. Patients in the ADA-Top Down group were mainly on monotherapy compared to patients in the ADA-Step Up group (53/55 vs 28/55 respectively, P < 0.001). Serum levels of ADA were higher in the ADA-Top Down group than in the ADA-Step Up group (12.8 ± 4.3 vs 10.4 ± 3.9 µg/mL, respectively, P < 0.01). There were no serious adverse events. CONCLUSIONS: Early use of ADA appears to be more effective in maintaining relapse-free remission at 2 years, while using it as monotherapy. These findings further favor the recommendation of early anti-TNF use in high-risk CD patients.
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Adalimumab , Doença de Crohn , Criança , Humanos , Adalimumab/uso terapêutico , Doença de Crohn/tratamento farmacológico , Seguimentos , Infliximab/uso terapêutico , Indução de Remissão , Resultado do Tratamento , Inibidores do Fator de Necrose Tumoral/uso terapêuticoRESUMO
Patients with sickle cell disease (SCD) have poorly deformable red blood cells (RBC) that may impede blood flow into microcirculation. Very few studies have been able to directly visualize microcirculation in humans with SCD. Sublingual video microscopy was performed in eight healthy (HbAA genotype) and four sickle cell individuals (HbSS genotype). Their hematocrit, blood viscosity, red blood cell deformability, and aggregation were individually determined through blood sample collections. Their microcirculation morphology (vessel density and diameter) and microcirculation hemodynamics (local velocity, local viscosity, and local red blood cell deformability) were investigated. The De Backer score was higher (15.9 mm-1) in HbSS individuals compared to HbAA individuals (11.1 mm-1). RBC deformability, derived from their local hemodynamic condition, was lower in HbSS individuals compared to HbAA individuals for vessels < 20 µm. Despite the presence of more rigid RBCs in HbSS individuals, their lower hematocrit caused their viscosity to be lower in microcirculation compared to that of HbAA individuals. The shear stress for all the vessel diameters was not different between HbSS and HbAA individuals. The local velocity and shear rates tended to be higher in HbSS individuals than in HbAA individuals, notably so in the smallest vessels, which could limit RBC entrapment into microcirculation. Our study offered a novel approach to studying the pathophysiological mechanisms of SCD with new biological/physiological markers that could be useful for characterizing the disease activity.
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Anemia Falciforme , Soalho Bucal , Humanos , Microcirculação/fisiologia , Hemodinâmica , Eritrócitos/fisiologia , Hemoglobina Falciforme , ReologiaRESUMO
We have recently reported that hypobaric hypoxia (HH) reduces plasma volume (PV) in men by decreasing total circulating plasma protein (TCPP). Here, we investigated whether this applies to women and whether an inflammatory response and/or endothelial glycocalyx shedding could facilitate the TCCP reduction. We further investigated whether acute HH induces a short-lived diuretic response that was overlooked in our recent study, where only 24-h urine volumes were evaluated. In a strictly controlled crossover protocol, 12 women underwent two 4-day sojourns in a hypobaric chamber: one in normoxia (NX) and one in HH equivalent to 3,500-m altitude. PV, urine output, TCPP, and markers for inflammation and glycocalyx shedding were repeatedly measured. Total body water (TBW) was determined pre- and postsojourns by deuterium dilution. PV was reduced after 12 h of HH and thereafter remained 230-330 mL lower than in NX (P < 0.0001). Urine flow was 45% higher in HH than in NX throughout the first 6 h (P = 0.01) but lower during the second half of the first day (P < 0.001). Twenty-four-hour urine volumes (P ≥ 0.37) and TBW (P ≥ 0.14) were not different between the sojourns. TCPP was lower in HH than in NX at the same time points as PV (P < 0.001), but inflammatory or glycocalyx shedding markers were not consistently increased. As in men, and despite initially increased diuresis, HH-induced PV contraction in women is driven by a loss of TCPP and ensuing fluid redistribution, rather than by fluid loss. The mechanism underlying the TCPP reduction remains unclear but does not seem to involve inflammation or glycocalyx shedding.NEW & NOTEWORTHY This study is the first to investigate the mechanisms underlying plasma volume (PV) contraction in response to hypoxia in women while strictly controlling for confounders. PV contraction in women has a similar time course and magnitude as in men and is driven by the same mechanism, namely, oncotically driven redistribution rather than loss of fluid. We further report that hypoxia facilitates an increase in diuresis, that is, however, short-lived and of little relevance for PV regulation.
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Hipóxia , Volume Plasmático , Masculino , Humanos , Feminino , Volume Plasmático/fisiologia , Altitude , Diurese , InflamaçãoRESUMO
The aim of this study was to (1) analyze blood viscosity, red blood cell (RBC) deformability, and aggregation in hospitalized patients with Coronavirus disease 19 (COVID-19); (2) test the associations between impaired blood rheology and blood coagulation; and (3) test the associations between impaired blood rheology and several indicators of clinical severity. A total of 172 patients with COVID-19, hospitalized in COVID-unit of the Internal Medicine Department (Lyon, France) participated in this study between January and May 2021. Clinical parameters were collected for each patient. Routine hematological/biochemical parameters, blood viscosity, RBC deformability and aggregation, and RBC senescence markers were measured on the first day of hospitalization. A control group of 38 healthy individuals was constituted to compare the blood rheological and RBC profile. Rotational thromboelastography was performed in 76 patients to study clot formation dynamics. Our study demonstrated that patients with COVID-19 had increased blood viscosity despite lower hematocrit than healthy individuals, as well as increased RBC aggregation. In-vitro experiments demonstrated a strong contribution of plasma fibrinogen in this RBC hyper-aggregation. RBC aggregation correlated positively with clot firmness, negatively with clot formation time, and positively with the length of hospitalization. Patients with oxygen supplementation had higher RBC aggregation and blood viscosity than those without, and patients with pulmonary lesions had higher RBC aggregation and enhanced coagulation than those without. This study is the first to demonstrate blood hyper-viscosity and RBC hyper-aggregation in a large cohort of patients with COVID-19 and describe associations with enhanced coagulation and clinical outcomes.
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Viscosidade Sanguínea , COVID-19/sangue , Agregação Eritrocítica , Eritrócitos/patologia , Adulto , Idoso , Coagulação Sanguínea , COVID-19/diagnóstico , COVID-19/patologia , Deformação Eritrocítica , Humanos , Pessoa de Meia-Idade , SARS-CoV-2/isolamento & purificaçãoRESUMO
OBJECTIVES: The first ECCO-ESPGHAN guidelines for the medical management of pediatric Crohn disease (CD) were published in 2014. Whether their implementation, and the consequent increased use of an upfront anti-tumor necrosis factor therapy, have changed the course of the disease has not been investigated yet. We aimed at comparing the evolution of pediatric CD patients diagnosed and treated before and after 2014. METHODS: Single-center retrospective study including all children diagnosed with CD from January 2010 to December 2018. Patients diagnosed between 2010 and 2014 (group 1) were compared to those diagnosed after 2014 (group 2). For each patient, at baseline and every 6-month, number of relapses, the occurrence of complication, therapy received and biological parameters were noted, as well as any endoscopic or radiologic evaluation. RESULTS: One hundred and fifty-four patients were included in the analysis, 78 (51%) diagnosed after 2014. The cumulative probability of a relapse-free and surgery-free course was significantly higher for patients treated according to the guidelines (log rank hazard ratio [HR] = 1,818, P = 0.003 and HR = 3,15, 95% confidence interval, P = 0.04, respectively). Mucosal healing rate was significantly higher among patients of group 2 at 1 and 2âyears (P = 0.04 and P = 0.05, respectively), while no significant difference was observed for transmural healing rates, as well as for the risk of complications. CONCLUSIONS: The implementation of the 2014 CD guidelines appears to have a significant impact on disease outcomes, with a significantly lower risk for relapse and surgery, while no effect could be observed on the risk of developing complications.
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Doença de Crohn , Criança , Doença de Crohn/diagnóstico , Humanos , Infliximab/uso terapêutico , Recidiva , Estudos Retrospectivos , Fator de Necrose Tumoral alfaRESUMO
The present study tested the impact of α-thalassaemia on oxygen gradient ektacytometry in sickle cell anaemia (SCA). Three SCA groups were compared: (i) no α-thalassaemia (four α-genes, n = 62), (ii) silent α-thalassaemia (three α-genes, n = 35) and (iii) homozygous α-thalassaemia (two α-genes, n = 12). Red blood cell (RBC) deformability measured in normoxia was not different between the three groups. The lowest RBC deformability reached at low oxygen partial pressure (pO2 ) was greater and the pO2 at which RBC started to sickle was lower in the two α-genes group compared to the other groups. Our present study showed an effect of α-thalassaemia on oxygen gradient ektacytometry in SCA.
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Anemia Falciforme/sangue , Deformação Eritrocítica , Oxigênio/sangue , Talassemia alfa/sangue , Adolescente , Adulto , Anemia Falciforme/complicações , Anemia Falciforme/genética , Criança , Pré-Escolar , Índices de Eritrócitos , Genótipo , Humanos , Pressão Osmótica , Resistência ao Cisalhamento , Adulto Jovem , alfa-Globinas/genética , Talassemia alfa/complicações , Talassemia alfa/genética , Globinas beta/genéticaRESUMO
Inflammation and oxidative stress play a key role in the pathophysiology of sickle cell disease (SCD). However, the potential influence of different sickle genotypes, or hydroxyurea (HU) treatment, on these factors remains poorly documented. The present study compared several plasma markers of inflammation and oxidative stress, as well as microvascular function, between patients with sickle SC disease (HbSC, n = 19) and patients with sickle cell anemia (HbSS) under hydroxyurea (HU) treatment (n = 16), or not (n = 13). Hemorheological parameters and levels of inflammatory (IL-6, IL-8, IFN-γ, MCP-1, MIP-1ß, TNF-α) and oxidative stress (AOPP, MDA, MPO) markers were determined. Peripheral microcirculatory cutaneous blood flow and immediate microvascular response to local heat were evaluated using laser Doppler flowmetry. Oxidative stress and inflammation were lower in HbSC patients and HbSS patients under HU therapy compared to HbSS patients not treated with HU. Blood viscosity was higher in HbSC than in HbSS patients treated with or not with HU. Vasodilation response of the cutaneous microcirculation to heat stress was higher in HbSS patients receiving HU treatment. Our results clearly established that both sickle cell genotype and HU treatment modulate inflammation and oxidative stress.
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Anemia Falciforme , Viscosidade Sanguínea/efeitos dos fármacos , Hidroxiureia/administração & dosagem , Microcirculação/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/tratamento farmacológico , Anemia Falciforme/fisiopatologia , Biomarcadores/sangue , Feminino , Humanos , Inflamação/sangue , Inflamação/tratamento farmacológico , Inflamação/fisiopatologia , Masculino , Pessoa de Meia-IdadeRESUMO
This study aimed to investigate the changes in blood viscosity, pulmonary hemodynamics, nitric oxide (NO) production, and maximal oxygen uptake (VËO2max) during a maximal incremental test conducted in normoxia and during exposure to moderate altitude (2,400 m) in athletes exhibiting exercise-induced hypoxemia at sea level (EIH). Nine endurance athletes with EIH and eight without EIH (NEIH) performed a maximal incremental test under three conditions: sea level, 1 day after arrival in hypoxia, and 5 days after arrival in hypoxia (H5) at 2,400 m. Gas exchange and oxygen peripheral saturation (SpO2) were continuously monitored. Cardiac output, pulmonary arterial pressure, and total pulmonary vascular resistance were assessed by echocardiography. Venous blood was sampled before and 3 min after exercise cessation to analyze blood viscosity and NO end-products. At sea level, athletes with EIH exhibited an increase in blood viscosity and NO levels during exercise while NEIH athletes showed no change. Pulmonary hemodynamics and aerobic performance were not different between the two groups. No between-group differences in blood viscosity, pulmonary hemodynamics, and VËO2max were found at 1 day after arrival in hypoxia. At H5, lower total pulmonary vascular resistance and greater NO concentration were reported in response to exercise in EIH compared with NEIH athletes. EIH athletes had greater cardiac output and lower SpO2 at maximal exercise in H5, but no between-group differences occurred regarding blood viscosity and VËO2max. The pulmonary vascular response observed at H5 in EIH athletes may be involved in the greater cardiac output of EIH group and counterbalanced the drop in SpO2 in order to achieve similar VËO2max than NEIH athletes.
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Altitude , Exercício Físico/efeitos adversos , Hemodinâmica , Hipóxia/fisiopatologia , Saturação de Oxigênio , Atletas , Viscosidade Sanguínea , Humanos , Óxido Nítrico , Oxigênio , Consumo de Oxigênio , ReologiaRESUMO
Here we describe the effects of a controlled, 30 min, high-intensity cycling test on blood rheology and the metabolic profiles of red blood cells (RBCs) and plasma from well-trained males. RBCs demonstrated decreased deformability and trended toward increased generation of microparticles after the test. Meanwhile, metabolomics and lipidomics highlighted oxidative stress and activation of membrane lipid remodeling mechanisms in order to cope with altered properties of circulation resulting from physical exertion during the cycling test. Of note, intermediates from coenzyme A (CoA) synthesis for conjugation to fatty acyl chains, in parallel with reversible conversion of carnitine and acylcarnitines, emerged as metabolites that significantly correlate with RBC deformability and the generation of microparticles during exercise. Taken together, we propose that RBC membrane remodeling and repair plays an active role in the physiologic response to exercise by altering RBC properties.
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Eritrócitos/metabolismo , Exercício Físico/fisiologia , Lipídeos de Membrana/sangue , Esforço Físico/genética , Adulto , Contagem de Eritrócitos , Deformação Eritrocítica/genética , Humanos , Lipidômica , Masculino , Metabolômica , Consumo de Oxigênio , Esforço Físico/fisiologiaRESUMO
PURPOSE: Blood rheology is a key determinant of blood flow and tissue perfusion. There are still large discrepancies regarding the effects of an acute running exercise on blood rheological properties and red blood cell (RBC) physiology. We investigated the effect of a 10 km running trial on markers of blood rheology and RBC physiology in endurance trained athletes. METHODS: Blood was sampled before and after the exercise to measure lactate and glucose, hematological and hemorheological parameters (blood viscosity, RBC deformability, and aggregation), eryptosis markers (phosphatidylserine and CD47 exposure, RBC reactive oxygen species), RBC-derived microparticles (RBC-MPs), and RBC electrophysiological activity. Weight was measured before and after exercise. Peripheral oxygen saturation and heart rate were monitored before and during the trial. RESULTS: Blood lactate and glucose levels increased after exercise and subjects significantly lost weight. All athletes experienced a significant fall in oxygen saturation. Mean corpuscular volume (MCV) was increased from 95.1 ± 3.2 to 96.0 ± 3.3 and mean corpuscular hemoglobin concentration (MCHC) decreased after exercise suggesting a slight RBC rehydration. Exercise increased RBC deformability from 0.344 ± 0.04 to 0.378 ± 0.07, decreased RBC aggregates strength and blood viscosity, while hematocrit (Hct) remained unaffected. While RBC electrophysiological recording suggested a modulation in RBC calcium content and/or chloride conductance, eryptosis markers and RBC-MPs were not modified by the exercise. CONCLUSION: A 10 km acute running exercise had no effect on RBC senescence and membrane blebbing. In contrast, this exercise increased RBC deformability, probably through rehydration process which resulted in a decrease in blood viscosity.
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Eriptose , Frequência Cardíaca , Hemorreologia , Condicionamento Físico Humano/métodos , Corrida/fisiologia , Adulto , Atletas , Glicemia/metabolismo , Micropartículas Derivadas de Células/metabolismo , Eritrócitos/metabolismo , Feminino , Humanos , Ácido Láctico/sangue , Masculino , Consumo de Oxigênio , Condicionamento Físico Humano/efeitos adversosRESUMO
Blood rheology is a key determinant of tissue perfusion at rest and during exercise. The present study investigated the effects of race distance on hematological, blood rheological, and red blood cell (RBC) senescence parameters. Eleven runners participated in the Martigny-Combes à Chamonix 40 km race (MCC, elevation gain: 2300 m) and 12 others in the Ultra-Trail du Mont Blanc (UTMB, 171 km, elevation gain: 10,000 m). Blood samples were collected before and after the races. After the UTMB, the percentage of RBC phosphatidylserine (PS) exposure was not affected while RBC CD235a levels decreased and RBC-derived microparticles increased. In contrast, after the MCC, RBC PS exposure increased, while RBC CD235a and RBC-derived microparticles levels were not affected. The free hemoglobin and hemolysis rate did not change during the races. RBC aggregation and blood viscosity at moderate shear rates increased after the MCC. RBC deformability, blood viscosity at a high shear rate, and hematocrit decreased after the UTMB but not after the MCC. Our results indicate that blood rheology behavior is different between a 40 km and a 171 km mountain race. The low blood viscosity after the ultra-marathon might facilitate blood flow to the muscles and optimize aerobic performance.