Purpose: There is a large interindividual variation in the parasympathetic adaptation induced by aerobic exercise training, which may be partially attributed to genetic polymorphisms. Therefore, we investigated the association among three polymorphisms in the endothelial nitric oxide gene (−786T>C, 4b4a, and 894G>T), analyzed individually and as haplotypes, and the parasympathetic adaptation induced by exercise training. Methods: Eighty healthy males, age 20-35 yr, were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis, and haplotypes were inferred using the software PHASE 2.1. Autonomic modulation (i.e., HR variability and spontaneous baroreflex sensitivity) and peak oxygen consumption (V˙O2peak) were measured before and after training (running, moderate to severe intensity, three times per week, 60 min·day−1, during 18 wk). Results: Training increased V˙O2peak (P < 0.05) and decreased mean arterial pressure (P < 0.05) in the whole sample. Subjects with the −786C polymorphic allele had a significant reduction in baroreflex sensitivity after training (change: wild type (−786TT) = 2% ± 89% vs polymorphic (−786TC/CC) = −28% ± 60%, median ± quartile range, P = 0.03), and parasympathetic modulation was marginally reduced in subjects with the 894T polymorphic allele (change: wild type (894GG) = 8% ± 67% vs polymorphic (894GT/TT) = −18% ± 59%, median ± quartile range, P = 0.06). Furthermore, parasympathetic modulation percent change was different between the haplotypes containing wild-type alleles (−786T/4b/894G) and polymorphic alleles at positions −786 and 894 (−786C/4b/894T) (−6% ± 56% vs −41% ± 50%, median ± quartile range, P = 0.04). Conclusions: The polymorphic allele at position −786 and the haplotype containing polymorphic alleles at positions −786 and 894 in the endothelial nitric oxide gene were associated with decreased parasympathetic modulation after exercise training.
The influence of Glu298Asp endothelial nitric oxide synthase (eNOS) polymorphism in exercise-induced reflex muscle vasodilatation is unknown. We hypothesized that nonexercising forearm blood flow (FBF) responses during handgrip isometric exercise would be attenuated in individuals carrying the Asp298 allele. In addition, these responses would be mediated by reduced eNOS function and NO-mediated vasodilatation or sympathetic vasoconstriction. From 287 volunteers previously genotyped, we selected 33 healthy individuals to represent three genotypes: Glu/Glu [n = 15, age 43 +/- 3 yr, body mass index (BMI) 22.9 +/- 0.3 kg/m(2)], Glu/Asp (n = 9, age 41 +/- 3 yr, BMI 23.7 +/- 1.0 kg/m(2)), and Asp/Asp (n = 9, age 40 +/- 4 yr, BMI 23.5 +/- 0.9 kg/m(2)). Heart rate (HR), mean blood pressure (MBP), and FBF (plethysmography) were recorded for 3 min at baseline and 3 min during isometric handgrip exercise. Baseline HR, MBP, FBF, and forearm vascular conductance (FVC) were similar among genotypes. FVC responses to exercise were significantly lower in Asp/Asp when compared with Glu/Asp and Glu/Glu (Delta = 0.07 +/- 0.14 vs. 0.64 +/- 0.20 and 0.57 +/- 0.09 units, respectively; P = 0.002). Further studies showed that intra-arterial infusion of NG-monomethyl-L-arginine (L-NMMA) did not change FVC responses to exercise in Asp/Asp, but significantly reduced FVC in Glu/Glu (Delta = 0.79 +/- 0.14 vs. 0.14 +/- 0.09 units). Thus the differences between Glu/Glu and Asp/Asp were no longer observed (P = 0.62). l-NMMA + phentolamine increased similarly FVC responses to exercise in Glu/Glu and Asp/Asp (P = 0.43). MBP and muscle sympathetic nerve activity increased significant and similarly throughout experimental protocols in Glu/Glu and Asp/Asp. Individuals who are homozygous for the Asp298 allele of the eNOS enzyme have attenuated nonexercising muscle vasodilatation in response to exercise. This genotype difference is due to reduced eNOS function and NO-mediated vasodilatation, but not sympathetic vasoconstriction.
O oxido nitrico (NO), primariamente identificado como um fator relaxante derivado do endotelio, e um radical livre atuante na sinalizacao de diferentes processos biologicos. A identificacao das isoformas das sintases do NO (NOS) e a subsequente caracterizacao dos mecanismos de ativacao celulares das enzimas possibilitaram tanto a compreensao de parte das interacoes fisiologicas como a compreensao de parte dos mecanismos de doenca, na qual o NO esta envolvido. A isoforma endotelial da NOS (eNOS), expressa principalmente no endotelio vascular, desempenha importante papel na regulacao da reatividade vascular e no desenvolvimento e na progressao da aterosclerose. Esta revisao tem o proposito de contextualizar o leitor sobre a estrutura da eNOS e seus mecanismos de ativacao celular. Tendo em vista os avancos da biologia molecular, trataremos ainda dos conhecidos mecanismos de regulacao da expressao genica e do papel de variantes no codigo genetico da eNOS associados a fenotipos cardiovasculares. Embora se reconheca a importância do NO como molecula ateroprotetora, nossa atencao estara voltada a revisao de literatura envolvendo NO e sua participacao na modulacao do fenotipo de vasodilatacao muscular.
Aim: The purpose of this study was to identify a PBMC gene expression signature in response to endurance training. We also aimed to identify transcripts associated with changes in peak oxygen uptake (VO 2peak ). Methods: Healthy untrained policemen recruits (n=13; 25 ± 3 yrs; BMI 27.0 ± 2.8 kg∙m ‐2 ) were selected. VO 2peak (cardiopulmonary exercise test) and total RNA were obtained before and after 18 weeks of running endurance training (3 times/wk; 60min), for whole‐genome expression analysis (GeneChip ® Human Gene 1.0 ST). Results: Training induced changes (Δ) in VO 2peak (0.27±0.28 l∙min ‐1 , P =0.09) and a differential regulation of 211 transcripts ( P <0.05; fold change>1.3). Baseline expression levels of 98 transcripts were strongly correlated with absolute ΔVO 2peak ( r >0.75; P <0.01). Differentially regulated transcripts were mostly represented in immune response of heat shock proteins and cytokines (HSPA1A, IL‐1), cell cycle regulation of differentiation and post‐translational modification processes (Histone H1, PLK1, SUMO‐1) and growth factors (EGR1, GH) activation and signalling. Conclusions: We describe a transcriptional map regulated by endurance training, ocurring in easily accessed PBMCs. Future research will focus on establishing transcriptional markers of trainability. Grant Funding Source : Supported by FAPESP #2005/59740‐7; CNPq #482863/2011‐0
A bacteriocina bovicina HC5, sintetizada por Streptococcus equinus HC5, é capaz de inibir o crescimento de diversos microrganismos patogênicos e deteriorantes de alimentos. Além disso, o peptídeo é termotolerante, resistente ao pH ácido e apresenta baixa toxicidade in vivo, o que confere vantagens para sua aplicação industrial. Obter maior rendimento de produção e efetiva recuperação é um dos principais gargalos para viabilizar o uso da bovicina HC5. Neste projeto, S. equinus HC5 foi submetido a diferentes temperaturas de incubação para avaliar os efeitos do estresse térmico no crescimento deste microrganismo. Posteriormente, foi utilizado a técnica de evolução adaptativa em laboratório (EAL) por estresse térmico com o objetivo de selecionar linhagens de S. equinus HC5 com maior produção de bovicina HC5. Foi observado, neste estudo, que a temperatura ótima de crescimento do S. equinus HC5 é 42 °C e que temperaturas maiores que 49 °C inibem completamente o crescimento da cultura. O processo de EAL em batelada foi mantido por 400 gerações (100 dias) em temperaturas de 47 °C e 48 °C. Oito linhagens com fenótipos distintos foram selecionadas, sendo que destas, duas apresentaram produção aumentada de bovicina HC5 entre 26% e 140% (P < 0,05). A linhagem com a maior produção da bacteriocina apresentou expressão diferencial dos genes biossintéticos da bovicina HC5, e foi observado maiores níveis de expressão do gene que codifica para o peptídeo precursor (bvcA) (P < 0,05). Além disso, as linhagens adaptadas apresentaram modificação na composição dos ácidos graxos de membrana, com aumento da concentração de ácidos graxos saturados (P < 0,05). A linhagem obtida ao final do processo de evolução apresentou maior resistência ao estresse térmico, demonstrando maior taxa de crescimento específico (µ = 1,33 ± 0,02 h -1) e biomassa (DO600nm = 4,03 ± 0,06) a 48 °C em relação à linhagem selvagem (µ = 0,98 ± 0,04 h - e DO600nm = 1,96 ± 0,12) (P < 0,05). Os resultados desta pesquisa indicam que a EAL é uma estratégia eficaz para a seleção de linhagens de S. equinus HC5 com produção aumentada da bacteriocina bovicina HC5.Palavras-chave: Bacteriocinas. Bactérias lácticas. Estresse térmico.