The role of chronic muscle (in)activity on carnosine homeostasis: a study with spinal cord-injured athletes.

To examine the role of chronic (in)activity on muscle carnosine (MCarn) and how chronic (in)activity affects MCarn responses to ß-alanine supplementation in spinal cord-injured athletes, 16 male athletes with paraplegia were randomized (2:1 ratio) to receive ß-alanine (n = 11) or placebo (PL, n = 5). They consumed 6.4 g/day of ß-alanine or PL for 28 days. Muscle biopsies of the active deltoid and the inactive vastus lateralis (VL) were taken before and after supplementation. MCarn in the VL was also compared with the VL of a group of individuals without paraplegia (n = 15). MCarn was quantified in whole muscle and in pools of individual fibers by high-performance liquid chromatography. MCarn was higher in chronically inactive VL vs. well-trained deltoid (32.0 ± 12.0 vs. 20.5 ± 6.1 mmol/kg DM; P = 0.018). MCarn was higher in inactive vs. active VL (32.0 ± 12.0 vs. 21.2 ± 7.5 mmol/kg DM; P = 0.011). In type-I fibers, MCarn was significantly higher in the inactive VL than in the active deltoid (38.3 ± 4.7 vs. 27.3 ± 11.8 mmol/kg DM, P = 0.014). MCarn increased similarly between inactive VL and active deltoid in the ß-alanine group (VL: 68.9 ± 55.1%, P = 0.0002; deltoid: 90.5 ± 51.4%, P < 0.0001), with no changes in the PL group. MCarn content was higher in the inactive VL than in the active deltoid and the active VL, but this is probably a consequence of fiber type shift (type I to type II) that occurs with chronic inactivity. Chronically inactive muscle showed an increase in MCarn after BA supplementation equally to the active muscle, suggesting that carnosine accretion following ß-alanine supplementation is not influenced by muscle inactivity.

Kinetics of Muscle Carnosine Decay after ß-Alanine Supplementation: A 16-wk Washout Study.

PURPOSE: This study aimed to describe the kinetics of carnosine washout in human skeletal muscle over 16 wk. METHODS: Carnosine washout kinetics were studied in 15 young, physically active omnivorous men randomly assigned to take 6.4 g·d-1 of ß-alanine (n = 11) or placebo (n = 4) for 8 wk. Muscle carnosine content (M-Carn) was determined before (PRE), immediately after (POST), and 4, 8, 12, and 16 wk after supplementation. High-intensity exercise tests were performed at these same time points. Linear and exponential models were fitted to the washout data, and the leave-one-out method was used to select the model with the best fit for M-Carn decay data. Repeated-measures correlation analysis was used to assess the association between changes in M-Carn and changes in performance. RESULTS: M-Carn increased from PRE to POST in the ß-alanine group only (+91.1% ± 29.1%; placebo, +0.04% ± 10.1%; P < 0.0001). M-Carn started to decrease after cessation of ß-alanine supplementation and continued to decrease until week 16 (POST4, +59% ± 40%; POST8, +35% ± 39%; POST12, +18% ± 32%; POST16, -3% ± 24% of PRE M-Carn). From week 12 onward, M-Carn was no longer statistically different from PRE. Both linear and exponential models displayed very similar fit and could be used to describe carnosine washout, although the linear model presented a slightly better fit. The decay in M-Carn was mirrored by a similar decay in high-intensity exercise tolerance; M-Carn was moderately and significantly correlated with total mechanical work done (r = 0.505; P = 0.032) and time to exhaustion (r = 0.72; P < 0.001). CONCLUSIONS: Carnosine washout takes 12-16 wk to complete, and it can be described either by linear or exponential curves. Changes in M-Carn seem to be mirrored by changes in high-intensity exercise tolerance. This information can be used to optimize ß-alanine supplementation strategies.

Investigação dos processos biológicos associados à produção endógena de aldeídos reativos / Research on biological processes associated with endogenous production of reactive aldehydes

Os aldeídos são espécies reativas que podem ser produzidos endogenamente por processos como a lipoperoxidação, podendo reagir com lipídios, proteínas e DNA. Diversas evidências apontam para o envolvimento de aldeídos reativos na progressão de patologias como doenças cardiovasculares, arteriosclerose e doenças neurodegenerativas. Uma meta central do CEPIDRedoxoma é estudar a reatividade química de intermediários redox em ambientes biológicos e consequentes mudanças na estrutura e função de biomoléculas, entender como cada intermediário redox reage com biomoléculas específicas e os efeitos resultantes, essenciais para a concepção de biomarcadores e antioxidantes. O nosso grupo estuda os mecanismos de formação, detoxificação e reação com biomoléculas de aldeídos reativos endógenos e exógenos e seu papel em patologias como a esclerose lateral amiotrófica (ALS). Um dos mecanismos de detoxificação desses aldeídos é através da conjugação com a carnosina. Recentemente, foi observado que a suplementação de animais transgênicos ALS SOD G93A com carnosina via oral resultou em retardo da perda de peso e tendência de aumento da sobrevida dos animais. O presente projeto buscou investigar o possível papel da carnosina em animais modelo para ALS. Para isso as modificações em DNA induzidas por aldeídos reativos e a formação de adutos de carnosina-aldeídos foram analisadas através de metodologia HPLC-MS/MS. Assim observamos que ratos suplementados com carnosina apresentaram níveis significativamente menores de proteína carbonilada em músculo e fígado. Em fígadoforam vistos níveis menores de dois adutos de DNA, 8-oxodGuo e1,N2-HO-propanodGuo, em animais suplementados. Em cérebro foram detectados níveis menores de 1, N2-εdGuo. Com relação aos adutos carnosina-aldeídos, foi observado níveis significativamente maiores do aduto CAR-HHE na medula. Com embasamento nos resultados aqui apresentados, sugere-se a utilização de sequestradores de aldeídos como uma estratégia terapêutica em condições fisiopatológicas nas quais ao acúmulo dessas espécies está comprovado

Aldehydes are reactive species that can be produced endogenously by processes such as lipid peroxidation, which can react with lipids, proteins and DNA. Several evidences point to the involvement of reactive aldehydes in the progression of pathologies such as cardiovascular diseases, atherosclerosis and neurodegenerative diseases. A central goal of CEPID-Redoxoma is to study the chemical reactivity of redox intermediates in biological environments and consequent changes in the structure and function of biomolecules, to understand how each redox intermediate reacts with specific biomolecules and the resulting effects, essential for the design of biomarkers and antioxidants. Our group studies the mechanisms of formation, detoxification and reaction with biomolecules of endogenous and exogenous reactive aldehydes and their role in pathologies such as amyotrophic lateral sclerosis (ALS). One of the detoxification mechanisms of these aldehydes is through carnosine conjugation. Recently, we observed that oral carnosine supplementation in transgenic ALS SODG93A animals resulted in delayed weight loss and a tendency to increase the survival of the animals. The present project investigated the potential role of carnosine in animal models for ALS. Thus, reactive aldehydes induced DNA modifications and carnosine aldehyde adducts were analyzed by HPLC-MS/MS. We observed that rats supplemented with carnosine presented significantly lower levels of protein carbonylation in muscle and liver. Lower levels of two DNA adducts, 8-oxodGuo and 1, N2-HO-propanodGuo, were observed in liver of the supplemented animals. Lower levels of 1, N2-εdGuo were detected in the brain. Regarding the carnosine-aldehydeadducts, significantly higher levels of the CAR-HHE adduct were observed in spinal cord. The results presented here suggest the use of aldehyde scavengers as a therapeutic strategy under pathological conditions in which is proven the accumulation of these species