The aim of this study was to investigate the effect of lactatemia elevation and glycemia reduction on strenuous swimming performance in fasted rats. Three rats were placed in a swimming tank at the same time. The first rat was removed immediately (control group) and the remaining ones were submitted to a strenuous swimming session. After the second rat was exhausted (Exh group), the third one was immediately removed from the water (Exe group). According to the period of time required for exhaustion, the rats were divided into four groups: low performance (3–7 min), low-intermediary performance (8–12 min), high-intermediary performance (13–17 min), and high performance (18–22 min). All rats were removed from the swimming tanks and immediately killed by decapitation for blood collection or anesthetized for liver perfusion experiments. Blood glucose, lactate, and pyruvate concentrations, blood lactate/pyruvate ratio, and liver lactate uptake and its conversion to glucose were evaluated. Exhaustion in low and low-intermediary performance were better associated with higher lactate/pyruvate ratio. On the other hand, exhaustion in high-intermediary and high performance was better associated with hypoglycemia. Lactate uptake and glucose production from lactate in livers from the Exe and Exh groups were maintained. We concluded that there is a time sequence in the participation of lactate/pyruvate ratio and hypoglycemia in performance during an acute strenuous swimming section in fasted rats. The liver had an important participation in preventing hyperlactatemia and hypoglycemia during swimming through lactate uptake and its conversion to glucose.

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The non-enzymatic antioxidant system protects blood components from oxidative damage and/or injury. Herein, plasma nonenzymatic antioxidant capacity after acute strenuous swimming exercise (Exe) and exercise until exhaustion (Exh) was measured in rats. The experiments were carried out in never exposed (Nex) and pre-exposed (Pex) groups. The Nex group did not undergo any previous training before the acute strenuous swimming test and the Pex group was submitted to daily swimming for 10 min in the first week and 15 min per day in the second week before testing. Plasma glucose, lactate, and pyruvate were measured and plasma total protein sulfhydryl groups (thiol), trolox equivalent antioxidant capacity (TEAC), ferric reducing ability of plasma (FRAP), and total radical-trapping antioxidant parameter (TRAP) levels were evaluated. There were marked increases in plasma lactate concentrations (

We developed a pre-clinical model in which to evaluate the impact of orally administered carbohydrates on postprandial blood glucose levels. For this purpose, we compared the effects of different carbohydrates with well-established glycemic indexes. We orally administered (gavage) increasing amounts (0.2, 0.4, 0.6, 0.8, and 1.0 g/kg) of sucrose and lactose to rats which had been fasted for 6 h or 15 h, respectively. In part of the experiments we administered frutose (gavagem). Three different models were compared for measuring postprandial blood glucose levels: a) evaluation of interstitial glucose concentrations by using a real time continuous glucose monitoring system; b) evaluation of glucose levels in blood obtained from the rat tail; c) evaluation of serum glucose levels in blood collected after decapitation. Our results showed that blood obtained from the tails of 15-h fasted rats was the best model in which to evaluate the effect of carbohydrates on postprandial blood glucose levels.

RESUMO:As fibras alimentares vêm despertando interesse de especialistas das áreas de nutrição e saúde em geral. Elas contribuem para a redução do risco de desenvolvimento de doenças cardiovasculares, além de ajudar no processo de perda de peso, principalmente quando seu consumo é associado à atividade física. Entretanto, existem poucos estudos associando o uso de fibras solúveis à uma dieta hipercalórica e ao exercício físico. Assim, o objetivo desse estudo foi investigar os efeitos das fibras solúveis sobre a aorta torácica e perfil lipídico de ratos machos wistar sedentários e treinados submetidos à dieta de cafeteria. Os parâmetros morfométrico e estereológico foram: espessura íntima-média e densidade de volume do músculo liso e do colágeno e o perfil lipídico foi, então, determinado. Não foram observadas alterações na espessura da parede vascular, densidade de volume do músculo liso e colágeno. No entanto, o perfil lipídico apresentou-se alterado com o uso da dieta de cafeteria. A fibra alimentar associada ao treinamento aeróbio e a uma dieta balanceada apresentou resultado eficaz, não alterando a morfologia do vaso. PALAVRAS-CHAVE:Aorta; Dieta; Fibras na Dieta; Obesidade. EFFECTS OF SUPPLEMENTATION BY SOLUBLE FIBERS, CAFETERIA DIET AND PHYSICAL EXERCISE ON RATS´ THORACIC AORTAABSTRACT: Food fibers have recently been in the limelight of nutrition and health experts. They reduce the development of cardiovascular diseases and help in the process of loss weight especially when their intake is associated with physical activity. However, few studies are extant on the use of soluble fibers associated to a hypercalorie diet and physical exercise. Current analysis deals with the effects of soluble fibers on the thoracic aorta and lipid profile of sedentary and trained male Wistar rats subjected to a cafeteria diet. Morphometric and stereological parameters comprised mid thickness and density of the volume of the smooth muscle and collagen, and lipid profile. No changes were reported on the thickness of the vascular wall, density of volume of the smooth muscle and collagen. However, lipid profile was modified due to the cafeteria diet. Food fiber associated with aerobic training and with a balanced diet provided an efficacious result with no alteration in the vase´s morphology.

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We investigated whether oral lactate could prevent seizures and deaths in mice with severe hypoglycemia induced by a high dose of insulin. For this purpose, mice were fasted for 15 h and then given an intraperitoneal injection of regular insulin (5.0 U/kg or 10.0 U/kg). Immediately after insulin injection, the mice received an oral dose of saline (control), glucose (5.5 mmol/kg), or lactate (18.0 mmol/kg). Glucose and lactate levels were measured in the blood and brain before and after the seizures began. Glucose and lactate delayed (p < 0.05) the onset of seizures associated with severe insulin-induced hypoglycemia. Elevated (p < 0.05) brain levels of lactate were associated with an absence of seizures in mice that received glucose or lactate, suggesting that lactate could prevent convulsions associated with severe insulin-induced hypoglycemia. However, the same oral dose of lactate that delayed the onset of convulsions also increased the mortality rate. In contrast, diazepam (3.0 mg/kg) prevented seizures and markedly decreased the frequency of death during severe insulin-induced hypoglycemia. The results demonstrated that in contrast to oral glucose, oral lactate intensifies insulin toxicity.

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