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Background:Diets rich in animal protein and cereal grains and deficient in vegetables and fruits may cause low-grade metabolic acidosis, which may impact exercise and health. We hypothesized that (1) a normal-protein diet with high amount of vegetables and fruits (HV) induces more alkaline acid-base balance compared with a high-protein diet with no vegetables and fruits (HP) and (2) diet composition has a greater impact on acid-base balance in the elderly (ELD).Subjects/methods:In all, 12-15 (adolescents (ADO)), 25-35 (young adults (YAD)) and 60-75 (ELD)-year-old male and female subjects (n=88) followed a 7-day HV and a 7-day HP in a randomized order and at the end performed incremental cycle ergometer tests. We investigated the effect of diet composition and age on capillary (c-pH) and urine pH (u-pH), strong ion difference (SID), partial pressure of carbon dioxide (pCO2) and total concentration of weak acids (Atot). Linear regression analysis was used to examine the contribution of SID, pCO2 and Atot to c-pH.Results:In YAD and ELD, c-pH (P⩽0.038) and u-pH (P<0.001) were higher at rest after HV compared with HP. During cycling, c-pH was higher (P⩽0.034) after HV compared with HP at submaximal workloads in YAD and at 75% of VO2max (maximal oxygen consumption) in ELD. The contribution of SID, pCO2 and Atot to c-pH varied widely. Gender effects or changes in acid-base balance of ADO were not detected.Conclusions:A high intake of vegetables and fruits increases blood and u-pH in YAD and ELD. ELD compared with younger persons may be more sensitive for the diet-induced acid-base changes. [ABSTRACT FROM AUTHOR]

Exercise-induced positive changes in skeletal muscle properties and metabolism decrease the risk for disability, cardiometabolic diseases and mortality. Here, we studied muscle properties and glucose homeostasis in a non-exercise stage in twin pairs with co-twins discordant for physical activity habits for at least 32 years of their adult lives. Isometric knee extension force, MR imaging of midthigh tissue composition and muscle volume, and fasting blood samples were acquired from 16 same-sex (seven monozygotic, nine dizygotic) middle-aged and older twin pairs. The consistently active twins had 20 % higher knee extension forces than their inactive co-twins ( p = 0.006) although the active twins had only 4 % higher midthigh muscle cross-sectional areas ( p = 0.072). These results were similar in intrapair analysis in which only the seven identical twin pairs were included. The ratio between the area of midthigh fat and muscle tissues was significantly lower among the active twins (0.65 vs. 0.48, p = 0.006). The active twins had also lower fasting plasma glucose levels (5.1 vs 5.6 mmol/l, p = 0.041). The area of midthigh intramuscular (extramyocellular) fat was associated with the markers of glucose homeostasis, especially with glycated hemoglobin, and these associations were emphasized by the diabetic and inactive twins. Regular exercise throughout the adult life retains muscle strength and quality but not necessarily mass. The regular use of muscles also prevents from the accumulation of intramuscular fat which might be related to maintained glucose metabolism and, thus, prevention of metabolic disorders. [ABSTRACT FROM AUTHOR]

Background and Objective:Exercise is thought to reduce high-risk body fat, but intervention studies are frequently limited by short follow-ups and observational studies by genetic selection. Therefore, we studied the effects of a physically inactive vs active lifestyle on high-risk (visceral, liver and intramuscular) fat in twin pairs discordant for leisure-time physical activity habits for over 30 years.Design:A longitudinal population-based twin study.Subjects:Sixteen middle-aged (50–74 years) same-sex twin pairs (seven monozygotic (MZ), nine dizygotic (DZ)) with long-term discordance for physical activity habits were comprehensively identified from the Finnish Twin Cohort (TWINACTIVE study). Discordance was initially defined in 1975 and the same co-twin remained significantly more active during the 32-year-long follow-up.Main Outcome Measures:Magnetic resonance imaging-assessed visceral, liver and intramuscular fat.Results:In within-pair analyses carried out after the adult life-long discordance in physical activity habits, the physically inactive co-twins had 50% greater visceral fat area compared with the active co-twins (mean difference 55.5 cm2, 95% confidence interval (CI) 7.0–104.1, P=0.010). The liver fat score was 170% higher (13.2, 95% CI 3.5–22.8, P=0.030) and the intramuscular fat area 54% higher (4.9 cm2, 95% CI 1.9–7.9, P=0.002) among the inactive co-twins. All the trends were similar for MZ and DZ pairs. Peak oxygen uptake was inversely associated with visceral (r=−0.46, P=0.012) and intramuscular fat area (r=−0.48, P=0.028), with similar trends in intrapair difference correlations (r=−0.57, P=0.021 and r=−0.50, P=0.056, respectively). The intrapair difference correlation between visceral and intramuscular fat was also high (r=0.65, P=0.009).Conclusion:Regular physical activity seems to be an important factor in preventing the accumulation of high-risk fat over time, even after controlling for genetic liability and childhood environment. Therefore, the prevention and treatment of obesity should emphasize the role of regular leisure-time physical activity. [ABSTRACT FROM AUTHOR]

We have identified a novel gene product differentially expressed in skeletal muscle in a rat diabetes model induced by streptozotocin. Northern blot analysis showed expression in all studied tissues and a marked down-regulation in insulin-sensitive tissues (skeletal muscle, myocardium) but not in insulin-insensitive brain. cDNA sequence analysis revealed an open reading frame (ORF) of 58 aminoacids, containing one putative transmembrane domain. We designated this protein DAPIT (diabetes-associated protein in insulin-sensitive tissues). Database searches discovered several human, rat, mouse, rabbit, bovine, equine, porcine, Fugu and Xenopus ESTs with significant homology in the ORF. The aminoacid sequence of DAPIT is similar to that of a putative protein of Drosophila melanogaster and to a aAMP-generating peptide isolated from the flesh by Neobellieria bullata. We propose that DAPIT is a novel protein that is highly conserved in vertebrates and insects. [ABSTRACT FROM AUTHOR]

Male rats, aged 17 weeks at the end of experiments, were divided into four groups. Two groups lived in normal cage conditions with or without extra load (20% of the body weight) and two groups were trained by running with or without extra load for 8 weeks. Oxidation rates of succinate, glutamate + malate, palmitoylcarnitine, and pyruvate, and the activities of lactate dehydrogenase, citrate synthase, isocitrate dehydrogenase and cytochrome oxidase were measured in homogenates of the right ventricle and in those of the subendocardial and subepicardial layers of the left ventricle. Oxidation rates of succinate and palmitoylcarnitine tended to be higher in the subendocardium than in the subepicardium of sedentary control animals (p<0.1 and p<0.05, respectively). Transmural differences of succinate and palmitoylcarnitine oxidation rates were even more clear after running training (p<0.01 and p<0.05, respectively), after carrying extra load (p<0.001 and p<0.001, respectively) and after training carrying extra load (p<0.001 and p<0.05, respectively). Training also enhanced pyruvate oxidation rate in the subendocardium. Oxidation rates of all substrates were lower in the right ventricle than in the left ventricle. In control animals there were no regional differences in the myocardial enzyme activities and the training- or extra-load-induced changes were modest compared with the changes in the oxidation rates. The most significant change was the training-induced enhancement in the lactate dehydrogenase activity of the subendocardium (p<0.001 vs subepicardium). These results show greater subendocardial than subepicardial oxidation rates of certain substrates in the normal heart. These results also suggest that the myocardium adapts to increased work by increasing the subendocardial oxidation rate of some but not all substrates, indicating further that there may be qualitative mitochondrial differences in the different regions of the heart. [ABSTRACT FROM AUTHOR]

Regional glucose uptake in perfused hearts, and the activities of several glycolytic enzymes contributing to the glucose metabolism in perfused and nonperfused hearts were studied in male and female rats after 8-9 weeks of swimming training. The left ventricular glucose uptake showed a transmural gradient in the sedentary animals, the subendocardial uptake being 30% and 12% higher than that of the subepicardial layer in the males and females, respectively. Swimming exercise abolished the left ventricular glucose uptake gradient in male rats, and in female rats an opposite gradient was found, the subepicardial uptake being 23% higher than the subendocardial uptake. The activities of phosphofructokinase and 3-phosphoglyceraldehyde dehydrogenase also showed transmural gradients in the left ventricles. Training did not abolish these gradients. Training-induced changes in the activities of phosphofructokinase, 3-phosphoglyceraldehyde dehydrogenase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, citrate synthase, and malate dehydrogenase were found in certain sites of the myocardium. Perfusion of isolated hearts for 50 min with insulin-containing Krebs-Ringer buffer especially affected the activities of phosphofructokinase, lactate dehydrogenase, and citrate synthase, increasing these activities in the left ventricles and decreasing them in the atria. These results indicate that there are regional differences between male and female rats in the cardiac glucose uptake rate after swimming training. [ABSTRACT FROM AUTHOR]

The effect of 10 weeks of running training and termination of training on the regional distribution of cardiac glucose uptake and protein synthesis were studied in isolated perfused hearts in male rats. The left ventricular glucose uptake in hearts from sedentary rats was 1.87±0.14 μmol/min per g protein (mean ± SE), being about 30% higher in the subendocardial than in the subepicardial layer (p<0.05). The gradient of left ventricular glucose uptake was similar to the controls in the rats retired from training, but was absent in the trained animals. The altered transmural glucose uptake probably reflects differences in the adaptive response of various myocardial muscle layers to a long-term intermittent increase in cardiac work load. Phenylalanine incorporation was evenly distributed through the left ventricle in all the groups, but was lowered in the left and right ventricles of the trained rats. Phenylalanine incorporation returned to the control level 5 weeks after the cessation of training. [ABSTRACT FROM AUTHOR]

We studied the effects of running-training, heavy exercise and termination of training on the heart weight, the ratio heart to body weight and the cardiac muscle activities of actomyosin ATPase, citrate synthase, succinate dehydrogenase, cytochrome c oxidase, malate dehydrogenase, adenylate kinase and β-glucuronidase with adult male NMRI-mice. Stable hypertrophy (6-7%), estimated by the ratio heart or ventricle weight to body weight, was achieved by 28 exercises and it was dependent on the running speed (20 vs. 25 m x min). The withdrawal of training for 5-61 days did not permanently decrease the heart weight or the heart to body weight ratio to the level of sedentary controls. The activity of enzymes of energy metabolism or actomyosin. ATPase were not affected by training, heavy exercise or terminated training. β-glucuronidase activity slightly (20-25%) increased in the trained animals and remained at a higher level during the period of terminated training. The results suggest that the capacity for aerobic metabolism of normal mice heart is sufficient to meet the enhanced demands for ATP imposed by running-training and that the heart enlargement occurs in equal proportions with the enzymatic potential of the cardiac tissue. [ABSTRACT FROM AUTHOR]

Increased levels of mRNA transcribed from the ob gene in adipose tissue of obese/hyperin-sulinaemic Zucker ( fa/fa) rats were detectable as early as 3 weeks after birth and continued to rise there after in parallel with body weight and serum insulin. mRNA levels of two other fat-specific genes (ARL4, FST44) were unaltered. In C57BL/KsJ db/db mice, ob mRNA levels also increased in parallel with body weight and serum insulin, and remained elevated in older animals when insulin levels decreased. In heterozygous control animals ( db/ +; fa/Fa), mRNA levels were comparable with those in the homozygous controls. In normal Sprague Dawley rats, the ob mRNA increased continuously, but more slowly than in Zucker rats, in parallel with body weight and insulin levels, and reached 15 times higher levels in the heaviest rats (400 g) studied. In Sprague Dawley rats made diabetic by an injection of streptozotocin, ob mRNA levels were reduced by approximately 50 % after 24 h. A 24-h fasting period reduced the ob mRNA by 50 % in lean Sprague Dawley and Fa/Fa, but not in obese Zucker fa/fa rats, although insulin levels were reduced in both groups. These data indicate that ob mRNA levels increase in both normal and obese rodents in parallel with age, body weight and serum insulin, reflecting an early (Zucker rats, db-mice) or slowly developing (Sprague Dawley rats) resistance to leptin and insulin. This increase does not appear to be mediated by the recently described rapid regulation of ob mRNA by insulin, but seems to be due to a different, long-term control mechanism which signals the size of the fat depots. [ABSTRACT FROM AUTHOR]

Rats were exercised for 6 h by swimming. Phenylalanine incorporation into myocardial proteins was increased when 2 h had elapsed after the termination of exercise. Cyclic GMP concentration did not change during the experiment, which indicates that cyclic GMP does not act directly as a trigger of myocardial protein synthesis in volume overload. [ABSTRACT FROM AUTHOR]

Mice and rats were adjusted to daily treadmill training programs, which were heavy enough to increase the oxidative capacity of skeletal muscles. Endurance training did not affect the activities of catalase and glutathione peroxidase and the concentration of vitamin E in the lungs of mice and rats. Thus increased ventilation and oxygen utilization induced by exercise training do not modify lung antioxidants, in contrast to hyperoxia and hypoxia. [ABSTRACT FROM AUTHOR]

Endurance training over 3, 10 or 20 days increased the activity of prolyl 4-hydroxylase (PH) in the left ventricle of mice. No increase was observed in the weight of the left ventricle, in galactosylhydroxylysyl glucosyltransferase activity or in hydroxyproline concentration. The increase in PH suggests that the synthesis of collagen increases during physiological adaptation of the heart to endurance exercise without changes in the ventricle weight or its total collagen content. [ABSTRACT FROM AUTHOR]

Physical exercise increased the activities of arylsulphatase, cathepsin D and β-glucuronidase in mouse skeletal muscle but not in cardiac muscle. Exercise-induced lysosomal response was more prominent in young adult than in senescent mice. The lipofuscin content of cardiac and skeletal muscles increased markedly during ageing and was also found to increase slightly after exertion in young mice, but not in senescent ones. [ABSTRACT FROM AUTHOR]