Lipoprotein-lipase activity of human skeletal-muscle and adipose tissue after intensive physical exercise.

Seven young, healthy subjects performed bicycle exercise with a working load leading to exhaustion after one hour of work. The tests were done in the afternoon in the fed state. The serum insulin concentrations decreased from 22 to 4 mU/l and plasma glucagon increased from 241 to 340 pg/l already after 30 min of work. The level of adipose tissue lipoprotein lipase activity (LPLA) did not fall as had been expected, but increased. The skeletal muscle LPLA was unchanged. The results indicate that during the first hour of heavy exercise the heparin-releasable LPLA in tissues is not influenced by the work induced changes in serum hormone levels.     

Lipoprotein lipase activity in the skeletal muscle during physical exercise in dogs

Changes in lipoportein lipase activity/LPLA/ in the quadriceps femoris muscle were followed in ten dogs during 3-hour treadmill exercise and 2-hour post-exercise recovery period. During the first hour of exercise muscle LPLA steeply increased. Subsequently the enzyme activity tended to plateau. After exercise LPLA decreased to the pre-exercise value within 1 hour. It is concluded that exercise increases the ability of skeletal muscles to remove triglycerides from the circulation.     

Changes in muscle lipoprotein lipase activity during exercise in dogs fed on a mixed fat-rich meal

Skeletal muscle lipoprotein lipase activity LPLA was compared in dogs performing prolonged treadmill exercise after 20–22 h fasting or 4 h following mixed fat-rich meal ingestion. In the fasting state muscle LPLA increased progressively during 2 h exercise. In fed dogs the resting value of the muscle LPLA was considerably lower than that in the fasting state, and no increase in the enzyme activity occurred during physical effort. The inhibition of the muscle LPLA by the meal ingestion can be attributed to the persisting effects of increased plasma insulin and/or FFA concentrations, found at the beginning of exercise.Supported by the Polish Academy of Sciences within the project 10.4.     

Lipoprotein lipase activity and intramuscular triglyceride stores after long-term high-fat and high-carbohydrate diets in physically trained men

Men with regular physical training habits voluntarily increased their dietary fat intake from 43 to 54% of energy (E%) for four weeks. This was followed by a low-fat (29 E%), high-carbohydrate diet for another four weeks. During the high-fat diet period, the muscle lipoprotein lipase activity (LPLA) increased from 59 +/- 8 to 106 +/- 12 mU/g (mean +/- SE) (P less than 0.05). After the high-carbohydrate diet, LPLA was 57 +/- 16 mU/g, and unchanged relative to the pre-trial value. The triglyceride content in m. vastus lateralis increased from 30 +/- 4 to 47 +/- 9 mmol/kg d.w. (P less than 0.05; mean +/- SE) following the high-fat diet and to 41 +/- 8 following the high-carbohydrate diet. Neither of the diets affected the serum triglyceride and insulin concentrations, nor glucose, glycerol, beta-hydroxybutyrate, citrate and lactate levels in the blood. Nor did they alter enzyme activities in muscle used as markers for the oxidative (citrate synthase, beta-hydroxy-acyl CoA dehydrogenase) and glycolytic (glyceraldehyde phosphate dehydrogenase, lactate dehydrogenase) capacity. It is concluded that one month's adaptation to a high-fat diet results in increased muscle-LPL activity indicating a higher capacity for uptake of fatty acids from circulating serum triglycerides into the muscle cell in association with a greater capacity for triglyceride storage in the muscle. Under these conditions serum triglycerides were not decreased despite the increased muscle LPLA, and serum insulin variations could not explain the change in muscle LPLA.(ABSTRACT TRUNCATED AT 250 WORDS)     

两种不同运动方式血乳酸浓度对血管内溶血的影响

目的 观察运动中血乳酸浓度的变化对血管内溶血的影响。方法 受试者为大学体育系学生10名健康男子，通过功率自行车，进行渐增负荷和稳定负荷两种不同运动。最大负荷运动从1kp的强度开始，每1分钟增加0．25kp，直到力竭为止。稳定负荷运动为最大运动负荷时的最大心率的50％（50％HRmax)，进行30分钟的稳定负荷运动。在运动前、运动结束后即刻及运动后恢复期30分钟，由肘静脉采血。血液中指标有血乳酸、Ht和Hp。结果 最大负荷运动结束后血乳酸浓度明显高于运动前水平，运动结束1小时后血乳酸浓度恢复到运动前水平，可是在稳定负荷运动结束后却没有变化。此外，最大负荷运动结束后即刻Hp浓度下降，但没有显著性差异。结论 虽运动中血乳酸引起血pH下降，但并未引起溶血发生。     

不同运动强度干预2型糖尿病模型大鼠的骨密度变化

BACKGROUND:More than 50% of patients with diabetes are accompanied by osteoporosis. Exercise is the main method to treat diabetes, but whether it has an impact on diabetes osteoporosis is unclear. OBJECTIVE:To analyze the different exercise intensities and changes in bone mineral density in type 2 diabetic rat models. METHODS:Forty rats were randomly divided into model group and low-, medium- and high-intensity exercise groups. All rats received intraperitoneal injection of streptozotocin to establish models of type 2 diabetes. Rats in the low-, medium- and high-intensity exercise groups did treadmill training at 10, 20, 30 m/min, 1 hour per day, 6 days as a cycle. They had a rest for 1 day after each cycle, for 8 consecutive cycles. Rats in the model group did not do any exercise. RESULTS AND CONCLUSION:Compared with the model group, the weight of rats was decreased; blood glucose levels were reduced; osteocalcin and serum calcium levels and biomechanical indexes of femur increased; serum phosphorus and alkaline phosphatase decreased in the low-, medium- and high-intensity exercise groups. Bone mineral density increased in the medium- and high-intensity exercise groups. These findings confirmed that different exercise intensities have a certain influence on bone mineral density and bone metabolism in type 2 diabetic rat models. When using a method of treating movement, proper physical exercise can increase serum osteocalcin content, improve bone metabolism, prevent diabetic osteoporosis, and have a high clinical value.     

Urinary excretion of electrolytes during prolonged physical activity in normal man

Summary Nine normal young male students were studied during 2 days of relative rest, during 2 days of physical training and again during the succeeding 2 days of relative rest.Twenty-four hour urine collections showed that sodium and potassium excretion were lower during the exercise days, while urinary aldosterone excretion was increased. No differences in the 24-h urinary excretion of creatinine, calcium, and magnesium were found between the resting and exercise days.Hemoglobin concentration, hematocrit and red cell counts were decreased at 14 h and 42 h after exercise; these findings together with the increased serum bilirubin concentration could result from hemolysis.Plasma renin activity, angiotensin II and aldosterone concentration were increased 14 h after exercise but returned to baseline 42 h after exercise.Our data shows that one should take into account previous exercise when interpreting results of certain of these tests.     

Circulating VEGF As a Biological Marker in Patients with Rheumatoid Arthritis? Preanalytical and Biological Variability in Healthy Persons and in Patients

Background: Soluble vascular endothelial growth factor (VEGF) is a promising biomarker in monitoring rheumatoid arthritis (RA), but studies of pre-analytical and biologic variability are few. Methods: VEGF was measured by ELISA methods in serum and plasma from healthy persons and RA patients. Pre-analytical factors were investigated. A reference interval for VEGF was established in serum and plasma from 306 healthy persons. Diurnal, day-to-day, week-to-week, long-term variability, and impact of exercise were evaluated. Results: Delayed processing time, room temperature, low centrifugal force and contamination of plasma with cellular elements lead to significant increases in VEGF levels, whereas storage for up to 2 years at −80°C or up to 10 freeze/thaw cycles did not affect VEGF levels. Serum VEGF levels were 7–10 fold higher than plasma VEGF levels. Reference intervals for VEGF (plasma: 45 pg/ml (range: non-detectable to 352); serum: 328 pg/ml (53–1791)) were independent of gender and age. Short- and long-term biologic variability included diurnal variation (sampling should take place after 7 AM) and impact of exercise (increased VEGF immediately after bicycling normalised within 1 hour). Conclusions: Pre-analytical factors and biologic variability including diurnal variation and impact of exercise should be accounted for in future studies that include circulating VEGF as a biological marker.     

Human adipose tissue blood flow during prolonged exercise II

Subcutaneous and perirenal adipose tissue blood flows (ATBF) were measured by the¹³³Xe washout method before, during and after 4 h exercise on a bicycle ergometer. The load corresponded to about 50% of max (i.e. about 1.7l/min). Subcutaneous and perirenal ATBF increased at an average to 3–400 and 700% of their initial control values respectively. In six of nine measuring sites ATBF remained increased in the hour following work. During work plasma glycerol concentrations increased 8 fold. The core temperature increased 0.9°C, skin temperature did not change significantly. During passive elevation of body temperature (core temperature +1.5°C; skin temperature +3°C) neither subcutaneous ATBF nor plasma glycerol concentrations changed significantly. It is concluded that the increase in subcutaneous ATBF during exercise is not a reaction to increased body temperature.     

Serum vaspin concentrations are decreased after exercise-induced oxidative stress

Elevated visceral adipose tissue-derived serpin (vaspin) serum concentrations are associated with impaired insulin sensitivity, but increase unexpectedly after long-term physical training. We therefore investigated the effect of an acute exercise bout and the effects of vitamin supplementation on chronic exercise effect and on serum vaspin concentrations. We measured serum vaspin and thiobarbituric acid-reactive substances (TBARS) concentrations in 80 individuals before and after a 1-hour acute exercise bout and independently in 40 healthy young men who were randomly assigned to either antioxidant (vitamin C (1,000 mg/day) and vitamin E (400 IU/day)) or to no supplementation after a standardized 4-week physical training program as a post hoc analysis. Serum vaspin concentrations significantly decreased after acute physical exercise as well as after 4 weeks of training in individuals without antioxidants. Changes in vaspin serum concentration correlate with increased TBARS serum concentrations both in response to a 1-hour exercise bout (r = -0.42, p < 0.01) and to the 4-week training (r = -0.31, p < 0.05). Interestingly, supplementation with antioxidants rather increased circulating vaspin levels in response to 4 weeks of exercise. In conclusion, vaspin serum concentrations are decreased by exercise-induced oxidative stress, but not by exercise-associated improvement in insulin sensitivity.     

热应激预处理对离心运动大鼠骨骼肌自由基代谢的影响

背景：研究表明热预处理能够提高肌肉抗损伤的能力,但具体的机制尚不清楚。 目的：观察热应激预处理对离心运动大鼠骨骼肌超氧化物歧化酶活性及丙二醛含量的影响。 方法：雄性Wistar大鼠随机分为对照组、离心运动组、预热应激+离心运动组。热应激温度为43 ℃,时间约35 min。采用-16°下坡跑台跑做大负荷间歇性离心运动,跑速为26.8 m/min,运动5 min,间歇1 min,共进行10组。分别于运动前1 h、运动后1,24,48 h取大鼠腓肠肌,采用硫代巴比妥酸法测定大鼠丙二醛含量,黄嘌呤氧化酶法测定超氧化物歧化酶活性。 结果与结论：与对照组比较,离心运动组大鼠腓肠肌丙二醛含量显著增高(P < 0.05),并随运动后时间的延长逐渐升高,超氧化物歧化酶活性随运动后时间的延长显著降低(P < 0.05)。与离心运动组比较,预热应激+离心运动组大鼠腓肠肌超氧化物歧化酶活性显著增高(P < 0.05),丙二醛含量显著降低(P < 0.05)。说明热应激预处理可增强骨骼肌超氧化物歧化酶活性,降低丙二醛含量,对离心运动损伤有保护作用。     

Ethanol reduces myoglobin release during isokinetic muscle exercise

Changes in serum myoglobin concentrations were studied in 12 healthy males performing a standardized isokinetic 2-min exercise test. The test was performed on three separate occasions: in the habitual state, during moderate ethanol intoxication and one day after ethanol intake. Although the performed muscle work, maximal heart rate, and blood lactate levels did not differ between the three test occasions, the serum myoglobin increments after exercise were significantly reduced (p less than 0.05) in the ethanol-intoxicated state and also 10-15 hours after ethanol intake. The reduction of the exercise-induced myoglobin increment was not explained by increased elimination of the protein. The mechanism, therefore, is likely to be a reduction of myoglobin release from skeletal muscle due to an ethanol-induced alteration of the muscle cell membrane, possibly by means of adenylate cyclase activation.     

The response of oxygen consumption,body temperature,blood substrates and serum enzymes to intermittent heavy work performed over twenty-four hours

Summary The response of blood substrates and serum enzymes to repeated exercise over 24 h were studied in four trained males, aged from 25–33 years, with a O₂ max averaging 59.2 ml/kg/min. Exercise consisted of treadmill running for 6 min once per hour at approximately 95% O₂ max. Water was permitted ad libitum throughout the experiment and glucose during the final 12 h. Venous blood samples were obtained prior to and following every fourth work bout.Measurement of O₂ during the final 30 s of the first run was 4.11 l·min^–1 and no significant deviation from the value was observed in any of the succeeding runs. Resting plasma free fatty acids increased approximately threefold over the duration of the experiment while blood glucose decreased from the fourth to the sixteenth work hour. A small increase in blood glucose occurred early in the glucose ingestion period, however, this did not persist and glucose levels showed progressive declines for the remainder of the experiment. Blood lactate and pyruvate values were elevated following each exercise bout. Repeated heavy work also elicited elevations in two serum enzymes, creatine phosphokinase and glutamic oxaloacetic transaminase. The declining respiratory exchange ratios suggest that over an extended period of time when progressive carbohydrate depletion is occurring and plasma levels of free fatty acids are elevated, fat oxidation can play an increasingly significant role in energy liberation during near maximal work.This study was supported by a grant from the Muscular Dystrophy Association of Canada and the National Research Council.     

No effect of growth hormone administration on substrate oxidation during exercise in young, lean men

The purpose of this study was to examine the effects of increased fat availability induced by growth hormone (GH) administration on the oxidative metabolism during exercise. Seven well-trained males (age 25 ± 2 years (mean ± s.e.m. ); peak oxygen consumption     : 62 ± 1 ml min⁻¹ kg⁻¹ (completed four randomised trials: 120 min bicycling at 55%     4 h after receiving either 7.5 IU (2.5 mg) GH or placebo (Plc), and during rest after receiving either GH or Plc. In all studies a standardized meal was given 2 h after GH or Plc injection. GH administration resulted in an ∼60-fold increase in serum GH concentration at rest ( P < 0.0001) and during exercise ( P < 0.0001). The increase in serum GH was followed by an increase in circulating glycerol at rest (8%, P < 0.0001). When combined with exercise the increase in plasma glycerol was more pronounced (GH: 716% of baseline versus Plc: 328%, P < 0.0001). However, this increase in fat mobilization did not increase fat oxidation during exercise (indirect calorimetry). In conclusion, GH administration combined with aerobic exercise increased lipolytic parameters substantially more than exercise alone, but did not further augment whole body fat oxidation.     

Serum levels of glucose,insulin, and C-peptide during long-term D-ribose administration in man

Summary D-ribose was given orally and/or intravenously to nine healthy subjects at doses ranging from 83.3 to 222.2 mg/kg per hour for at least four hours. The serum ribose level increased in a dose-dependent manner to maximum concentrations of 75 to 85 mg/dl. The serum glucose level decreased after the beginning of continuous ribose administration and was reduced as long as ribose was being administered. The oral or intravenous administration of 166.7 mg/kg per hour of ribose resulted in a 25% decrease in serum glucose. Higher intravenous doses of ribose did not provoke a further decrease in serum glucose concentration. Oral administration of 166.7 mg/kg per hour led to an increase in serum insulin concentrations from a mean of 8.4 (range 6.4–11.5) to 10.4 (range 6.3–15.4) U/ml (p<0.05). In contrast, intravenous administration did not change serum insulin concentrations significantly. The serum c-peptide concentration remained unchanged regardless of treatment. We conclude that the variations in plasma insulin concentrations do not account for the observed decrease in mean serum glucose concentrations accompanying D-ribose administration.This paper was supported by a grant from the Friedrich-Baur-Stiftung, Federal Republic of Germany     

Diffusion of rifampicin into spongy and compact bone tissue during total hip prosthesis operation

Sixty eight patients received either an oral single dose of 300 mg (or 300 mg/12 h), or an oral single dose of 600 mg (or 600 mg/24 h) of rifampicin. In every case samples of serum and bone were collected 3 h, 12 h, and 24 h after the last oral dose. Rifampicin levels measured at 3 h and 12 h in cortical bone samples increased significantly with the dose of the drug. The only dose which determines activity in cortical bone at the 3rd hour was the dose of 600 mg. When the dose was increased from 300 mg/12 h to 600 mg/24 h the ratio spongious bone/serum increased from 0.19 to 0.41 at 3d h and from 0.24 to 0.29 at the 12th hour; the ratio cortical bone serum was 0.20 at the 3rd hour after a dose of 600 mg. In any case tissue levels varied in a parallel direction to serum levels and were superior in spongious bone to the MIC of S. aureus sensitive strains until 12 h after the 600 mg dose. According to these results, it appears that the best dose for treating S. aureus bone infection seems to be 600 mg/12 h.     

A controlled randomized study on the effect of long-term physical exercise on the metabolic control in type 2 diabetic patients

The effects of 4 months' physical exercise on the metabolic control in non-insulin-dependent diabetes were studied in 25 patients divided randomly into exercise (n = 13) and control (n = 12) groups. In the exercise group glycosylated hemoglobin A1 fell from 9.6-8.6% (p less than 0.01) and the 2 hour plasma glucose in oral glucose tolerance test decreased from 19.7-16.5 mmol/l (p less than 0.01). The mean fall in fasting plasma glucose from 11.8-10.5 mmol/l was not statistically significant. The responses of plasma insulin and C-peptide to oral glucose increased significantly during the exercise period. However, patients with initially poorest metabolic control were not able to improve their physical fitness and did not show significant improvement in metabolic control. In the control group no changes occurred in any parameter of glucose metabolism. The results suggest that physical exercise is beneficial for the glycemic control in patients with mild and moderate non-insulin-dependent diabetes. Increased insulin response is at least one main mechanism of the action of exercise.     

Density and functioning of human lymphocytic beta-adrenergic receptors during prolonged physical exercise

In order to study the regulation of beta-adrenergic receptor number and function in response to prolonged physical effort, lymphocytic beta-adrenoceptor density (determined by (-)[125I]iodocyanopindolol binding), lymphocytic basal and isoproterenol-stimulated cyclic AMP (cAMP) production and concentrations of plasma catecholamines were measured before and during 3 h running exercise in eight healthy volunteers. A significant (P less than 0.01) increase of the lymphocytic beta-adrenoceptor density from 45 +/- 4 to 81 +/- 9 fmol mg-1 protein (mean +/- SEM) took place during the first hour of exercise. As the exercise was continued for up to 2.1-3 h, the receptor densities did not change significantly any more and remained elevated (72 +/- 9 fmol mg-1 protein) in comparison to the resting levels (P less than 0.02). The isoproterenol-stimulated cAMP production of the lymphocytes increased during the first hour of running from 190 +/- 36 to 269 +/- 56 pmol mg-1 protein (P less than 0.01) and returned to the resting level at the end of the exercise (182 +/- 38 pmol mg-1 protein). The mean levels of plasma catecholamines increased approximately sixfold during the first hour of exercise and remained elevated until the end of the running. This study demonstrates that the beta-adrenergic receptor system is activated in lymphocytes during prolonged aerobic physical exercise. This activated state becomes, however, attenuated within 2-3 h of exercise as indicated by a diminishing ability of beta-adrenoceptors to mediate catecholamine-induced cAMP production.     

Activation of sodium transport in human erythrocytes by β-adrenoceptor stimulation in vivo

Summary -adrenoceptor stimulation in vivo shifts potassium into the cells. To examine whether human erythrocytes participate in this process, we measured, along with serum or plasma potassium, the concentrations of potassium and sodium in erythrocytes. -adrenoceptor stimulation was obtained by infusion of either fenoterol or hexoprenaline into 6 volunteers at rest or by endogenous amines provoked in 14 volunteers during ergometric exercise. Metabolic effects were followed at rest on serum insulin, Cpeptide, and growth hormone levels, and during exercise on pH and on lactate concentration in blood. The potassium concentration (mean ±S.E.M.) dropped (p<0.001) in serum from 4.64±0.37 to 3.19±0.43 mmol·l^–1 in the first hour at rest and in plasma from 5.70±0.93 to 4.63±0.45 in 90 sec directly after exercise. The concentration of erythrocyte sodium dropped (p<0.001) from 9.68±0.73 to 8.81±0.62 mmol·l^–1 in cells and from 9.62±1.16 to 8.55±1.24 during exercise for 90 s, respectively. Changes in the concentration ratio of cellular sodium to potassium confirmed this sodium shift.An increased sodium transport in erythrocytes due to -adrenoceptor stimulation in vivo appears to complement a shift of serum potassium into the cells and may be mediated by the membranebound sodium, potassium ATPase.Supported by the Deutsche Forschungsgemeinschaft, grant Bo 425/8-5     

Food intake,body composition and blood lipids following treadmill exercise in male and female rats

Body weight gain, food intake, body composition and blood lipids of male and female Osborne Mendel rats were compared on the same exercise treadmill program. To mimic their nocturnal habits, rats were exercised daily at the beginning of the 12 hour dark cycle and food intake was measured for both light and dark cycles. After a 10 day treadmill adaptation period, the duration of exercise was successively increased over a 12 day period until 60 min/day at 21.3 meters/min was reached. Relative to their respective controls, exercised male rats showed a reduction in body weight and light cycle food intake while female runners showed no change in body weight or food intake. Exercise resulted in a decrease in percent body fat in both males and females while only male runners increased percent protein. Both males and females reduced serum triglycerides while serum cholesterol was reduced only in the males. The short term exercise program produced highly significant changes in the males while the females were more resistant to the same exercise regimen.