^125I在鹌鹑Coturnix coturnix中的吸收动态及其分布

利用同位素示踪法研究了125I(NaI)在鹌鹑Coturnix coturnix中的吸收动态及其分布.鹌鹑对经口喂的125I的吸收过程可以分为快清除期和平台期,0～1 d为快清除期,在这期间,鹌鹑快速的排出进入体内的125I.1～7 d为平台期,鹌鹑体内的125I维持在一个相对恒定的平台,此时体内的放射性活度占起始活度的10%～15%,表明鹌鹑能利用部分进入体内的碘.进入体内的125I主要分布于甲状腺中,5 h时125I在甲状腺中的比活度高达6180 060Bq·g-1,约占体内总量的75%～80%.     

Effects of zinc on cadmium uptake by spring wheat （Triticum aestivum, L.）： long-time hydroponic study and short-time ^109Cd tracing study

To investigate effects of Zn on Cd uptake by spring wheat (Triticum aestivum, L.) in solution culture, long-time hydroponic experiment (1 month) (Experiment 1) and short-time Cd isotope (109Cd) tracing experiment (24 h) (Experiment 2) were conducted. In Experiment 1, spring wheat (cv. Brookton) was grown in nutrient solution at uniform cadmium concentration of 20μ mol/L and 10 zinc concentrations (0, 1, 5, 10, 20, 100, 200, 500, 1000, 2000 μ mol/L). In Experiment 2, spring wheat seedlings,pre-cultivated in complete nutrient solution, were treated with 109Cd of uniform activity and the same series of Zn concentrations as those in Experiment 1 for 24 h. Cd concentrations in shoots and roots in Experiment 1 increased marginally but not consistently with Zn increasing at Zn rates of 1～200 μmol/L, and then decreased significantly at high rates (＞200 μ mol/L). In Experiment 2, the response of 109Cd activities in shoots and roots to increasing Zn was greatly similar to the response of Cd concentrations to Zn increasing in Experiment 1. The results of the two experiments indicated that the short-time and long-time exposure of spring wheat to Zn had similar effects on Cd accumulation.     

论骨骼肌内葡萄糖的转运

骨骼肌是葡萄糖最主要的利用者,同时也是碳水化合物的主要贮藏部位（占糖原总量的70％）。本文介绍了在运动过程中骨骼肌对葡萄糖利用及骨骼肌对葡萄糖利用的潜在机理。     

登楼梯能量消耗的测量与统计方法研究

目的:了解登楼梯能量消耗状况以及探讨能耗测量和计算方法.方法:30名受试者登12层楼(每级台阶高度16 cm,共204级台阶,垂直距离32.6 m),每位受试者以90步/min和100步/min的步频上下两次楼梯.在登楼梯过程中,通过便携式肺功能仪(德国CORTEX MgtaMax 3B)测量受试者的摄氧量、通气量、能耗、心率、呼吸商、氧脉搏等指标.结果:上下楼梯的能量消耗比是2.7;1;在一定步频范围内,随着步频的提高,能耗相应增加,两者呈线性关系.以90～100步/min上下楼梯可以代表日常登楼速度;以90～100步/min登12层楼的运动时间不到3 min,多数受试者的能耗、心率等生理指标经过快速上升期后进入稳定状态;登楼梯的能耗值有明显的年龄和性别差异,20岁组男性显著高于50岁组男性和20岁组女性;利用多项式回归建立的登楼梯能耗预测方程,能够准确反映日常爬不同楼层的能量消耗值.     

Peak aerobic power and paddling efficiency in recreational and competitive junior male surfers

Abstract

The purpose of the present study was to measure and compare peak oxygen uptake and paddling efficiency in recreational and competitive junior male surfers. Eight male recreational surfers (mean age 18 years, s=2; mass 66.8 kg, s=13.0; height 1.75 m, s=0.10) and eight male competitive surfers (mean age 18 years, s=1; mass 68.0 kg, s=11.7; height 1.72 m, s=0.10) performed an incremental paddling test consisting of four 3-min constant load work stages followed by a ramp increase in power output of 20 W · 30 s^?1 until exhaustion. The oxygen uptake–power output relationship of the four constant load work stages and peak values obtained during the incremental paddling test were used to calculate paddling efficiency. No differences (P>0.05) were observed between the recreational and competitive surfers for peak oxygen uptake (recreational: 2.52 litres · min^?1, s=0.5; competitive: 2.66 litres · min^?1, s=0.35) or efficiency (recreational: 24%, s=3; competitive: 21%, s=4). Blood lactate concentration was significantly greater in recreational (2.4 mmol · l^?1, s=0.9) than competitive surfers (1.6 mmol · l^?1, s=0.5) during submaximal paddling. There were no differences in peak oxygen uptake or paddling efficiency between recreational and competitive surfers suggesting that peak oxygen uptake and efficiency are not sensitive to differences in surfing ability. The increase in blood lactate concentration during submaximal paddling in recreational compared with competitive surfers suggests that other determinants of paddling endurance, such as blood lactate threshold, might be better at distinguishing surfers of differing ability.     

The influence of a 6.5% carbohydrate-electrolyte solution on performance of prolonged intermittent high-intensity running at 30°C

Nine male student games players consumed either flavoured water (0.1 g carbohydrate, Na⁺ 6 mmol · l^?1), a solution containing 6.5% carbohydrate-electrolytes (6.5 g carbohydrate, Na⁺ 21 mmol · l^?1) or a taste placebo (Na⁺ 2 mmol · l^?1) during an intermittent shuttle test performed on three separate occasions at an ambient temperature of 30°C (dry bulb). The test involved five 15-min sets of repeated cycles of walking and variable speed running, each separated by a 4-min rest (part A of the test), followed by 60 s run/60 s rest until exhaustion (part B of the test). The participants drank 6.5 ml · kg^?1 of fluid as a bolus just before exercise and thereafter 4.5 ml · kg^?1 during every exercise set and rest period (19 min). There was a trial order effect. The total distance completed by the participants was greater in trial 3 (8441 ± 873 m) than in trial 1 (6839 ± 512, P < 0.05). This represented a 19% improvement in exercise capacity. However, the trials were performed in a random counterbalanced order and the participants completed 8634 ± 653 m, 7786 ± 741 m and 7099 ± 647 m in the flavoured water (FW), placebo (P) and carbohydrate-electrolyte (CE) trials, respectively (P = 0.08). Sprint performance was not different between the trials but was impaired over time (FW vs P vs CE: set 1, 2.41 ± 0.02 vs 2.39 ± 0.03 vs 2.39 ± 0.03 s; end set, 2.46 ± 0.03 vs 2.47 ± 0.03 vs 2.47 ± 0.02 s; main

effect time, P < 0.01). The rate of rise in rectal temperature was greater in the carbohydrate-electrolyte trial (rise in rectal temperature/duration of trial, °C · h^?1; FW vs CE, P < 0.05; P vs CE, N.S.). Blood glucose concentrations were higher in the carbohydrate-electrolyte than in the other two trials (FW vs P vs CE: rest, 4.4 ± 0.1 vs 4.3 ± 0.1 vs 4.2 ± 0.1 mmol · l^?1; end of exercise, 5.4 ± 0.3 vs 6.4 ± 0.6 vs 7.2 ± 0.5 mmol · l^?1; main effect trial, P < 0.05; main effect time, P < 0.01). Plasma free fatty acid concentrations at the end of exercise were lower in the carbohydrate-electrolyte trial than in the other two trials (FW vs P vs CE: 0.57 ± 0.08 vs 0.53 ± 0.11 vs 0.29 ± 0.04 mmol · l^?1; interaction, P < 0.01). The correlation between the rate of rise in rectal temperature (°C · h^?1) and the distance completed was ?0.91, ?0.92 and ?0.96 in the flavoured water, placebo and carbohydrate-electrolyte conditions, respectively (P < 0.01). Heart rate, blood pressure, plasma ammonia, blood lactate, plasma volume and rate of perceived exertion were not different between the three fluid trials. Although drinking the carbohydrate-electrolyte solution induced greater metabolic changes than the flavoured water and placebo solutions, it is unlikely that in these unacclimated males carbohydrate availability was a limiting factor in the performance of intermittent running in hot environmental conditions.     

肌酸补充和电刺激对C2C12肌管糖摄入的效应及机制研究

目的:旨在研究肌酸补充(CS)和电刺激(ES)对C2C12肌管葡萄糖摄取相关通路蛋白含量和基因表达的影响,阐明肌酸对GLUT4调节的相关信号通路,并讨论CS是否对ES具有叠加效应,为肌酸提高耐力水平提供新的理论依据。研究方法:0.5mM和2 mM浓度的肌酸孵育分化5 d的肌管48h,然后电刺激(15V,30ms,3Hz)共分化7d的肌管120 min。结果:ES引起AMPK-α2和GLUT4 mRNA表达及GLUT4蛋白含量显著增加(P<0.05),糖原显著下降(P<0.05)。不同浓度的CS没有引起AMPK-α2 mRNA表达变化,却使得GLUT4 mRNA和蛋白含量显著增加(P<0.05),糖原含量也无显著性增加(P>0.05)。ES+CS组与C组和同浓度CS组相比,明显上调AMPK-α2 mRNA和GLUT4 mRNA表达及GLUT4蛋白含量(P<0.05)。结论:1)15V,30ms,3Hz的刺激参数,ES120min没有引起细胞膜明显损伤,是研究耐力运动对肌肉糖代谢影响的适合参数。2)ES能通过AMPK途径增加肌管糖摄入和糖转运。3)单纯CS对肌管糖含量没影响,肌酸或许是通过AMPK非依赖性通路调节糖摄入。4)CS对ES对糖摄入的调节具有叠加效应。     

瑞士球核心稳定性训练对心肺及其调节功能影响的实验研究

观察为期四周瑞士球核心稳定性训练（球上跪姿抬臂）对普通女大学生心率变异性和最大吸氧量的影响规律。利用芬兰产的POLAR S810i遥测心率表及瑞典产的MONARK 839E有氧功率车为工具,测量比较了四周瑞士球核心稳定性训练前后18名普通女大学生（实验组10人,对照组8人）心率变异性指标、最大吸氧量以及血压、心率的变化。经过四周锻炼,实验组的10名受试者均能在瑞士球上维持跪姿抬臂标准姿势5min。实验组最大吸氧量绝对值呈现极显著性增加（P〈0.01）,相对值呈现显著性增加（P〈0.05）、舒张压、心率则出现了显著性降低（P〈0.05）;SD、RMSSD以及HF都出现了显著性增加（P〈0.05）。对照组各项指标均未出现显著性差异（P〉0.05）。四周瑞士球核心稳定性训练可显著提高心肺功能,降低安静时交感神经的紧张性,增加副交感神经的紧张性。提示该训练方法对强身健体、缓解压力可能有显著性作用。     

Recovery of pulmonary diffusing capacity after maximal exercise

Abstract

Pulmonary diffusing capacity (Dl_co), together with spirometric variables, arterial oxygen tension (paO₂) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and erogmeter rowing. Independent of the type of exercise, Dl_co increased immediately post‐exercise from a median 13.6 (range 7.3–16.3) to 15.1 (9.3–19.6) mmol min^‐1 kPa^‐1 (P <0.01). However, it decreased to 11.6 (6.9–15.5) mmol min^‐1 kPa^‐1 (P <0.01) after 24 h with cardiac output and paO₂ at resting values, and Dl_co normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post‐exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in Dl_co. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0–47.0) to 47.1 (42.7–49.8) (P <0.01), had normalized at the time of the decrease in Dl_co. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid‐expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0–7.6) to 7.0 (5.1–7.8) litres (P <0.05) immediately after exercise and remained elevated at 6.9 (5.1–8.7) litres (P <0.05) when a decrease in Dl_co was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in Dl_co takes place 2–3 h post‐exercise, which normalizes during the following day of recovery.     

Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes

Abstract

Three textiles with increasing compressive surface were compared with non-compressive conventional clothing on physiological and perceptual variables during sub-maximal and maximal running. Fifteen well-trained endurance athletes (mean ± s: age 27.1 ± 4.8 years, [Vdot]O_2max 63.7 ± 4.9 ml · min^?1 · kg^?1) performed four sub-maximal (～70%[Vdot]O_2max) and maximal tests with and without different compression stockings, tights, and whole-body compression suits. Arterial lactate concentration, oxygen saturation and partial pressure, pH, oxygen uptake, and ratings of muscle soreness were recorded before, during, and after all tests. In addition, we assessed time to exhaustion. Sub-maximal (P = 0.22) and maximal oxygen uptake (P = 0.26), arterial lactate concentration (P = 0.16; 0.20), pH (P = 0.23; 0.46), oxygen saturation (P = 0.13; 0.26), and oxygen partial pressure (P = 0.09; 0.20) did not differ between the types of clothing (effect sizes = 0.00–0.45). Ratings of perceived exertion (P = 0.10; 0.15), muscle soreness (P = 0.09; 0.10) and time to exhaustion (P = 0.16) were also unaffected by the different clothing (effect sizes = 0.28–0.85). This was the first study to evaluate the effect on endurance performance of different types of compression clothing with increasing amounts of compressive surface. Overall, there were no performance benefits when using the compression garments.