Effects of ^<13>C-labeled carbohydrate ingestion on the cardiovascular responses to prolonged exercise

^ 13 C标记的碳水化合物摄入对长时间运动的心血管反应的影响

• 批准号: 11680031
• 负责人: SADAMOTO Tomoko
• 金额: $ 2.24万
• 依托单位: Nara Women's University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680031/
• 关键词: stable isotope; glucose; fructose; blood pressure; vasodilatation; central command; metaboreflex; 動脈血圧; ^<13>Cフルクトース; 長時間運動; 呼気ガス分析; 心拍数; 筋血流; ^<13>C; 糖質; 運動; 呼気ガス

Carbohydrate ingestion during prolonged exercise is known to improve endurance performance. It is, however, unclear whether carbohydrate ingestion also affects the cardiovascular adjustments to exercise. To verify this problem, we investigated time courses of oxidation of ingested glucose and fructose and the cardiovascular responses during prolonged exercise. Ten female volunteers exercised on a cycle ergometer at 60 % of maximal workload for first 40 miri (Ex 1) and then 60 min (Ex 2) on three occasions while subjects ingested water only (W) or 5 % of glucose (G) or fructose (F) solution. The subject drank a single bolus of W or G solution (3.4 ml/kg body wt) during 3.5-min resting period spaced between Ex 1 and Ex 2. In G or F solution, ^<13>C-labeled stable isotope glucose or fructose (8.5 mg/kg body wt) was dissolved as a tracer. Oxidation of the ingested glucose or fructose was evaluated by V^<13>CO_2 per V^<12>CO_2 ratio (^<13>C/^<12>-C ratio) in expired gases. Oxygen uptake, me … More an arterial blood pressure (MAP), heart rate (HR), and muscle blood flow (MBF) in thigh muscles measured by near-infrared spectroscopy were continuously recorded. The baseline value was defined as the average during the last 10 min of Ex 1, and the changes from the baseline was calculated for each variable during Ex 2. Rating of perceived exertion (RPE) was also monitored every 5 min during Ex 2. The oxygen uptake during Ex 2 was identical among G, F, and W. The ^<13>C/^<12>C ratio began to increase significantly from 15 mm in G and from!6 min in F and peaked at 37 min inG and at 53 min in F during Ex2. The MAP inG showed a significant decrease before the increase of ^<13>C/^<12>C ratio and sustained at the decreased level till the end of exercise, whereas the MAP in F showed similar levels as seen in W. The attenuated MAP responses in G were accompanied by lower RPE, HR, and MBF. These results indicated that the glucose ingestion had attenuating effects on the MAP adjustment to prolonged exercise whereas the fructose ingestion did not alter the MAP responses. The preceding decrease of MAP observed before the increase of ^<13>C/^<12>C ratio in G was independent of utilization of ingested glucose and probably mediated by insulin-induced vasodilatation in the gastrointestinal tract for digestion. The later sustained decreases in MAP in G were probably mediated by less activation in central command and/or the reduced activation of muscle fibers required to perform the identical exercise. Less

Carbohydrate ingestion during prolonged exercise is known to improve endurance performance.然而，目前尚不清楚碳水化合物的摄入是否也会影响心血管对运动的调节。为了验证这个问题，我们研究了摄入的葡萄糖和果糖氧化的时间过程以及长时间运动期间的心血管反应。十名女性志愿者在自行车测力计上以最大工作量的 60% 进行锻炼，前 40 分钟（Ex 1），然后 60 分钟（Ex 2），共 3 次，受试者只摄入水 (W) 或 5% 的葡萄糖 (G) 或果糖 (F) 溶液。受试者在Ex 1和Ex 2之间间隔的3.5分钟休息期间饮用单次推注的W或G溶液(3.4ml/kg体重)。在G或F溶液中，溶解13C标记的稳定同位素葡萄糖或果糖(8.5mg/kg体重)作为示踪剂。摄入的葡萄糖或果糖的氧化通过呼出气体中的V 13 CO_2 / V 12 CO_2 比率( 13 C/12 -C比率)来评价。通过近红外光谱测量的大腿肌肉的摄氧量、动脉血压（MAP）、心率（HR）和肌肉血流量（MBF）被连续记录。基线值定义为Ex 1最后10分钟期间的平均值，并计算Ex 2期间每个变量相对于基线的变化。在Ex 2期间每5分钟还监测感知用力(RPE)的评级。Ex 2期间G、F和W中的摄氧量是相同的。^ 13 C/^ 12 C比率从G中的15mm和F中的6分钟开始显着增加并达到峰值 Ex2 期间，G 37 分钟和 F 53 分钟。 G中的MAP在^ 13 C/^ 12 C比率增加之前显示出显着降低，并维持在降低的水平直到运动结束，而F中的MAP显示出与W中所见相似的水平。G中的MAP反应减弱伴随着较低的RPE、HR和MBF。这些结果表明，葡萄糖摄入对长时间运动的 MAP 调节具有减弱作用，而果糖摄入不会改变 MAP 反应。在G中的^ 13 C/^ 12 C比率增加之前观察到的MAP的先前降低与摄入的葡萄糖的利用无关并且可能由胃肠道中用于消化的胰岛素诱导的血管舒张介导。后来 G 中 MAP 的持续降低可能是由于中枢命令激活减少和/或执行相同运动所需的肌纤维激活减少介导的。较少的