Does oral ingestion of nutrients during exercise interfere with the blood flow to exercising skeletal muscles?

营养摄入引起内脏血流量的显著增加，因为胃肠道器官需要能量供应来消化和吸收摄入的营养物质。相反，运动刺激会导致内脏血流量的减少，从而使更多的心输出量流向运动的骨骼肌。当这些相反的信号同时出现时，我们还不知道营养和运动之间哪个信号更重要，也不清楚心血管系统是如何在运动中妥协这些相互冲突的需求的。本研究的目的就是要探讨这些问题。在第一个实验中，我们确定了在休息和持续静态运动期间，口服葡萄糖和果糖是否会增加肠系膜上动脉（供应胃肠道的大动脉之一）的血流量。10名健康女性志愿者口服100-140毫升5%的葡萄糖或果糖，休息时污染更严重。采用多普勒超声技术测定SMA （SMBF）血流量，心电法和Finapres法测定心率和动脉血压。结果发现，葡萄糖摄入后约15mm的SMBF显著增加，而果糖摄入对SMBF没有影响，尽管两种饮料的体积和浓度相同。在第二个实验中，这些受试者也加入了实验，在摄入5%葡萄糖溶液之前和之后，以最大自愿收缩量的30%进行持续的静态握力运动2 mm。结果表明，运动并没有改变静息水平的SMBF，而是在持续运动结束时略有增加。摄取葡萄糖后运动时SMBF的轻微增加明显大于摄取葡萄糖前运动时。这些结果表明，饮用葡萄糖溶液的刺激可能比运动刺激更强。在某种程度上，SMA可能不受运动过程中血流减少的影响。在第三个实验中：第一个实验的结果提出了一个问题，SMA是否不是由骨骼运动引起的肌肉代谢反射的靶血管，尽管肌肉代谢反射被认为会导致内脏血管床的减少。为了验证这个问题，我们检查了运动后肌肉缺血对SMBF的影响。受试者进行与第一次实验相同的静态运动，随后进行3分钟动脉闭塞。动脉闭塞是通过在运动前臂上臂施加22omhg以上的压力袖带膨胀来完成的。运动后缺血显示，在摄入葡萄糖之前和之后的运动中，SMBF显著增加。运动后肌肉缺血期间观察到的SMBF的增加与动脉血压的显著增加是平行的。从这些结果来看，SMA对肌肉代谢反射不敏感，运动后缺血时SMBF的显著增加与动脉血压升高有关。少

Nutrient ingestion induces a profound increase in the splanchnic blood flow because the gastrointestinal organs lemand energy supply for digesting and absorbing the nutrients ingested. On the contrary, exercise stimulus causes a decrease in the splanchnic blood flow to drive a lager portion of cardiac output to the exercising skeletal muscles. It has not yet been known which signal between nutrition and exercise has a priority when these opposite signals occurred simultaneously It is also unclear how the cardiovascular system compromises these conflicting demands during exercise. The pin-pose in the present study is to investigate these questions. In the first experiments : We determined whether oral ingestion of glucose and fructose increased the blood flow in superior mesenteric artery (SMA), one of major arteries supplied to the gastrointestinal tract, during rest and sustained static exercise. Ten healthy female volunteers orally ingested 100-140 ml of 5 % of glucose or fructose so … More lution during rest. The blood flow in SMA (SMBF) was measured by Doppler ultrasound technique, and heart rate and arterial blood pressure measured by ECG and Finapres methods. It was found that the glucose ingestion produced a significant increase in SMBF approximately 15 mm after the ingestion, whereas the fructose ingestion had no effects on SMBF despite the identical volume and concentration in both drinks. In the second experiments : These subjects also joined the experiments to perform sustained static handgrip exercise at 30 % of maximum voluntary contraction for 2 mm before and after ingestion of 5 % glucose solution. The results showed that the exercise did not change SMBF from the resting level and rather increased slightly at the end of sustained exercise. The slight increase in SMBF was significantly greater during exercise after glucose ingestion than that during the exercise before glucose ingestion. These results indicated that drinking glucose solution was probably more powerful stimulus than the exercise stimulus. The SMA might be to some degree exempt from flow-reducing participation during exercise. In the third experiments : The results in the first experiments raise a question whether SMA was not a target vessel for the muscle metaboreflex arising from exercising skeletal although the muscle metaboreflex has been believed to induce a reduction in the splanchnic vascular beds. To verify this question, we examined the effects of postexercise muscle ischemia on SMBF. The subjects performed the same static exercise as mentioned in the first experiments and followed by a 3-min arterial occlusion. The arterial occlusion was done by pressure cuff inflation above 22OmmHg applied to the upper arm of exercised forearm. The postexercise ischemia showed a significant increase in SMBF in both exercise performed before and after glucose ingestion. The increase in SMBF observed during postexercise muscle ischemia was in parallel with the significant increase in arterial blood pressure. From these results, it appeared that SMA was not sensitive to the muscle metaboreflexes and that the profound increase in SMBF during postexercise ischemia was related to the elevation of arterial blood pressure. Less