Lambert G P, Chang R T, Xia T, Summers R W, Gisolfi C V
Department of Exercise Science, University of Iowa, Iowa City, Iowa 52242-1111, USA.
J Appl Physiol (1985). 1997 Jul;83(1):204-12. doi: 10.1152/jappl.1997.83.1.204.
This study evaluated intestinal absorption from the first 75 cm of the proximal small intestine during 85 min of cycle exercise [63.6 +/- 0.7% peak O2 consumption (VO2 peak)] while subjects ingested either an isotonic carbohydrate-electrolyte beverage (CHO-E) or a water placebo (WP). The CHO-E beverage contained 117 mM (4%) sucrose, 111 mM (2%) glucose, 18 meq Na+, and 3 meq K+. The two experiments were performed a week apart by seven subjects (6 men and 1 woman; mean VO2 peak = 53.5 +/- 6.5 ml . kg-1 . min-1). Nasogastric and multilumen tubes were fluoroscopically positioned in the gastric antrum and duodenojejunum, respectively. Subjects ingested 23 ml/kg body weight of the test solution, 20% (383 +/- 11 ml) of this volume 5 min before exercise and 10% (191 +/- 5 ml) every 10 min thereafter. By using the rate of gastric emptying (18.1 +/- 1.1 vs. 19.2 +/- 0. 7 ml/min for WP and CHO-E, respectively) as the rate of intestinal perfusion, intestinal absorption was determined by segmental perfusion from the duodenum (0-25 cm) and jejunum (25-50 and 50-75 cm). Water flux was different (P < 0.05) between solutions in the 0- to 25- and 25- to 50-cm segments for WP vs. CHO-E (30.7 +/- 2.7 vs. 15.0 +/- 2.9 and 3.8 +/- 1.1 vs. 11.9 +/- 3.3 ml . cm-1 . h-1, respectively). Furthermore, water flux differed (P < 0.05) for WP in a comparison of the 0- to 25- to the 25- to 50-cm segment. Total solute flux (TSF) was not significantly different among segments for a given solution or between solutions for a given segment. There was no difference between trials for percent change in plasma volume. These results indicate that 1) fluid absorption in the proximal small intestine depends on the segment studied and 2) solution composition can significantly effect water absorption rate in different intestinal segments.
本研究评估了在85分钟的周期性运动[达到峰值耗氧量（VO₂峰值）的63.6±0.7%]过程中，近端小肠前75厘米的肠道吸收情况，期间受试者摄入等渗碳水化合物 - 电解质饮料（CHO - E）或水安慰剂（WP）。CHO - E饮料含有117 mM（4%）蔗糖、111 mM（2%）葡萄糖、18 meq钠和3 meq钾。七名受试者（6名男性和1名女性；平均VO₂峰值 = 53.5±6.5 ml·kg⁻¹·min⁻¹），相隔一周进行了这两项实验。通过荧光镜检查将鼻胃管和多腔管分别置于胃窦和十二指肠空肠处。受试者摄入23 ml/kg体重的测试溶液，运动前5分钟摄入该体积的20%（383±11 ml），此后每10分钟摄入10%（191±5 ml）。以胃排空速率（WP和CHO - E分别为18.1±1.1和19.2±0.7 ml/min）作为肠道灌注速率，通过从十二指肠（0 - 25厘米）和空肠（25 - 50厘米和50 - 75厘米）进行分段灌注来测定肠道吸收。对于WP和CHO - E，0至25厘米段和25至50厘米段溶液中的水通量不同（P < 0.05）（分别为30.7±2.7和15.0±2.9以及3.8±1.1和11.9±3.3 ml·cm⁻¹·h⁻¹）。此外，比较WP的0至25厘米段和25至50厘米段时，水通量也不同（P < 0.05）。对于给定溶液，各段之间或对于给定段，不同溶液之间的总溶质通量（TSF）无显著差异。两次试验之间血浆量的百分比变化没有差异。这些结果表明：1）近端小肠中的液体吸收取决于所研究的肠段；2）溶液成分可显著影响不同肠段的水吸收速率。
