Younoszai M K, Sapario R S, Laughlin M
J Clin Invest. 1978 Aug;62(2):271-80. doi: 10.1172/JCI109126.
During osmotic diarrhea, loss of water and electrolytes appears to be greater in infants than in adults. In 2-, 3-, and 7-wk-old rats, we studied net transport of H(2)O, Na, and Cl, during in vivo perfusion of segments of the jejunum and ileum, from solutions with osmolalities of 300, 375, 500, or 700 mosmol/kg. In the jejunal segments, from the hypertonic solutions net transport of H(2)O, Na, and Cl was into the lumen and greater in the 2- than 7-wk-old rats. In the ileal segments, transport of water was into the lumen, transport of Na was minimal and variable, whereas transport of Cl was usually out the lumen. In 3-wk-old rats, transport rates were intermediate between those in 2- and 7-wk-old rats. The calculated filtration coefficient (microliters of H(2)O transported per hour per unit osmolality gradient-lumen-serum-per gram dry weight) of water suggested that the resistance to water flow did not increase with rise in luminal hypertonicity in the jejunum of the 2- and 3-wk-old rats, whereas in jejunum of the 7-wk-old rats and in ileum of rats in all three ages, the resistance to water flow increased with the rise in luminal osmolality. The differences in the transport rates and the resistance to water flow, between segments of the 2-, 3-, and 7-wk-old rats, suggested a maturational phenomenon that appears to continue beyond the 3rd wk of life and could have been due to differences in some physical property of the mucosal membrane.
在渗透性腹泻期间，婴儿的水和电解质流失似乎比成人更严重。我们研究了2周龄、3周龄和7周龄大鼠空肠和回肠段在体内灌注渗透压为300、375、500或700毫摩尔/千克溶液时水、钠和氯的净转运情况。在空肠段，从高渗溶液中，水、钠和氯的净转运进入肠腔，2周龄大鼠比7周龄大鼠的转运量更大。在回肠段，水的转运进入肠腔，钠的转运极少且变化不定，而氯的转运通常是从肠腔转出。在3周龄大鼠中，转运速率介于2周龄和7周龄大鼠之间。计算得出的水的滤过系数（每小时每单位渗透压梯度 - 肠腔 - 血清 - 每克干重转运的微升水量）表明，2周龄和3周龄大鼠空肠中对水流的阻力不会随着肠腔高渗性的升高而增加，而在7周龄大鼠的空肠以及所有三个年龄段大鼠的回肠中，对水流的阻力随着肠腔渗透压的升高而增加。2周龄、3周龄和7周龄大鼠各段之间转运速率和对水流阻力的差异表明这是一种成熟现象，这种现象似乎在出生后第3周之后仍在持续，可能是由于黏膜膜某些物理性质的差异所致。
