Macagno E O, Christensen J, Lee C L
Am J Physiol. 1982 Dec;243(6):G541-50. doi: 10.1152/ajpgi.1982.243.6.G541.
Intestinal wall movements may influence intestinal absorption by inducing flow in the luminal volume. Direct evidence for this is scant and weak. Such evidence was sought by mechanical and analytical modeling. Wall motions resembling peristaltic ring contractions were induced in dialysis tubing filled with a concentrated salt solution and immersed in tap water. The disappearance of solute from the inside of the tube was monitored with conductivity probes and correlated with various kinds of wall motions. In analytical modeling, equations representing wall motions, flow, and mass transfer were constructed, with the assumptions that ring contractions are axisymmetric, the wall is totally compliant, the Reynolds' number is low, the fluid volume is conserved, the no-slip condition exists at the luminal surface, and inertial flow is negligible. In the mechanical model, wall motions caused a 30-35% increase in absorption that was matched in the corresponding analytical model. The analytical model demonstrated that the effect is progressively greater for nonpropagative stationary contractions, asymmetric progressive contractions, and symmetric progressive contractions, the increase being 33, 70, and 100%, respectively.
肠壁运动可能通过促使管腔内液体流动来影响肠道吸收。对此的直接证据稀少且不充分。通过机械建模和分析建模来寻找此类证据。在装满浓盐溶液并浸于自来水中的透析管内引发类似蠕动环收缩的壁运动。用导电探针监测管内溶质的消失情况，并将其与各种壁运动相关联。在分析建模中，构建了代表壁运动、流动和传质的方程，假设环收缩是轴对称的，壁完全柔顺，雷诺数低，流体体积守恒，管腔表面存在无滑移条件，且惯性流动可忽略不计。在机械模型中，壁运动使吸收增加了30%至35%，这在相应的分析模型中得到了匹配。分析模型表明，对于非传播性静止收缩、不对称渐进收缩和对称渐进收缩，这种效应逐渐增大，增加幅度分别为33%、70%和100%。
