Planas J M, Ferrer R, Moretó M
Pflugers Arch. 1987 May;408(5):515-8. doi: 10.1007/BF00585078.
We have investigated the possible relation between the phloridzin-sensitive influx of alpha-methyl-D-glucoside (concentration 5 mmol/l) and the brush border surface area, in chicken isolated enterocytes. The intestinal regions studied were: jejunum and proximal cecum (both with high affinity sugar transport sites), medial cecum (with a low affinity transport system) and distal cecum (which lacks any transport ability). Cell apical surface measured by electron microscopy gave the following results; jejunal cells (0.41 micron 2) greater than proximal cecal cells (0.23 micron 2) greater than medial cecal cells (0.15 micron 2) = distal cecal cells (0.14 micron 2). This parameter is mainly determined by the length of microvilli. Sugar influx studies showed that the concentration of the substrate in cell water (in mmol/l) was jejunum (7.1) greater than proximal cecum (2.9) greater than medial cecum (1.7) greater than distal cecum (not different from zero). The decline in influx rate from proximal to distal cecum may be explained both by changes in surface and by the different carriers involved (different Km). Results of sugar concentration in the distal cecal cells do not correlate with the other segments studied since the substrate enters in these cells by a passive process. It is concluded that the degree of development of microvilli should be taken into account when estimating nutrient transport rates in different intestinal segments.
我们研究了在鸡的离体肠上皮细胞中，根皮苷敏感的α-甲基-D-葡萄糖苷（浓度5 mmol/L）内流与刷状缘表面积之间的可能关系。所研究的肠道区域为：空肠和近端盲肠（均具有高亲和力糖转运位点）、中间盲肠（具有低亲和力转运系统）和远端盲肠（缺乏任何转运能力）。通过电子显微镜测量的细胞顶端表面积得出以下结果：空肠细胞（0.41平方微米）大于近端盲肠细胞（0.23平方微米）大于中间盲肠细胞（0.15平方微米）=远端盲肠细胞（0.14平方微米）。该参数主要由微绒毛的长度决定。糖内流研究表明，细胞内水中底物的浓度（以mmol/L计）为空肠（7.1）大于近端盲肠（2.9）大于中间盲肠（1.7）大于远端盲肠（与零无差异）。从近端盲肠到远端盲肠内流速率的下降可能是由表面积的变化以及所涉及的不同载体（不同的Km）共同解释的。远端盲肠细胞中糖浓度的结果与所研究的其他节段不相关，因为底物是以被动过程进入这些细胞的。得出的结论是，在估计不同肠段的营养物质转运速率时，应考虑微绒毛的发育程度。
