Parmentier M
Laboratoire d'Histologie and IRIBHN, Université Libre de Bruxelles, Belgium.
Biol Cell. 1990;68(1):43-9. doi: 10.1111/j.1768-322x.1990.tb00892.x.
The distribution of calbindin D28k in the digestive system and the urinary bladder of the toad was investigated using immunohistochemistry and Western blotting. By analogy with mammals and birds, the protein was expected to be located preferentially in the duodenal part of the intestine. Interestingly, absorptive cells of the duodenum were totally devoid of calbindin D28k while the colon contained high amounts of the calcium-binding protein. This reversed polarity of calbindin D28k content in the toad intestine should obviously correspond to a different scheme of calcium absorption regulation between amphibians and higher vertebrates. Calbindin D28k containing neuroendocrine-like cells were found scattered in the proximal parts of the gut with a similar distribution to what has been described in rat and chick intestine. The oesophagus, the stomach, and the intrinsic nervous system of the intestine were negative. No significant amounts of the proteins were found in the urinary bladder, which is known to be a site of Ca2+ active transport.
采用免疫组织化学和蛋白质印迹法，研究了蟾蜍消化系统和膀胱中钙结合蛋白D28k的分布情况。类比哺乳动物和鸟类，预期该蛋白优先定位在肠道的十二指肠部分。有趣的是，十二指肠的吸收细胞完全没有钙结合蛋白D28k，而结肠含有大量的钙结合蛋白。蟾蜍肠道中钙结合蛋白D28k含量的这种相反极性显然与两栖动物和高等脊椎动物之间不同的钙吸收调节模式相对应。发现含钙结合蛋白D28k的神经内分泌样细胞散在于肠道近端，其分布与大鼠和鸡肠道中所描述的相似。食管、胃和肠道的内在神经系统均为阴性。在已知是Ca2+主动转运部位的膀胱中未发现大量该蛋白。
