Schmid T C, Loffing J, Le Hir M, Kaissling B
Institute of Anatomy, University of Zurich, Switzerland.
Histochemistry. 1994 Jul;101(6):439-47. doi: 10.1007/BF00269494.
In the kidney a striking parallel exists between the expression of ecto-5'-nucleotidase and of erythropoietin by renal fibroblasts. It was therefore hypothesized that the expression of ecto-5'-nucleotidase in fibroblasts might be controlled by oxygen tension. In order to test this hypothesis, we examined the distribution of the enzyme in a tissue which displays a defined zonation in respect to oxygen tension, namely in the liver; anaemia was used in order to exaggerate this zonation. The distribution of ecto-5'-nucleotidase was investigated by light and electron microscopy using enzyme and immunohistochemical methods in the livers of healthy and of anaemic rats. Anaemia was produced by haemolysis combined with X-ray irradiation. The enzyme was detected in the bile canaliculi, in the connective tissue of the portal triads and of the central veins, and in fat-storing cells probably corresponding to a special form of fibroblasts. In healthy animals the perisinusoidal ecto-5'-nucleotidase activity was slightly higher in the pericentral than in the periportal area of the acinus whereas the inverse was observed for the staining of bile canaliculi. Anaemia provoked an increase of ecto-5'-nucleotidase in fat-storing cells in the pericentral zone of the acinus and in fibroblasts around the central veins, resulting in steepended gradients along the sinusoids. The intralobular gradient of ecto-5'-nucleotidase in perisinusoidal cells and the effect thereon of anaemia suggest that the expression of the ecto-5'-nucleotidase might be directly or indirectly controlled by local oxygen tension.
在肾脏中，肾成纤维细胞中外切-5'-核苷酸酶的表达与促红细胞生成素的表达之间存在显著的平行关系。因此，有人推测成纤维细胞中外切-5'-核苷酸酶的表达可能受氧张力控制。为了验证这一假设，我们在一个相对于氧张力呈现明确分区的组织（即肝脏）中研究了该酶的分布；使用贫血来加剧这种分区。采用酶法和免疫组化方法，通过光学显微镜和电子显微镜研究了健康大鼠和贫血大鼠肝脏中外切-5'-核苷酸酶的分布。通过溶血联合X射线照射造成贫血。在胆小管、门三联管和中央静脉的结缔组织以及可能对应于一种特殊形式成纤维细胞的贮脂细胞中检测到了该酶。在健康动物中，腺泡中央周围的窦周外切-5'-核苷酸酶活性略高于门周区域，而胆小管染色情况则相反。贫血导致腺泡中央区贮脂细胞和中央静脉周围成纤维细胞中外切-5'-核苷酸酶增加，沿血窦形成更陡的梯度。窦周细胞中外切-5'-核苷酸酶的小叶内梯度及其对贫血的反应表明，外切-5'-核苷酸酶的表达可能直接或间接受局部氧张力控制。
