Pagel H, Jelkmann W, Weiss C
Institut für Physiologie, Medizinische Universität zu Lübeck, Federal Republic of Germany.
Pflugers Arch. 1988 Nov;413(1):62-6. doi: 10.1007/BF00581229.
It is generally assumed that the O2 supply to the kidneys is the major determinant of the synthesis of erythropoietin (Ep). In the present study, the O2 supply of the kidneys of rats was lowered by the reduction of renal blood flow (rbf). Plasma Ep was determined after about 18 h of bilateral application of Goldblatt clips with graded inner diameters. The results were compared to findings in anemic rats, in which the systemic O2 supply was lowered by exchange transfusion of blood with plasma. We found a linear correlation between Ep levels in plasma and the degree of reduction of rbf. However, there was an exponential relationship between Ep levels and the concentration of hemoglobin in blood. In addition, the elevation of plasma Ep was only moderate, when rbf was reduced (maximum 0.07 IU Ep/ml plasma). The increase in Ep concentration was much more pronounced in anemia (up to about 7 IU Ep/ml plasma). From these results it may be concluded that decreasing oxygen supply to the kidney through reduction in renal blood flow (ischemic hypoxia) is less effective in increasing erythropoietin production than reducing the hemoglobin concentration (anemic hypoxia). The possibility must be considered that the increase in renal production of erythropoietin due to anemic hypoxia is triggered by one or more extrarenal signals.
一般认为，肾脏的氧气供应是促红细胞生成素（Ep）合成的主要决定因素。在本研究中，通过减少肾血流量（rbf）来降低大鼠肾脏的氧气供应。在双侧应用不同内径的戈德布拉特夹约18小时后测定血浆Ep。将结果与贫血大鼠的结果进行比较，贫血大鼠通过用血浆进行换血来降低全身氧气供应。我们发现血浆中Ep水平与rbf降低程度之间存在线性关系。然而，Ep水平与血液中血红蛋白浓度之间存在指数关系。此外，当rbf降低时，血浆Ep的升高仅为中等程度（最高0.07 IU Ep/ml血浆）。在贫血时Ep浓度的增加更为明显（高达约7 IU Ep/ml血浆）。从这些结果可以得出结论，通过减少肾血流量（缺血性缺氧）来降低肾脏的氧气供应，在增加促红细胞生成素产生方面比降低血红蛋白浓度（贫血性缺氧）效果更差。必须考虑到这样一种可能性，即贫血性缺氧导致的肾脏促红细胞生成素产生增加是由一个或多个肾外信号触发的。
