Schurek H J, Jost U, Baumgärtl H, Bertram H, Heckmann U
Department of Internal Medicine, Medizinische Hochschule Hannover, Federal Republic of Germany.
Am J Physiol. 1990 Dec;259(6 Pt 2):F910-5. doi: 10.1152/ajprenal.1990.259.6.F910.
Although blood flow to the renal cortex is high and oxygen extraction is low, the renal cortex is remarkably susceptible to hypoxia. Because erythropoietin production has been localized mainly to the renal cortex, the aim of this study was to find a common denominator for both the high susceptibility to hypoxia and oxygen sensing within the renal cortex. By direct measurement of oxygen pressure with microcoaxial needle sensors at superficial glomeruli of the in situ kidney of anesthetized Munich-Wistar-Frömter rats, we obtained mean partial pressure of O2 (PO2) values of 46 +/- 13 (SD) mmHg (n = 71). The simultaneously measured systemic PO2 in arterial blood was 90 +/- 8 mmHg (n = 54). Changing the respirator gas from air to pure oxygen enhanced systemic arterial PO2 to 593 +/- 27 mmHg, whereas PO2 at the superficial glomeruli increased only to a mean of 80 +/- 28 mmHg (n = 71). These data suggest significant preglomerular shunting of oxygen within the cortical vasculature, most likely between interlobular vessels, which are arranged in a countercurrent fashion and represent quantitatively the largest contact area between arteries and veins within the renal cortex.
尽管肾皮质的血流量高且氧摄取率低，但肾皮质对缺氧却非常敏感。由于促红细胞生成素的产生主要定位于肾皮质，本研究的目的是找到肾皮质对缺氧高度敏感和氧感知的共同因素。通过用微同轴针传感器直接测量麻醉的慕尼黑 - 威斯塔 - 弗勒姆特大鼠原位肾脏浅表肾小球处的氧分压，我们获得的氧分压（PO2）平均值为46±13（标准差）mmHg（n = 71）。同时测量的动脉血中全身PO2为90±8 mmHg（n = 54）。将呼吸气体从空气改为纯氧可使全身动脉PO2升高至593±27 mmHg，而浅表肾小球处的PO2仅平均升高至80±28 mmHg（n = 71）。这些数据表明皮质血管系统内存在明显的肾小球前氧分流，最有可能发生在小叶间血管之间，小叶间血管以逆流方式排列，在数量上代表了肾皮质内动脉和静脉之间最大的接触面积。
