高血压大鼠肾脏中的肾单位氧分压和肾脏氧利用情况。
Nephron pO2 and renal oxygen usage in the hypertensive rat kidney.
作者信息
Welch W J, Baumgärtl H, Lübbers D, Wilcox C S
机构信息
Division of Nephrology and Hypertension, Georgetown University Medical Center, Washington D.C. 20007, USA.
出版信息
Kidney Int. 2001 Jan;59(1):230-7. doi: 10.1046/j.1523-1755.2001.00483.x.
BACKGROUND
The kidney has a high rate of oxygen usage (QO2) that is closely dependent on tubular Na+ transport (TNa). However, little is known concerning the regulation of the cortical partial pressure of oxygen (pO2).
METHODS
First, the pO2 was measured in the outer cortical proximal (PT) and distal tubules (DT), efferent arterioles (EA), and superficial (SC) and deep cortical (DC) tissues in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHRs) using an ultramicrocoaxial O2 electrode. We next assessed the determinants of QO2 and tubular reabsorption of sodium (TNa) for whether they could account for any differences in renal cortical pO2 in SHRs.
RESULTS
The pO2 in the EA was reduced 40 to 50% compared with arterial values but was similar in the two strains (WKY rats 45 +/- 2 vs. SHRs 41 +/- 1 mm Hg, P = NS). The pO2 value in the PT, DT, and SC did not differ within strains. All were significantly (P < 0. 001) lower in SHRs (for example, pO2 in PT of WKY rats 39 +/- 1 vs. SHRs, 30 +/- 1 mm Hg). The pO2 in the renal vein was above that at any site in the EA or the cortex, implying a precapillary shunting of O2 from the artery to vein. SHRs had reduced renal blood flow (RBF) leading to a reduced (P < 0.05) rate of O2 delivery (WKY rats 42 +/- 6 vs. SHRs 30 +/- 1 micromol. min-1. g-1) and a reduced glomerular filtration rate, leading to a lower (P < 0.001), TNa (WKYs 115 +/- 9 vs. SHRs 66 +/-8 micromol. min-1. g-1). However, despite the 43% reduction in TNa, the renal O2 usage was not significantly different between strains (WKY rats 7.6 +/- 0.8 vs. SHRs 9.0 +/- 1.0 micromol. min-1. g-1). Therefore, the SHRs had a sharp reduction (P < 0.001) in the O2 efficiency for Na+ reabsorption (TNa/QO2; WKY rats 15.1 +/- 1.6 vs. SHRs 7.3 +/-1.0 micromol-1).
CONCLUSIONS
A precapillary O2 shunt reduces the pO2 of cortical nephrons. The pO2 is reduced further in SHRs because of less efficient O2 usage for Na+ transport.
背景
肾脏的氧耗率（QO2）很高，且与肾小管钠转运（TNa）密切相关。然而，关于皮质氧分压（pO2）的调节知之甚少。
方法
首先，使用超微同轴氧电极测量正常血压的Wistar Kyoto（WKY）大鼠和自发性高血压大鼠（SHR）的外皮质近端（PT）和远端小管（DT）、出球小动脉（EA）以及浅表（SC）和深层皮质（DC）组织中的pO2。接下来，我们评估了QO2和钠的肾小管重吸收（TNa）的决定因素，以确定它们是否可以解释SHR肾皮质pO2的任何差异。
结果
与动脉值相比，EA中的pO2降低了40%至50%，但在两种品系中相似（WKY大鼠为45±2 mmHg，SHR为41±1 mmHg，P = 无显著性差异）。PT、DT和SC中的pO2值在品系内没有差异。所有这些在SHR中均显著降低（P < 0.001）（例如，WKY大鼠PT中的pO2为39±1 mmHg，SHR为30±1 mmHg）。肾静脉中的pO2高于EA或皮质中任何部位的pO2，这意味着氧从动脉到静脉的毛细血管前分流。SHR的肾血流量（RBF）减少，导致氧输送速率降低（P < 0.05）（WKY大鼠为42±6 μmol·min-1·g-1，SHR为30±1 μmol·min-1·g-1），肾小球滤过率降低，导致TNa降低（P < 0.001）（WKY大鼠为115±9 μmol·min-1·g-1，SHR为66±8 μmol·min-1·g-1）。然而，尽管TNa降低了43%，但品系间的肾氧耗量没有显著差异（WKY大鼠为7.6±0.8 μmol·min-1·g-1，SHR为9.0±1.0 μmol·min-1·g-1）。因此，SHR的钠重吸收氧效率急剧降低（P < 0.001）（TNa/QO2；WKY大鼠为15.1±1.6 μmol-1，SHR为7.3±1.0 μmol-1）。
结论
毛细血管前氧分流降低了皮质肾单位的pO2。由于钠转运的氧利用效率较低，SHR中的pO2进一步降低。
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