Christiansen Rolf E F, Roald Anca B, Tenstad Olav, Iversen Bjarne M
Renal Research Group, Institute of Medicine, University of Bergen, Norway.
Kidney Blood Press Res. 2002;25(5):322-8. doi: 10.1159/000066792.
BACKGROUND/AIMS: Cross-transplantation studies between animals with genetic hypertension and normotensive animals indicate a key role of the kidney in development of hypertension, and studies in young spontaneously hypertensive rats (SHR) have shown reduced glomerular filtration rate (GFR) and renal blood flow (RBF) for a short period at the age of 4-6 weeks during blood pressure increase. We tested the hypothesis that a decline in GFR during development of hypertension in SHR might be more pronounced in juxtamedullary cortex than other cortical zones.
By use of the aprotinin method, total and zonal cortical GFR was measured in anaesthetized Wistar-Kyoto (WKY) rats and SHR at the ages of 2, 4, 6, 8 and 10 weeks. RBF was measured by a transit time flowmeter.
Body and kidney weights in SHR and WKY were not significantly different in any age group (p >0.05). Mean arterial blood pressure (MAP) was not different at the age of 2 weeks (79 +/- 6 mm Hg in SHR and 74 +/- 5 mm Hg in WKY, p > 0.05), but was significantly higher in 4-week-old SHR (104 +/- 1 mm Hg) compared to 4-week-old WKY (77 +/- 3 mm Hg) (p < 0.01). The difference in blood pressure increased with age from 4 to 10 weeks. RBF, total GFR, and outer, middle, and inner cortical GFR increased with age but were not different in SHR and WKY in any age group (p >0.05). Renal vascular resistance was increased from 4 weeks of age in SHR (21.5 +/- 1.8), significantly higher than WKY (14.4 +/- 0.9 mm Hg x ml(-1) x min.g) (p < 0.01) and stayed at higher values in older age groups (p < or = 0.01).
RBF, total and zonal GFR are not significantly different in anaesthetized SHR compared to WKY at ages from 2 to 10 weeks and GFR in juxtamedullary cortex is not decreased in SHR during onset of hypertension. The results from the present study indicate that development of hypertension cannot be explained by a temporary decline in RBF or total or zonal GFR.
背景/目的：遗传性高血压动物与血压正常动物之间的交叉移植研究表明，肾脏在高血压发展过程中起关键作用。对幼年自发性高血压大鼠（SHR）的研究显示，在4至6周龄血压升高期间，肾小球滤过率（GFR）和肾血流量（RBF）会在短时间内降低。我们检验了以下假设：在SHR高血压发展过程中，近髓质皮质的GFR下降可能比其他皮质区域更明显。
使用抑肽酶法，在2、4、6、8和10周龄的麻醉Wistar - Kyoto（WKY）大鼠和SHR中测量总皮质GFR和分区皮质GFR。用通过时间流量计测量RBF。
在任何年龄组中，SHR和WKY的体重和肾脏重量均无显著差异（p>0.05）。2周龄时平均动脉血压（MAP）无差异（SHR为79±6 mmHg，WKY为74±5 mmHg，p>0.05），但4周龄SHR（104±1 mmHg）显著高于4周龄WKY（77±3 mmHg）（p<0.01）。4至10周龄时，血压差异随年龄增加。RBF、总GFR以及皮质外层、中层和内层GFR随年龄增加，但在任何年龄组中SHR和WKY之间均无差异（p>0.05）。SHR从4周龄起肾血管阻力增加（21.5±1.8），显著高于WKY（14.4±0.9 mmHg·ml⁻¹·min·g）（p<0.01），且在老年组中维持在较高水平（p≤0.01）。
在2至10周龄时，麻醉状态下的SHR与WKY相比，RBF、总GFR和分区GFR无显著差异，且在高血压发作期间SHR近髓质皮质的GFR未降低。本研究结果表明，高血压的发展不能用RBF或总GFR及分区GFR的暂时下降来解释。
