Peterson L N
Kidney Int. 1984 Jun;25(6):899-905. doi: 10.1038/ki.1984.107.
Renal concentrating ability becomes impaired after approximately 2 weeks of dietary potassium (K) depletion in the rat. Since inner medullary plasma flow (IMPF) has been shown to be reduced after 3 weeks of K-depletion, IMPF was measured after 2 and 3 weeks of dietary K-deprivation to determine if the change in IMPF is present at the time the renal concentrating defect first appears. In the present study, similar reductions in maximal urine concentration were present in rats K-depleted for 2 and 3 weeks. IMPF measured by the 125I albumin accumulation method, however, was normal after 2 weeks of K-depletion (control, 35.1 +/- 1.93 vs. K-depletion 2 weeks, 32.8 +/- 1.52 ml/min/100 g IM), and was reduced after 3 weeks of this dietary regime (K-depletion, 3 weeks: 13.8 +/- 1.84). To determine the mechanism of the decrease in IMPF after 3 weeks of K-depletion, rats were treated acutely with indomethacin. There was no significant change in IMPF in control or 3-week K-depleted rats following treatment with indomethacin. These results suggest that the reduction in medullary solute content after 2 weeks of K-depletion cannot be attributed to a reduction in IMPF. In addition, products of the cyclooxygenase enzyme systems do not appear to contribute in a major way to the reduction in IMPF measured after 3 weeks of dietary K-depletion.
在大鼠中，膳食钾（K）缺乏约2周后，肾脏浓缩能力受损。由于已表明缺钾3周后髓质内血浆流量（IMPF）会降低，因此在膳食缺钾2周和3周后测量IMPF，以确定在肾脏浓缩缺陷首次出现时IMPF是否发生变化。在本研究中，缺钾2周和3周的大鼠最大尿浓缩程度有类似降低。然而，用125I白蛋白蓄积法测量的IMPF在缺钾2周后是正常的（对照组，35.1±1.93 vs. 缺钾2周，32.8±1.52 ml/min/100 g髓质），而在这种饮食方案3周后降低（缺钾3周：13.8±1.84）。为了确定缺钾3周后IMPF降低的机制，给大鼠急性注射吲哚美辛进行治疗。注射吲哚美辛后，对照组或缺钾3周的大鼠IMPF没有显著变化。这些结果表明，缺钾2周后髓质溶质含量的降低不能归因于IMPF的降低。此外，环氧化酶系统的产物似乎对膳食缺钾3周后测量的IMPF降低没有主要作用。
