Gaudio K M, Thulin G, Siegel N J
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520-8064, USA.
Pediatr Res. 1996 Sep;40(3):457-61. doi: 10.1203/00006450-199609000-00015.
We have previously shown that the immature tubule is tolerant of prolonged anoxia. In addition, cellular ATP is maintained at 2-fold higher levels during anoxia in the immature tubules compared with the mature tubules. The purpose of this study was: 1) to determine whether anaerobic glycolysis contributes to the tolerance to anoxia and preservation of cellular ATP in immature tubules and 2) to evaluate whether the tolerance demonstrated by immature tubules is dependent on preservation of cellular ATP. Suspensions of proximal tubules from immature (8-10 d) and mature (8-10 wk) rats were subjected to 15 and 45 min of anoxia in a standard buffer and in buffers designed to inhibit glycolysis. Lactate dehydrogenase release was used to assess plasma membrane damage, ATP levels were determined as an index of cellular energy and total lactate production was measured to evaluate glycolytic activity. After 45 min of anoxia, total lactate production was less in immature tubules (101 +/- 48 micrograms of lactate/mg of DNA) compared with mature tubules (148 +/- 36 micrograms of lactate/mg of DNA). After inhibition of glycolytic metabolism, ATP decreased to similar levels in both immature and mature tubules. However, immature tubules remained resistant to anoxic damage (lactate dehydrogenase: mature tubules 38 +/- 4%, immature tubules 29 +/- 1.0%). Therefore, enhanced glycolytic activity does not play a dominant role in the tolerance of the developing kidney to anoxia, and this tolerance is not primarily dependent on preservation of cellular ATP.
我们之前已经表明，未成熟肾小管对长时间缺氧具有耐受性。此外，与成熟肾小管相比，未成熟肾小管在缺氧期间细胞ATP水平维持在高2倍的水平。本研究的目的是：1）确定无氧糖酵解是否有助于未成熟肾小管对缺氧的耐受性及细胞ATP的保存；2）评估未成熟肾小管所表现出的耐受性是否依赖于细胞ATP的保存。将来自未成熟（8 - 10日龄）和成熟（8 - 10周龄）大鼠的近端肾小管悬浮液，在标准缓冲液和旨在抑制糖酵解的缓冲液中进行15分钟和45分钟的缺氧处理。用乳酸脱氢酶释放来评估质膜损伤，测定ATP水平作为细胞能量指标，并测量总乳酸生成以评估糖酵解活性。缺氧45分钟后，与成熟肾小管（148±36微克乳酸/毫克DNA）相比，未成熟肾小管的总乳酸生成较少（101±48微克乳酸/毫克DNA）。抑制糖酵解代谢后，未成熟和成熟肾小管中的ATP均降至相似水平。然而，未成熟肾小管对缺氧损伤仍具有抗性（乳酸脱氢酶：成熟肾小管38±4%，未成熟肾小管29±1.0%）。因此，增强的糖酵解活性在发育中的肾脏对缺氧的耐受性中不发挥主导作用，且这种耐受性并非主要依赖于细胞ATP的保存。
