Brazy P C, Mandel L J, Gullans S R, Soltoff S P
Am J Physiol. 1984 Oct;247(4 Pt 2):F575-81. doi: 10.1152/ajprenal.1984.247.4.F575.
These studies examine the phosphate dependence of fluid absorption and oxidative metabolism in proximal tubules from rabbit kidney. Removal of inorganic phosphate from intraluminal fluid in isolated perfused tubules reduced fluid absorption (Jv) from 1.0 nl X mm-1 X min-1 to zero and removal of phosphate from the medium bathing tubules in suspension reduced O2 consumption rates (coupled, uncoupled, ouabain sensitive, and ouabain insensitive) and ATP contents by 30-40%. Inhibitions induced by removal of phosphate could be altered by addition of selected organic substrates to ambient fluids. Addition of succinate, citrate, or malate preserved uncoupled respiration and partially preserved Jv (0.4-0.9 nl X mm-1 X min-1), with succinate being most effective. Addition of short-chain fatty acids (butyrate or valerate) to phosphate-free media had little or no effect on Jv. n-Butylmalonate, an inhibitor of dicarboxylate anion transport into mitochondria, reduced oxidative metabolism, ATP content, and Jv when added to phosphate-containing media but had no further effect on these tubular functions when added to phosphate-free media. Together these results suggest that phosphate limitation reduces dicarboxylate anion availability to mitochondria and that this inhibition may contribute to the overall reduction in oxidative metabolism and Jv observed under these conditions.
这些研究考察了兔肾近端小管中液体吸收和氧化代谢对磷酸盐的依赖性。在分离的灌注小管中，去除管腔内液体中的无机磷酸盐可使液体吸收（Jv）从1.0 nl×mm⁻¹×min⁻¹降至零，而在悬浮状态下去除小管浴液中的磷酸盐可使耗氧率（偶联、解偶联、哇巴因敏感和哇巴因不敏感）和ATP含量降低30 - 40%。去除磷酸盐所诱导的抑制作用可通过向周围液体中添加特定有机底物而改变。添加琥珀酸、柠檬酸或苹果酸可维持解偶联呼吸，并部分维持Jv（0.4 - 0.9 nl×mm⁻¹×min⁻¹），其中琥珀酸最为有效。向无磷酸盐培养基中添加短链脂肪酸（丁酸或戊酸）对Jv几乎没有影响。二羧酸阴离子转运至线粒体的抑制剂正丁基丙二酸，添加到含磷酸盐培养基中时会降低氧化代谢、ATP含量和Jv，但添加到无磷酸盐培养基中时对这些小管功能没有进一步影响。这些结果共同表明，磷酸盐限制会降低线粒体中二羧酸阴离子的可用性，这种抑制作用可能是导致在这些条件下观察到的氧化代谢和Jv总体降低的原因。
