Harris S I, Patton L, Barrett L, Mandel L J
J Biol Chem. 1982 Jun 25;257(12):6996-7002.
The kinetics of oxygen consumption and (Na+,K+)-ATPase-mediated K+ transport was examined by reintroducing K+ into a K+-depleted suspension of renal tubules. In the presence of the substrates glucose, lactate, and alanine, a K+/O2 ratio of 10.4 +/- 0.2 was obtained, and the apparent K1/2 for K+ transport with respect to external K+ concentration was 0.9 mM. Supplementation of the substrates with the short chain fatty acid, butyric, had a 3-fold effect on the kinetic parameters examined: 1) the quantity of (Na+,K+)-ATPase-mediated ion transport per oxygen consumed fell by 17 +/- 2%; 2) the maximum rate of K+ transport increased by nearly 50%; and 3) the apparent K1/2 for transport with respect to external K+ concentration rose to 1.5 mM. These results indicate that despite decreasing the quantity of ATP produced per oxygen consumed, short chain fatty acids are able to increase the overall production of ATP during periods of high metabolic demand. The coupling between the two major metabolic processes of the renal cell, (Na+,K+)-ATPase-mediated ion transport and mitochondrial oxidative phosphorylation, is addressed in the context of these findings.
通过将钾离子重新引入低钾的肾小管悬浮液中，研究了氧消耗动力学和（钠+，钾+）-ATP酶介导的钾离子转运。在存在底物葡萄糖、乳酸和丙氨酸的情况下，获得了10.4±0.2的钾离子/氧比值，并且相对于外部钾离子浓度，钾离子转运的表观K1/2为0.9 mM。用短链脂肪酸丁酸补充底物对所检测的动力学参数有三倍的影响：1）每消耗一分子氧，（钠+，钾+）-ATP酶介导的离子转运量下降了17±2%；2）钾离子转运的最大速率增加了近50%；3）相对于外部钾离子浓度，转运的表观K1/2升至1.5 mM。这些结果表明，尽管每消耗一分子氧产生的三磷酸腺苷（ATP）量减少，但在高代谢需求期间，短链脂肪酸能够增加ATP的总体产生量。在这些研究结果的背景下，探讨了肾细胞的两个主要代谢过程，即（钠+，钾+）-ATP酶介导的离子转运和线粒体氧化磷酸化之间的偶联。
