Tessitore N, Sakhrani L M, Massry S G
Am J Physiol. 1986 Jul;251(1 Pt 1):C120-7. doi: 10.1152/ajpcell.1986.251.1.C120.
We investigated the quantitative relationship between cellular ATP concentration and Na+-K+-ATPase activity as measured by ouabain-sensitive 86Rb influx in rabbit proximal renal cells. Cellular ATP was reduced in a stepwise manner by rotenone (10(-7) to 10(-5) M) and was increased by 10 mM adenosine. During these maneuvers, ouabain-sensitive 86Rb influx was linearly related to cellular ATP and did not saturate up to 9.9 mM ATP. In contrast, Na+-K+-ATPase activity in membranes prepared from these cells saturated at 2.0 mM ATP at various sodium (10-100 mM) and potassium (4-100 mM) concentrations. Sodium-dependent phosphate uptake and alpha-methylglucoside (alpha-MG) uptake were both inhibited to a similar degree when cellular ATP was reduced. We conclude that 1) the ATP requirement for saturation of Na+-K+-ATPase is higher in intact renal cells than in the membranes, and 2) the uptake of phosphate and alpha-MG are similarly influenced by reduction in ATP. This effect of ATP on phosphate and AMG uptake is most likely an indirect one and is secondary to changes in the sodium gradient across the cell.
我们研究了兔近端肾细胞中细胞ATP浓度与通过哇巴因敏感的⁸⁶Rb内流所测量的Na⁺-K⁺-ATP酶活性之间的定量关系。用鱼藤酮（10⁻⁷至10⁻⁵M）逐步降低细胞ATP水平，并通过10 mM腺苷使其升高。在这些操作过程中，哇巴因敏感的⁸⁶Rb内流与细胞ATP呈线性相关，并且在高达9.9 mM ATP时未达到饱和。相反，从这些细胞制备的膜中的Na⁺-K⁺-ATP酶活性在各种钠（10 - 100 mM）和钾（4 - 100 mM）浓度下，在2.0 mM ATP时达到饱和。当细胞ATP降低时，钠依赖性磷酸盐摄取和α-甲基葡糖苷（α-MG）摄取均受到相似程度的抑制。我们得出结论：1）完整肾细胞中使Na⁺-K⁺-ATP酶饱和所需的ATP高于膜中的ATP；2）ATP降低对磷酸盐和α-MG摄取的影响相似。ATP对磷酸盐和α-MG摄取的这种作用很可能是间接的，并且是细胞跨膜钠梯度变化的继发效应。
