Reuter E
Curr Probl Clin Biochem. 1976;6:416-25.
Tubuli were prepared from rat renal cortex by modification of the method adopted from HOWARD and PESCH (J.Biol. Chem. 243, 3105, 1968). At 37 degrees C tubuli showed constant pyruvate consumption and glucose production for more than one hour. Intracellular electrolyte and amino acid concentrations were measured after separating the tubuli from the incubation medium by a layer of silicon oil in 5 seconds. During incubation at 37 degrees C L-alanine was accumulated 2.6 fold in the tubuli, while intracellular Na+ concentration dropped to about 50 mEq/l. At 27 degrees C, when pyruvate consumption and glucose production was reduced to less than half compared with 37 degrees C incubation, the respective gradients were higher. L-alanine accumulation was reduced by 2,4-dinitrophenol, antimycin A, ouabain and p-hydroxymercuribenzoate and was completely abolished by the reversal of the Na+ concentration gradient between extracellular and intracellular spaces. At 4 degrees C, when erergy production in tubuli ceased, L-alanine could be concentrated in the case of a Na+o/Na+i ratio greater than unity but not at a lower ratio. It is concluded that the accumulation of L-alanine is a direct function of the energy provided by the Na+ concentration gradient and is mediated by a postulated carrier, which can be injured by sulfhydryl group reagents like p-hydroxymercuribenzoate.
肾小管是通过对霍华德和佩施（《生物化学杂志》243卷，3105页，1968年）所采用方法进行改进后，从大鼠肾皮质制备而来。在37℃时，肾小管在一个多小时内丙酮酸消耗量和葡萄糖生成量保持恒定。通过在5秒内用一层硅油将肾小管与孵育培养基分离后，测量细胞内电解质和氨基酸浓度。在37℃孵育期间，L-丙氨酸在肾小管中积累了2.6倍，而细胞内Na⁺浓度降至约50 mEq/L。在27℃时，与37℃孵育相比，丙酮酸消耗量和葡萄糖生成量减少至不到一半，相应的梯度更高。L-丙氨酸的积累被2,4-二硝基苯酚、抗霉素A、哇巴因和对羟基汞苯甲酸抑制，并且通过细胞外和细胞内空间之间Na⁺浓度梯度的逆转而完全消除。在4℃时，当肾小管中的能量产生停止时，如果Na⁺o/Na⁺i比值大于1，L-丙氨酸可以被浓缩，但在较低比值时则不能。得出的结论是，L-丙氨酸的积累是由Na⁺浓度梯度提供的能量的直接函数，并且由一种假定的载体介导，该载体可被对羟基汞苯甲酸等巯基试剂损伤。
