Foreman J W, Wald H, Reynolds R A, Segal S
Biochim Biophys Acta. 1981 Aug 6;646(1):188-92. doi: 10.1016/0005-2736(81)90287-x.
The uptake of amino acids by isolated rat renal brush border membrane vesicles in a modified Krebs-Ringer bicarbonate buffer and a phosphate buffer was compared to the uptake in the standard membrane vesicle buffer, Tris-Hepes-mannitol. The uptake in the modified Krebs-Ringer bicarbonate buffer was similar to that in the Tris-Hepes-mannitol buffer. Removal of the ionic constituents other than NaCl and NaHCO3 in the modified Krebs-Ringer bicarbonate buffer (KCl, CaCl2, KH2PO4 and MgSO4) did not affect the amino acid uptake by the isolated membrane vesicles. The timed uptake of proline under sodium gradient conditions in a phosphate buffer had a markedly dampened overshoot. Kinetic analysis of the initial rate of proline uptake in a phosphate buffer compared to a Tris-Herpes-mannitol buffer showed two entry systems for proline in each buffer with similar Km values, but the maximal rate of transport (V) for each system in the phosphate buffer was much lower than that in the Tris-Hepes-mannitol buffer. From these data, phosphate buffer does not appear to be a suitable medium for the study of amino acid uptake by isolated brush border membrane vesicles.
将分离的大鼠肾刷状缘膜囊泡在改良的 Krebs-Ringer 碳酸氢盐缓冲液和磷酸盐缓冲液中对氨基酸的摄取情况，与在标准膜囊泡缓冲液 Tris-Hepes-甘露醇中的摄取情况进行了比较。在改良的 Krebs-Ringer 碳酸氢盐缓冲液中的摄取情况与在 Tris-Hepes-甘露醇缓冲液中的相似。去除改良的 Krebs-Ringer 碳酸氢盐缓冲液（KCl、CaCl2、KH2PO4 和 MgSO4）中除 NaCl 和 NaHCO3 以外的离子成分，并不影响分离的膜囊泡对氨基酸的摄取。在磷酸盐缓冲液中，在钠梯度条件下脯氨酸的定时摄取有明显减弱的过冲现象。与 Tris-Herpes-甘露醇缓冲液相比，对磷酸盐缓冲液中脯氨酸摄取初始速率的动力学分析表明，每种缓冲液中脯氨酸有两种进入系统，其 Km 值相似，但磷酸盐缓冲液中每个系统的最大转运速率（V）远低于 Tris-Hepes-甘露醇缓冲液中的。根据这些数据，磷酸盐缓冲液似乎不是研究分离的刷状缘膜囊泡摄取氨基酸的合适介质。
