Foulkes E C
Am J Physiol. 1985 Dec;249(6 Pt 2):F878-83. doi: 10.1152/ajprenal.1985.249.6.F878.
Estimates were obtained both with a rapid-transient technique and under steady-state conditions of the average time required for filtered solutes in the intact rabbit kidney to cross tubular epithelium from tubular lumen into the peritubular inulin space. This interval, defined as the transepithelial passage time, was relatively short (about 15 s) for glucose, in agreement with earlier results in the dog. In contrast, several amino acids required an average transepithelial passage time of about 40 s. Values for aspartate could only be obtained when its large basolateral uptake was inhibited by excess succinate. The long transepithelial passage time may be due to the slow extrusion of reabsorbed amino acids across basolateral cell membranes. This hypothesis was supported by the extent of tissue accumulation of amino acids during reabsorption. Even though basolateral transfer may thus limit the linear rate of movement of filtered amino acids across the epithelium, the step determining fractional absorption from the lumen is situated at the brush border.
采用快速瞬态技术和稳态条件，对完整兔肾中滤过溶质从肾小管腔穿过肾小管上皮进入肾小管周菊粉间隙所需的平均时间进行了估算。这一间隔时间，即跨上皮转运时间，对于葡萄糖来说相对较短（约15秒），这与早期在狗身上得到的结果一致。相比之下，几种氨基酸的平均跨上皮转运时间约为40秒。只有当过量琥珀酸盐抑制天冬氨酸的大量基底外侧摄取时，才能获得其数值。较长的跨上皮转运时间可能是由于重吸收的氨基酸跨基底外侧细胞膜的缓慢排出所致。重吸收过程中氨基酸在组织中的积累程度支持了这一假说。尽管基底外侧转运可能因此限制了滤过氨基酸跨上皮的线性移动速率，但决定从管腔中分数吸收的步骤位于刷状缘。
