Ottosen P D, Madsen K M, Bode F, Baumann K, Maunsbach A B
Ren Physiol. 1985;8(2):90-9. doi: 10.1159/000173040.
The effects of basic and neutral amino acids on the reabsorption of 125I-lysozyme by the renal proximal tubule were examined in rats. In whole animal experiments control animals were given an intravenous (i.v.) injection of 125I-lysozyme alone while experimental animals received an i.v. injection of either a basic or a neutral amino acid prior to the injection of 125I-lysozyme. In control animals the renal content of 125I-lysozyme 30 min after injection was 35% of the injected dose. After injection of basic amino acids there was a significant decrease in the renal uptake of lysozyme. There was no effect of neutral amino acids on the reabsorption of lysozyme. In microperfusion experiments proximal convoluted tubules were perfused in vivo for 3 min with a solution containing 125I-lysozyme and either lysine or alanine. In tubules perfused with lysine there was a significant decrease in the reabsorption of lysozyme, whereas alanine had no effect on lysozyme uptake. Electron microscope autoradiography revealed that lysozyme was located in endocytic vesicles and lysosomes in both experimental groups. However, the autoradiographic grain density was significantly decreased in tubules perfused with lysine as compared with those perfused with alanine. These findings demonstrate that basic amino acids inhibit the reabsorption of the cationic protein lysozyme by the proximal tubule cells.
在大鼠身上研究了碱性和中性氨基酸对肾近端小管重吸收¹²⁵I-溶菌酶的影响。在整体动物实验中，对照动物仅静脉注射¹²⁵I-溶菌酶，而实验动物在注射¹²⁵I-溶菌酶之前先静脉注射一种碱性或中性氨基酸。在对照动物中，注射后30分钟¹²⁵I-溶菌酶的肾含量为注射剂量的35%。注射碱性氨基酸后，溶菌酶的肾摄取量显著降低。中性氨基酸对溶菌酶的重吸收没有影响。在微灌注实验中，用含有¹²⁵I-溶菌酶和赖氨酸或丙氨酸的溶液对体内的近端曲管进行3分钟的灌注。在灌注赖氨酸的小管中，溶菌酶的重吸收显著降低，而丙氨酸对溶菌酶的摄取没有影响。电子显微镜放射自显影显示，在两个实验组中溶菌酶都位于内吞小泡和溶酶体中。然而，与灌注丙氨酸的小管相比，灌注赖氨酸的小管放射自显影颗粒密度显著降低。这些发现表明，碱性氨基酸抑制近端小管细胞对阳离子蛋白溶菌酶的重吸收。
