Benyajati S, Johnson J L
Department of Physiology and Biophysics, College of Medicine, University of Oklahoma, Health Sciences Center, Oklahoma City 73190.
Am J Physiol. 1991 May;260(5 Pt 2):R879-88. doi: 10.1152/ajpregu.1991.260.5.R879.
We examined characteristics of taurine transport across renal brush-border membranes (BBM) of the garter snake (Thamnophis sirtalis), a species that demonstrates both net reabsorption and secretion of taurine in vivo. Transport was examined by a rapid filtration technique at 25 degrees C. Inwardly directed Na+ gradient specifically stimulated taurine uptake. Under initial taurine equilibrium condition, a small overshoot of taurine uptake driven by an inwardly directed NaCl gradient could be observed. No stimulation of taurine uptake was observed under Na+ equilibrium or K+, Li+, or choline gradients conditions. Reptilian renal BBM taurine transport also displayed specific Cl- requirement: replacement of NaCl by NaSCN or Na(+)-gluconate gradients inhibited taurine uptake. The uptake was stimulated under Cl- gradient compared with Cl- equilibrium conditions. Taurine transport was not stimulated by H+ gradient in either direction, although it was inhibited by acidic pH (less than 7.0). Amiloride and furosemide had no effects. The transport was electrogenic, stimulated by an inside negative membrane potential, and inhibited by other beta-amino acids. Overall, the reptilian BBM transport system for taurine resembles those observed in both mammalian and fish renal BBM.
我们研究了束带蛇（美洲束带蛇）肾刷状缘膜（BBM）上牛磺酸的转运特性，该物种在体内表现出牛磺酸的净重吸收和分泌。在25摄氏度下通过快速过滤技术检测转运情况。内向的Na⁺梯度特异性刺激牛磺酸摄取。在初始牛磺酸平衡条件下，可观察到由内向的NaCl梯度驱动的牛磺酸摄取有一个小的过冲。在Na⁺平衡或K⁺、Li⁺或胆碱梯度条件下未观察到牛磺酸摄取的刺激。爬行类动物肾BBM牛磺酸转运也表现出对Cl⁻的特异性需求：用NaSCN或Na⁺ - 葡萄糖酸盐梯度替代NaCl会抑制牛磺酸摄取。与Cl⁻平衡条件相比，在Cl⁻梯度下摄取受到刺激。无论H⁺梯度方向如何，牛磺酸转运均未受到刺激，尽管它受到酸性pH（小于7.0）的抑制。氨氯吡咪和呋塞米无作用。该转运是电生性的，受到膜内负电位的刺激，并受到其他β - 氨基酸的抑制。总体而言，爬行类动物BBM牛磺酸转运系统类似于在哺乳动物和鱼类肾BBM中观察到的系统。
