Macković-Basić M, Salihagić A, Ries N, Sabolić I
Department of Physiology, Faculty of Medicine, University of Zagreb, Yugoslavia.
Biochem Pharmacol. 1988 May 1;37(9):1699-705. doi: 10.1016/0006-2952(88)90431-5.
The fluorescence quenching of acridine orange was used to compare Na+-H+ exchange and ion conductances in renal cortical brush-border membrane vesicles (BBMV) isolated from euthyroid and hyperthyroid rats. In BBMV from euthyroid animals, Na+-H+ exchange was entirely electroneutral. In BBMV from hyperthyroid rats, the total rates of Na+-H+ exchange were about 30% higher than in BBMV from euthyroid animals. However, the electroneutral exchange in these membranes was similar to that in BBMV from euthyroid rats; the observed increase in exchange was due to electrically coupled Na+ and H+ movements through conductive pathways in the membranes. Ion conductances in isolated BBMV were tested with outwardly directed K+ gradients in the presence of carbonyl cyanide m-chlorophenylhydrazone (K+ conductance) or valinomycin (H+ conductance). The K+ conductance was negligible and similar in BBMV from both groups of rats. A significant H+ conductance was present in both kinds of membrane preparations and was by 37% higher in BBMV from hyperthyroid animals. Therefore, our experiments failed to demonstrate an increased electroneutral Na+-H+ exchange in BBMV from hyperthyroid rats. Instead, a finding of a significant electrically BBMV from hyperthyroid rats. Instead, a finding of a significant electrically coupled Na+-H+ antiport in the presence of increased H+ conductance in BBMV from hyperthyroid rats indicates that these membranes may also have increased Na+ conductance.
利用吖啶橙的荧光猝灭来比较从甲状腺功能正常和甲状腺功能亢进的大鼠分离出的肾皮质刷状缘膜囊泡（BBMV）中的Na⁺-H⁺交换和离子电导。在甲状腺功能正常动物的BBMV中，Na⁺-H⁺交换完全是电中性的。在甲状腺功能亢进大鼠的BBMV中，Na⁺-H⁺交换的总速率比甲状腺功能正常动物的BBMV高约30%。然而，这些膜中的电中性交换与甲状腺功能正常大鼠的BBMV中的相似；观察到的交换增加是由于Na⁺和H⁺通过膜中的传导途径进行电偶联移动。在羰基氰化物间氯苯腙存在下（K⁺电导）或缬氨霉素存在下（H⁺电导），用外向K⁺梯度测试分离的BBMV中的离子电导。两组大鼠的BBMV中的K⁺电导可忽略不计且相似。两种膜制剂中均存在显著的H⁺电导，且甲状腺功能亢进动物的BBMV中的H⁺电导高37%。因此，我们的实验未能证明甲状腺功能亢进大鼠的BBMV中电中性Na⁺-H⁺交换增加。相反，在甲状腺功能亢进大鼠的BBMV中H⁺电导增加的情况下发现显著的电偶联Na⁺-H⁺反向转运，这表明这些膜中的Na⁺电导也可能增加。
