蛙肾稀释段氢离子转运机制
Mechanism of hydrogen ion transport in the diluting segment of frog kidney.
作者信息
Oberleithner H, Lang F, Messner G, Wang W
出版信息
Pflugers Arch. 1984 Nov;402(3):272-80. doi: 10.1007/BF00585510.
Transepithelial H+ transport was studied in diluting segments of the isolated-perfused kidney of rana esculenta. The experiments were performed in controls as well as in K+-adapted and Na+-adapted animals (exposed to 50 mmol/l KCl or NaCl, resp. for at least 3 days). Conventional and single-barreled, liquid ion-exchanger H+-sensitive microelectrodes were applied in the tubule lumen to evaluate transepithelial H+ net flux (JHte) as well as limiting transepithelial electrical and H+ electrochemical potential differences (PDte, EHte) and luminal pH at zero net flux conditions. The measurements were made in absence (control) and presence of furosemide (5 X 10(-5) mol/l) or amiloride (10(-3) mol/l). EHte (lumen positive vs ground) was 19 +/- 3 mV in controls, 43 +/- 3 mV in K+ adapted but about zero in Na+ adapted animals. Using the corresponding PDte-values, steady state luminal pH of 7.63 +/- 0.05, 7.13 +/- 0.05 and 8.02 +/- 0.02 was calculated for the respective groups of animals (peritubular pH 7.80). In parallel, significant secretory JHte (from blood to lumen) was found in controls (14 +/- 2 pmol X cm-2 X s-1) which was stimulated by K+ adaptation (61 +/- 8 pmol X cm-2 X s-1) but reversed in direction by Na+-adaptation (-8 +/- 1 pmol X cm-2 X s-1). Amiloride inhibited secretory JHte.(ABSTRACT TRUNCATED AT 250 WORDS)
在食用蛙离体灌注肾的稀释段研究了跨上皮H⁺转运。实验在对照组以及适应K⁺和适应Na⁺的动物中进行（分别暴露于50 mmol/l KCl或NaCl至少3天）。在肾小管腔中应用传统的和单管的、液体离子交换H⁺敏感微电极来评估跨上皮H⁺净通量（JHte）以及极限跨上皮电和H⁺电化学势差（PDte，EHte）以及零净通量条件下的管腔pH。测量是在不存在（对照）和存在呋塞米（5×10⁻⁵ mol/l）或氨氯地平（10⁻³ mol/l）的情况下进行的。对照组中EHte（管腔相对于地为正）为19±3 mV，适应K⁺的动物中为43±3 mV，但适应Na⁺的动物中约为零。利用相应的PDte值，计算出各组动物的稳态管腔pH分别为7.63±0.05、7.13±0.05和8.02±0.02（肾小管周pH为7.80）。同时，在对照组中发现有显著的分泌性JHte（从血液到管腔）（14±2 pmol·cm⁻²·s⁻¹），其受到K⁺适应的刺激（61±8 pmol·cm⁻²·s⁻¹），但在Na⁺适应时方向逆转（-8±1 pmol·cm⁻²·s⁻¹）。氨氯地平抑制分泌性JHte。（摘要截断于250字）
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