Soleimani M, Bookstein C, Singh G, Rao M C, Chang E B, Bastani B
Department of Medicine, Indiana University, Indianapolis 46202-5116, USA.
J Membr Biol. 1995 Apr;144(3):209-16. doi: 10.1007/BF00236834.
This study examines the effects of acute in vitro acid-base disorders on Na+/H+ and H(+)-ATPase transporters in rabbit kidney proximal tubules (PT). PT suspensions were incubated in solutions with varying acid base conditions for 45 min and utilized for brush border membrane (BBM) vesicles preparation. BBM vesicles were studied for Na+/H+ exchange activity (assayed by 22Na+ influx) or abundance (using NHE-3 specific antibody) and H(+)-ATPase transporter abundance (using antibody against the 31 kDa subunit). The Na+/H+ exchanger activity increased by 55% in metabolic acidosis (pH 6.5, HCO3- 3 mM) and decreased by 41% in metabolic alkalosis (pH 8.0, HCO3- 90 mM). The abundance of NHE-3 remained constant in acidic, control, and alkalotic groups. H(+)-ATPase abundance, however, decreased in metabolic acidosis and increased in metabolic alkalosis by 57% and 42%, respectively. In PT suspensions incubated in isohydric conditions (pH 7.4), Na+/H+ exchanger activity increased by 29% in high HCO3- group (HCO3- 96 mM) and decreased by 16% in the low HCO3- groups (HCO3- 7 mM. The NHE-3 abundance remained constant in high, normal, and low [HCO3-] tubules. The abundance of H(+)-ATPase, however, increased by 82% in high [HCO3-] and decreased by 77% in the low [HCO3-] tubules. In PT suspensions incubated in varying pCO2 and constant [HCO3-], Na+/H+ exchanger activity increased by 35% in high pCO2 (20% pCO2, respiratory acidosis) and decreased by 32% in low pCO2 (1.5% pCO2, respiratory alkalosis) tubules. The NHE-3 abundance remained unchanged in high, normal, and low pCO2 tubules.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究考察了急性体外酸碱紊乱对兔肾近端小管（PT）中Na⁺/H⁺和H⁺-ATP酶转运体的影响。将PT悬浮液置于不同酸碱条件的溶液中孵育45分钟，用于制备刷状缘膜（BBM）小泡。研究BBM小泡的Na⁺/H⁺交换活性（通过²²Na⁺内流测定）或丰度（使用NHE-3特异性抗体）以及H⁺-ATP酶转运体丰度（使用针对31 kDa亚基的抗体）。在代谢性酸中毒（pH 6.5，HCO₃⁻ 3 mM）时，Na⁺/H⁺交换器活性增加55%，在代谢性碱中毒（pH 8.0，HCO₃⁻ 90 mM）时降低41%。在酸性、对照和碱性组中，NHE-3的丰度保持恒定。然而，H⁺-ATP酶丰度在代谢性酸中毒时降低，在代谢性碱中毒时分别增加57%和42%。在等渗条件（pH 7.4）下孵育的PT悬浮液中，高HCO₃⁻组（HCO₃⁻ 96 mM）的Na⁺/H⁺交换器活性增加29%，低HCO₃⁻组（HCO₃⁻ 7 mM）降低16%。在高、正常和低[HCO₃⁻]的小管中，NHE-3丰度保持恒定。然而，H⁺-ATP酶丰度在高[HCO₃⁻]时增加82%，在低[HCO₃⁻]的小管中降低77%。在不同pCO₂和恒定[HCO₃⁻]条件下孵育的PT悬浮液中，高pCO₂（20% pCO₂，呼吸性酸中毒）的小管中Na⁺/H⁺交换器活性增加35%，低pCO₂（1.5% pCO₂，呼吸性碱中毒）的小管中降低32%。在高、正常和低pCO₂的小管中，NHE-3丰度保持不变。（摘要截断于250字）
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