Burckhardt B C, Frömter E
Pflugers Arch. 1987 Jun;409(1-2):132-7. doi: 10.1007/BF00584760.
Membrane potentials and intracellular pH were measured on rat renal proximal tubular cells in vivo to test whether sodium-bicarbonate cotransport across the peritubular cell membrane accepts OH- (or H+ in opposite direction) or whether it requires the CO2, HCO3-, CO3= buffer to operate. It was found that step changes of peritubular pH in nominally HCO3(-)-free and CO2-free solutions produced qualitatively similar initial potential responses and cell pH responses as changes in peritubular HCO3- concentrations. These responses, however, were considerably smaller and they were neither reduced in Na+-free solutions nor inhibited by the stilbene derivative SITS which is known to block Na+ (HCO3-)n cotransport completely. We conclude that the cotransporter requires the CO2, HCO3-, CO3= buffer for its physiological operation but that high rates of OH- or H+ can also be transferred across the peritubular cell membrane in HCO3(-)-free solutions, probably through a separate transport system.
在大鼠肾近端小管细胞上进行体内膜电位和细胞内pH值测量，以测试碳酸氢钠协同转运体跨肾小管周细胞膜转运时是接受OH⁻（或反向转运H⁺），还是需要CO₂、HCO₃⁻、CO₃²⁻缓冲体系来发挥作用。研究发现，在名义上不含HCO₃⁻和CO₂的溶液中，肾小管周pH值的阶跃变化所产生的初始电位反应和细胞pH反应，在性质上与肾小管周HCO₃⁻浓度变化时相似。然而，这些反应要小得多，且在无Na⁺溶液中不会减弱，也不会被已知能完全阻断Na⁺（HCO₃⁻）ₙ协同转运的芪衍生物SITS抑制。我们得出结论，协同转运体在生理运作时需要CO₂、HCO₃⁻、CO₃²⁻缓冲体系，但在不含HCO₃⁻的溶液中，高浓度的OH⁻或H⁺也可能通过一个独立的转运系统跨肾小管周细胞膜转运。
