Rehm W S, Carrasquer G, Schwartz M
University of Louisville, Kentucky.
J Intern Med Suppl. 1990;732:31-9. doi: 10.1111/j.1365-2796.1990.tb01469.x.
The neutral proton pump (NP) model postulates a neutral exchange of K+ for H+ across the secretory membrane and the electrogenic proton pump (EP) model an electrogenic proton pump. Previous evidence is briefly reviewed and polarization of EMFs by transmucosal voltage clamping (VC) is presented. During VC, open circuit potential difference (PD) (VOC) is obtained by breaking the circuit for 2 s (after dielectric capacitors have discharged). The magnitude of polarization in Cl- media is less than in Cl(-)-free media, presumably due to the high conductance of Cl- paths. The magnitude in Cl(-)-free media is from 35 to 50 mV for a VC of 100 mV (nutrient side positive). The Na+/K(+)-ATPase is not essential because with choline sulphate media polarization is typical. With Cl(-)-free media, VOC versus IH (H+ rate) is exponential but (VC-VOC) versus IH is linear. Polarization on the basis of the NP model would be due to changes in K+ diffusion potentials. However, with 80 mM K+ on both sides (Cl(-)-free media) polarization is typical. We conclude that polarization cannot be due to a change in K+ diffusion potentials but to polarization of the EP model. The problem remains of how to incorporate the important finding of the H+/K(+)-ATPase into a model for the intact tissue.
中性质子泵（NP）模型假定钾离子（K⁺）与氢离子（H⁺）通过分泌膜进行中性交换，而电生性质子泵（EP）模型则假定存在电生性质子泵。本文简要回顾了先前的证据，并介绍了通过跨黏膜电压钳制（VC）对电动势进行极化的情况。在电压钳制过程中，通过断开电路2秒（在介电电容器放电后）来获得开路电位差（PD）（VOC）。在含氯离子（Cl⁻）的介质中极化幅度小于无Cl⁻介质中的幅度，这可能是由于Cl⁻通道的高电导率所致。对于100 mV的电压钳制（营养侧为正），无Cl⁻介质中的极化幅度为35至50 mV。钠钾ATP酶并非必需，因为在硫酸胆碱介质中极化是典型的。在无Cl⁻介质中，VOC与氢离子流率（IH）（H⁺速率）的关系呈指数关系，但（VC - VOC）与IH的关系呈线性关系。基于NP模型的极化可能是由于K⁺扩散电位的变化。然而，在两侧均为80 mM钾离子的情况下（无Cl⁻介质），极化是典型的。我们得出结论，极化并非由于K⁺扩散电位的变化，而是由于EP模型的极化。如何将氢离子/钾离子ATP酶的这一重要发现纳入完整组织的模型中，问题依然存在。
