Orlando R C, Tobey N A, Schreiner V J, Readling R D
Department of Medicine, University of North Carolina School of Medicine, Chapel Hill 27514.
Am J Physiol. 1988 Sep;255(3 Pt 1):G286-91. doi: 10.1152/ajpgi.1988.255.3.G286.
The transmural electrical potential difference (PD) was measured in vivo across the buccal mucosa of humans and experimental animals. Mean PD was -31 +/- 2 mV in humans, -34 +/- 2 mV in dogs, -39 +/- 2 mV in rabbits, and -18 +/- 1 mV in hamsters. The mechanisms responsible for this PD were explored in Ussing chambers using dog buccal mucosa. After equilibration, mean PD was -16 +/- 2 mV, short-circuit current (Isc) was 15 +/- 1 microA/cm2, and resistance was 1,090 +/- 100 omega.cm2, the latter indicating an electrically "tight" tissue. Fluxes of [14C]mannitol, a marker of paracellular permeability, varied directly with tissue conductance. The net fluxes of 22Na and 36Cl were +0.21 +/- 0.05 and -0.04 +/- 0.02 mueq/h.cm2, respectively, but only the Na+ flux differed significantly from zero. Isc was reduced by luminal amiloride, serosal ouabain, or by reducing luminal Na+ below 20 mM. This indicated that the Isc was determined primarily by active Na+ absorption and that Na+ traverses the apical membrane at least partly through amiloride-sensitive channels and exits across the basolateral membrane through Na+-K+-ATPase activity. We conclude that buccal mucosa is capable of active electrolyte transport and that this capacity contributes to generation of the buccal PD in vivo.
在人和实验动物体内测量了跨颊黏膜的跨壁电位差（PD）。人类的平均PD为-31±2 mV，犬为-34±2 mV，兔为-39±2 mV，仓鼠为-18±1 mV。利用犬颊黏膜在尤斯灌流小室中探究了产生这种PD的机制。平衡后，平均PD为-16±2 mV，短路电流（Isc）为15±1 μA/cm²，电阻为1090±100 Ω·cm²，后者表明该组织电“紧密”。作为细胞旁通透性标志物的[¹⁴C]甘露醇通量与组织电导率直接相关。²²Na和³⁶Cl的净通量分别为+0.21±0.05和-0.04±0.02 μeq/h·cm²，但只有Na⁺通量与零有显著差异。管腔面施加氨氯吡脒、浆膜面施加哇巴因或使管腔面Na⁺浓度降至20 mM以下均可使Isc降低。这表明Isc主要由Na⁺的主动吸收决定，且Na⁺至少部分通过氨氯吡脒敏感通道穿过顶端膜，并通过Na⁺-K⁺-ATP酶活性从基底外侧膜排出。我们得出结论，颊黏膜能够进行主动电解质转运，且这种能力有助于体内颊部PD的产生。
