Gerencser G A
Am J Physiol. 1983 Mar;244(3):R412-7. doi: 10.1152/ajpregu.1983.244.3.R412.
Microelectrodes were used to measure the potential difference (psi m) across the mucosal membrane of epithelial cells lining the villi of isolated Aplysia californica intestine. In substrate-free NaCl seawater medium psi m was -55.1 +/- 1.2 mV. The cell interior was negative relative to the mucosal bathing solution. Intracellular K+ activity, determined in the absorptive cells with single-barreled liquid ion-exchanger microelectrodes, was 383 +/- 15 mM. Since the calculated K+ equilibrium potential exceeds the membrane potential, K+ is accumulated by the intestinal absorptive cell. Intracellular Na+ activity (aiNa) was also determined in the intestinal cells of Aplysia with single-barreled liquid ion-exchanger microelectrodes and was 17.2 +/- 2.5 mM. aiNa was much less than that predicted by the electrochemical equilibrium value for Na+ across the mucosal membrane. From these data the steady-state transapical Na+ and K+ electrochemical potential differences were calculated. Serosal ouabain abolished net sodium absorption as determined by flux measurements. These results are consistent with the operation of a basolateral Na+ - K+ pump.
使用微电极测量分离的加州海兔肠道绒毛上皮细胞黏膜膜上的电位差（ψm）。在无底物的NaCl海水培养基中，ψm为-55.1±1.2 mV。细胞内部相对于黏膜浴液呈负电。用单管液体离子交换微电极在吸收细胞中测定的细胞内K⁺活性为383±15 mM。由于计算出的K⁺平衡电位超过膜电位，K⁺被肠道吸收细胞积累。还用单管液体离子交换微电极在海兔的肠道细胞中测定了细胞内Na⁺活性（aiNa），为17.2±2.5 mM。aiNa远低于跨黏膜膜的Na⁺电化学平衡值预测的值。根据这些数据计算了稳态经顶端Na⁺和K⁺的电化学电位差。通量测量表明，浆膜哇巴因消除了净钠吸收。这些结果与基底外侧Na⁺-K⁺泵的运作一致。
