Luminal and basolateral surface membranes of secretory acinar cells: electrophysiological comparison of cationic sensitivities.
Luminal and basolateral surface membranes of secretory acinar cells: electrophysiological comparison of cationic sensitivities.
复制标题
分泌性腺泡细胞的管腔和基底外侧表面膜：阳离子敏感性的电生理学比较。
DOI：
10.1002/jez.1402360305
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Orkand,PM
中科院分区：
文献类型：
--
作者：
Senseman,DM;Horwitz,IS;Cleemann,L;Orkand,PM
使用水生蜗牛 Helisoma trivolvis 的管腔灌注和外部灌注唾液腺比较分泌性腺泡细胞的管腔和基底外侧膜表面的阳离子敏感性（K+、Na+ 和 Ca2+）。在腺泡腔附近观察到界定两个膜表面的紧密连接，表明暴露于灌注溶液的总膜面积超过了与腔灌注溶液接触的总膜面积。发现腺泡细胞的静息膜电位取决于外部灌注溶液和腔灌注溶液中的 K+ 浓度。任一膜表面的单侧 K+ 升高都会导致腺泡细胞快速且持续的去极化。对于给定的 K+ 浓度，基底外侧表面 K+ 抬高产生的去极化水平显着高于管腔表面。在两个膜表面同时 K+ 升高后，观察到最高水平的膜去极化。腺泡细胞响应电场刺激而产生过调动作电位的能力取决于 Na+ 和 Ca2+。在双边去除任一阳离子后，总是会发生完全阻断。单方面去除 Na+ 或 Ca2+ 的效果被证明是有些可变的。一般来说，单侧去除 Na+ 比去除 Ca2+ 更能有效地降低再生反应，而从基底外侧表面去除任一阳离子比去除管腔表面更能有效地降低再生反应。在任一膜表面单侧应用 Ca2+ 拮抗剂镉 (Cd2+) 也可以阻断腺泡细胞中的电诱发动作电位。然而，当应用于管腔时，需要比应用于基底外侧腺体表面更高的 Cd2+ 浓度来实现完全阻断。该结果未能支持电压敏感 Ca2+ 通道在该制剂中空间限制于管腔细胞表面的假设。
Cation sensitivities (K+, Na+, and Ca2+) of luminal and basolateral membrane surfaces of secretory acinar cells were compared using a luminally perfused and externally superfused salivary gland from the aquatic snail,Helisoma trivolvis. Tight junctions delimiting the two membrane surfaces were observed near the acinar lumen suggesting that the total membrane area exposed to the superfusion solution exceeded that in contact with the luminal perfusion solution.The resting membrane potential of acinar cells was found to be dependent upon the K+concentration in both the external superfusion and the luminal perfusion solutions. Unilateral K+elevation at either membrane surface produced a rapid and sustained depolarization of the acinar cell. For a given K+concentration, the level of depolarization produced by K+elevation at the basolateral surface was significantly higher than at the luminal surface. The highest level of membrane depolarization was observed following simultaneous K+elevation at both membrane surfaces.The ability of acinar cells to generate overshooting action potentials in response to electrical field stimulation was dependent upon both Na+and Ca2+.Complete blockade invariably occurred following bilateral removal of either cation. The effects of unilateral removal of either Na+or Ca2+proved to be somewhat variable. In general, unilateral removal of Na+was more effective in reducing the regenerative response than Ca2+while removal of either cation from the basolateral surface was more effective in reducing the regenerative response than its removal from the luminal surface.Electrically evoked action potentials in acinar cells could also be blocked with unilateral application of the Ca2+antagonist, cadmium (Cd2+), at either membrane surface. However, higher Cd2+concentrations were required to achieve complete blockade when applied to the luminal than to the basolateral gland surface. This result fails to support a hypothesis of voltage‐sensitive Ca2+channels being spatially restricted to the luminal cell surface in this preparation.