Stoddard J S, Reuss L
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550.
J Membr Biol. 1988 May;102(2):163-74. doi: 10.1007/BF01870454.
The effects of bathing solution HCO3-/CO2 concentrations on baseline cell membrane voltages and resistances were measured in Necturus gallbladder epithelium with conventional intracellular microelectrode techniques. Gallbladders were bathed in either low HCO3-/CO2 Ringer's solutions (2.4 mM HCO3-/air or 1 mM HEPES/air) or a high HCO3-/CO2 Ringer's (10 mM HCO3-/1% CO2). The principal finding of these studies was that the apical membrane fractional resistance (fRa) was higher in tissues bathed in the 10 mM HCO3-/CO2 Ringer's, averaging 0.87 +/- 0.06, whereas fRa averaged 0.63 +/- 0.07 and 0.48 +/- 0.08 in 2.4 mM HCO3- and 1 mM HEPES, respectively. Intraepithelial cable analysis was employed to obtain estimates of the individual apical (Ra) and basolateral membrane (Rb) resistances in tissues bathed in 10 mM HCO3-/1% CO2 Ringer's. Compared to previous resistance measurements obtained in tissues bathed in a low HCO3-/CO2 Ringer's, the higher value of fRa was found to be due to both an increase in Ra and a decrease in Rb. The higher values of fRa and lower values of Rb confirm the recent observations of others. To ascertain the pathways responsible for these effects, cell membrane voltages were measured during serosal solution K+ and Cl- substitutions. The results of these studies suggest that an electrodiffusive Cl- transport mechanism exists at the basolateral membrane of tissues bathed in a 10 mM HCO3-/1% CO2 Ringer's, which can explain in part the fall in Rb. The above observations are discussed in terms of a stimulatory effect of solution [HCO3-]/PCO2 on transepithelial fluid transport, which results in adaptive changes in the conductive properties of the apical and basolateral membranes.
采用传统的细胞内微电极技术，在美西螈胆囊上皮中测量了沐浴液中HCO3-/CO2浓度对基线细胞膜电压和电阻的影响。胆囊分别置于低HCO3-/CO2林格氏液（2.4 mM HCO3-/空气或1 mM HEPES/空气）或高HCO3-/CO2林格氏液（10 mM HCO3-/1% CO2）中。这些研究的主要发现是，在10 mM HCO3-/CO2林格氏液中浸泡的组织，其顶端膜分数电阻（fRa）较高，平均为0.87±0.06，而在2.4 mM HCO3-和1 mM HEPES中，fRa平均分别为0.63±0.07和0.48±0.08。采用上皮内电缆分析来估计浸泡在10 mM HCO3-/1% CO2林格氏液中的组织中单个顶端（Ra）和基底外侧膜（Rb）的电阻。与之前在低HCO3-/CO2林格氏液中浸泡的组织中获得的电阻测量结果相比，发现fRa值较高是由于Ra增加和Rb降低。fRa值较高和Rb值较低证实了其他人最近的观察结果。为了确定造成这些影响的途径，在浆膜溶液K+和Cl-替代过程中测量了细胞膜电压。这些研究结果表明，在浸泡于10 mM HCO3-/1% CO2林格氏液中的组织的基底外侧膜存在电扩散性Cl-转运机制，这可以部分解释Rb的下降。根据溶液[HCO3-]/PCO2对跨上皮液体转运的刺激作用对上述观察结果进行了讨论，该刺激作用导致顶端和基底外侧膜的传导特性发生适应性变化。
