Rich A, Dixon T E, Clausen C
Department of Physiology and Biophysics, State University of New York, Stony Brook 11794-8661.
J Membr Biol. 1990 Feb;113(3):211-9. doi: 10.1007/BF01870073.
Transepithelial impedance-analysis studies were performed in turtle bladder epithelium in order to measure changes in the different epithelial membranes resulting from stimulation of electrogenic bicarbonate secretion. Changes in membrane conductance relate to changes in ionic permeability, whereas changes in membrane capacitance relate to changes in membrane area, since most biological membranes exhibit a specific capacitance of approximately 1 muF/cm2. The results of this investigation are summarized as follows: (i) cAMP and carbachol, agents which have been shown previously to stimulate electrogenic bicarbonate secretion, result in increases in apical-membrane conductance and capacitance; (ii) these changes occur concomitantly with the observed change in transport (measured using the short-circuit-current technique), thereby suggesting that bicarbonate secretion may be regulated in part by changes in the chloride conductance of the apical membrane; (iii) the increase in conductance does not reflect an increase in the membrane's specific conductance, thereby indicating that it results from the addition of membrane possessing similar ionic permeability as the existing apical membrane; (iv) the magnitude of the changes in capacitance indicate that a minor cell population (beta-type carbonic-anhydrase-rich cells) increase their apical-membrane area by several-fold; (v) a lack of transport-associated changes in the basolateral-membrane parameters suggest that transport is not regulated by alterations in basolateral-membrane ionic conductance or area; (vi) a lack of colchicine sensitivity, coupled with the magnitude of the changes in apical-membrane capacitance, indicate that the membrane remodeling processes are different from those involved in the regulation of proton secretion in a different cell population (alpha-type carbonic-anhydrase-rich cells).
为了测量由电生性碳酸氢盐分泌刺激引起的不同上皮细胞膜的变化，对龟膀胱上皮进行了跨上皮阻抗分析研究。膜电导的变化与离子通透性的变化相关，而膜电容的变化与膜面积的变化相关，因为大多数生物膜的比电容约为1μF/cm²。本研究结果总结如下：（i）环磷酸腺苷（cAMP）和卡巴胆碱，这两种先前已被证明能刺激电生性碳酸氢盐分泌的物质，会导致顶端膜电导和电容增加；（ii）这些变化与观察到的转运变化（使用短路电流技术测量）同时发生，从而表明碳酸氢盐分泌可能部分受顶端膜氯离子电导变化的调节；（iii）电导的增加并不反映膜的比电导增加，从而表明它是由具有与现有顶端膜相似离子通透性的膜的添加所致；（iv）电容变化的幅度表明一小部分细胞群体（富含β型碳酸酐酶的细胞）将其顶端膜面积增加了几倍；（v）基底外侧膜参数缺乏与转运相关的变化表明转运不受基底外侧膜离子电导或面积变化的调节；（vi）缺乏秋水仙碱敏感性，再加上顶端膜电容变化的幅度，表明膜重塑过程与另一细胞群体（富含α型碳酸酐酶的细胞）中质子分泌调节所涉及的过程不同。
