Wills N K
Fed Proc. 1981 Jun;40(8):2202-5.
Antibiotics were used as tools for probing the electrical properties of tight epithelia (i.e., epithelia with high electrical resistance). The electrical effects of the polyene antibiotic nystatin were assessed in two mammalian epithelia: the rabbit descending colon and the rabbit urinary bladder. In both tissues, luminal application of the drug increased transepithelial potential and conductance and virtually eliminated apical membrane resistance by increasing permeabilities to Na+, K+, and Cl-. Application of another antibiotic, gramicidin D, produced similar effects on the urinary bladder except that Cl- permeability was unaltered. These effects permitted estimation of apical membrane basolateral membrane, and tight junctional conductances. In addition, a method was developed for assessing active and passive properties of the basolateral membrane. In both the bladder and the colon the membrane behaved basically as a potassium electrode with finite permeabilities for Na+ and Cl-, although an electrogenic Na+ pump was also identified. The existence of this pump was independently verified using ion-sensitive microelectrodes. Recent experiments are consistent with a 3 Na:2 coupling ratio for the pump.
抗生素被用作探测紧密上皮组织（即具有高电阻的上皮组织）电学特性的工具。在两种哺乳动物上皮组织中评估了多烯抗生素制霉菌素的电学效应：兔降结肠和兔膀胱。在这两种组织中，药物腔内应用增加了跨上皮电位和电导，并通过增加对Na⁺、K⁺和Cl⁻的通透性几乎消除了顶端膜电阻。另一种抗生素短杆菌肽D的应用对膀胱产生了类似的效应，只是Cl⁻通透性未改变。这些效应使得能够估计顶端膜、基底外侧膜和紧密连接的电导。此外，还开发了一种评估基底外侧膜主动和被动特性的方法。在膀胱和结肠中，该膜基本上表现为一个对Na⁺和Cl⁻具有有限通透性的钾电极，尽管也鉴定出了一个电生Na⁺泵。使用离子敏感微电极独立验证了该泵的存在。最近的实验与该泵的3个Na:2个耦合比一致。
