Current-voltage relationship of the basolateral membrane of a tight epithelium.

The polyene antibiotic nystatin is used to reduce selectively to zero the apical membrane resistance of the rabbit descending colon, allowing the measurement of the current-voltage curve of the basolateral membrane. The I--V relationship is described by the Goldman-Hodgkin-Katz equations allowing calculation of PNa/PK, PCl/PK and PK for the basolateral membrane. Cs+ is found to block inward current (serosa to mucosa) in a manner similar to that found in excitable membranes.