Abnormal respiratory system physiology Hyperpolarized transepithelial nasal potential difference 2023-12-31T10:32:04Z Increased (more negative) voltage across the nasal epithelium. The resulting (or basal) potential difference (PD) is negative or polarized (viewed from the epithelial surface) and in normal subjects, it is usually between -15 and -25 mV. The measurement continues by the sequential perfusion of compounds that block inwardly directed sodium transport through inhibition of ENaC (amiloride), followed by augmentation of chloride transport through CFTR. During perfusion of amiloride, the potential difference depolarizes as ENaC transport is reduced, and the PD typically approaches a low polarizing value (typically between 0 and -10 mV).