Electrical potential difference and ion transport across nasal epithelium of term neonates: Correlation with mode of delivery, transient tachypnea of the newborn, and respiratory rate C, W. Gowen, Jr,, MD, Edward E, Lawson, MD, Jeannine Gingras, MD, Richard C. Boucher, MD, John T, Gatzy, PhD, and Michael R, Knowles, MD From the Department of Pediatrics, East Carolina University School of Medicine, Greenville, North Carolina, and the Departments of Pediatrics, Medicine, and Pharmacology, University of North Carolina at Chapel Hilt We studied the change In ion transport function by measuring the basal transeplthelial potential difference (PD) across the clliated epithelium of the nose in 85 term neonates during the first 72 hours of life. Differences in PD associated with the mode of delivery or the presence of respiratory disease and differences in the PD response to the superfusion of amllorlde (10 -5 mol/L) were assessed. We also studied term neonates with transient tachypnea of the newborn (TTN) and acute respiratory insufficiency. Basal PDs during the first 24 hours of llfe were higher in neonates delivered by cesarean section without prior labor (-29.7 _ 2.5 mY) and in those with TTN (-38.5 _ 6.0 mY) than in neonates born during normal spontaneous vaginal dellvery (-23.0 ___ 2.9 mY) or cesarean section with prlor labor (-23.7 +__ 0.7 mV) or in those wlth respira- tory Insufficiency (-22.4 _+ 2.3 mV). The percentage inhibition of PD by amllo- ride superfusion (<24 hours) was significantly lower in infants with TTN (30.9 _ 4.9%) and after cesarean section without prior labor (31.8 _+ 2.2%) than in other groups (37.6 _ 1.6%). By 48 hours, nasal PDs after cesarean section without prior labor and in neonates with TTN had declined; and by 72 hours, values were similar to those in other groups; respiratory rate paralleled the decline in PD. The respiratory rate of neonates with respiratory insufficiency remained hlgh and paralleled the persistence of respiratory distress. Amiloride sensitivity was similar for all groups by 72 hours. These findings indicate (I) that PDs vary with the mode of delivery and support a role for labor in the normal transition of respiratory epithelial ion transport and (2) that TTN is associated with abnormal epithelial ion transport. (J PEDIATR 1988;113:121-7) Supported by grants No. NDO 475 and No. NHLBI-HL34322- 03 from the National Institutes of Health, and by a research grant from the American Lung Association of North Carolina. Presented in part at the annual meeting of the Society for Pediatric Research, April 1987. Submitted for publication Oct. 5, 1987; accepted Jan. 21, 1988. Reprint requests: C. W. Gowen, Jr., MD, Department of Pediat- rics, East Carolina University School of Medicine, Greenville, NC 27858-4354. The measurement of nasal epithelial potential difference has served as a relatively noninvasive index of airway CS g labor CS ~ labor NSVD PD TTN Cesarean section with (prior) labor Cesarean seation without (prior) labor Normal spontaneous vaginal delivery Potential difference Transient tachypnea of the newborn 121