Effect of nitric oxide on the development of nitrofen-induced fetal hypoplastic lung explants

Abstract

Background/Purpose Nitric oxide (NO) is an important cell-signaling molecule, and its generators, nitric oxide synthases, are expressed temporospatially in fetal rat lung. Recently, NO has been reported to modulate branching of the fetal rat lung lobe in vitro. We designed this study to evaluate the effect of NO on the morphogenesis of hypoplastic lung using nitrofen-induced rat lung explant model. Methods A hypoplastic fetal lung model and a normal control lung model were induced by feeding a pregnant rat with nitrofen (100 mg) or olive oil on day 9.5 of gestation, respectively. Fetal lungs were harvested on day 13.5 and placed in organ culture containing serum-free medium Dulbecco modified Eagle medium. An NO donor, DETA NONOate (DETA/NO), was added daily in the culture medium. The lung cultures were divided into 4 groups: group 1 (n = 8), normal controls without DETA/NO; group 2 (n = 22), normal controls with DETA/NO; group 3 (n = 13), hypoplastic lungs without DETA/NO; group 4 (n = 22), hypoplastic lungs with DETA/NO. The fetal lungs were incubated for 48 hours at 37°C with 5% CO 2. Lung bud count and area of the specimens were measured under computer-assisted digital tracings. The rate of increase in bud count and lung area was calculated as the ratio of each value at 48 hours minus each value at 0 hour, divided by the value at 0 hour. Results The lung bud count was significantly increased in group 2 compared with group 1 at a concentration of 50 μmol/L DETA/NO ( P < .05). In the nitrofen group, the lung bud count was significantly increased in group 4 compared with group 3 at 100 μmol/L DETA/NO added ( P < .05). There was no significant difference in the rate of increase in whole lung area among the 4 groups. The peak increase rates of lung area and bud count were significantly lower in group 4 compared with group 2. Conclusions This study demonstrates that the NO donor, DETA/NO, promotes branching of the nitrofen-induced hypoplastic fetal lung explant. These data suggest that NO may modulate the development of the nitrofen-induced hypoplastic lung.