Cardiac gene expression and synthesis of atrial natriuretic peptide in thenitrofen model of congenital diaphragmatic hernia in rats: Effect of prenatal dexamethazone treatment

Background/Purpose: The aim of this study was to determine the gene and pro tein levels of atrial natriuretic peptide (ANP) in the heart of nitrofen-in duced congenital diaphragmatic hernia (CDH) in rats and to evaluate the eff ect of antenatal dexamethazone (Dex) treatment. Methods: CDH model was induced in pregnant rats after administration of 100 mg of nitrofen on day 9.5 of gestation (term, day 22). Dexamethazone (Dex, 0.25 mg/kg) was given by intaperitoneal injection on days 18.5 and 19.5 of gestation. Cesarean section was performed on day 21 of gestation. The fetu ses were divided into 3 groups: group I, control (n = 10); group II, nitrof en-induced CDH (n = 10); group III, nitrofen-induced CDH with antenatal Dex treatment (n = 10). ANP protein was measured using enzyme-linked immunosor bent assay (ELISA) technique. Reverse transcription polymerase chain reacti on (RT-PCR) was performed to evaluate the relative amount of atrial natriur etic peptide (ANP) mRNA expression. Results: There was a significant reduction in ANP mRNA (P < .05) and protei n (P < .01) levels in heart of group II (CDH) compared with group I. Antena tal Dex treatment significantly increased both ANP mRNA and protein levels in the heart of CDH animals (P < .05). Conclusions: The reduced cardiac ANP gene expression and ANP synthesis indi cates that the heart in CDH is functionally immature and may be unable to r espond to hemodynamic load accompanying persistent pulmonary hypertension ( PPH). ANP or drugs such as steroids, which raise endogenous ANP levels, may have a therapeutic application in CDH complicated by PPH. Copyright (C) 20 01 by W.B. Saunders Company.