OBJECTIVETo examine serum B-type natriuretic peptide (BNP) levels and BNP expression of protein and mRNA in the right ventricular myocardium in juvenile rats with right heart failure (RHF) and the effects of beta-adrenergic receptor blocker carvedilol on serum and myocardial BNP levels in order to investigate the role of BNP in the diagnosis and treatment of RHF.

METHODSFifty-one four-week-old Sprague-Dawley rats were randomly assigned to 5 groups: RHF 1, RHF 2, carvedilol-treated RHF, control 1 and control 2. RHF was developed 4 weeks after an intraperitoneal injection of monocrotaline in the RHF 1, RHF 2 and carvedilol-treated RHF groups. The rats in the RHF 1 and the control 1 groups were sacrificed after the RHF event for observing pathological changes in the myocardium. After the RHF event, the carvedilol-treated group was given intragastric administration of carvedilol (3.5 mg/kg/d) for 2 weeks. The RHF 2 and the control 2 groups were given distilled water of equal dose instead. The rats were sacrificed 2 weeks after carvedilol or distilled water administration. Serum BNP levels were measured using ELISA. BNP protein and mRNA expression in the right ventricular myocardium were measured by immunohistochemistry and RT-PCR, respectively. Haemodynamics and some physiological indexes were measured.

RESULTSSerum BNP levels and BNP protein and mRNA expression in the right ventricular myocardium were significantly higher in the RHF 1 group than those in the control 1 group (p<0.01). Serum BNP levels and BNP protein and mRNA expression in the right ventricular myocardium increased more significantly in the RHF 2 group. There was a positive correlation between serum BNP levels and myocardial BNP protein expression in the RHF group (r=0.698, p<0.01). Serum BNP levels and BNP protein and mRNA expression in the carvedilol-treated RHF group were significantly reduced when compared with the RHF 2 group (p<0.05). Carvedilol treatment also resulted in improved hemodynamics and relieved right ventricular hypertrophy.

CONCLUSIONSBNP may serve an index for the diagnosis of RHF and the evaluation of severity in children with RHF. Carvedilol shows protections against RHF caused by pressure load.