Differential regulation of natriuretic peptide genes in infarcted rat hearts

1. We investigated the regulation of the atrial natriuretic peptide and brain natriuretic peptide genes in a rat model of myocardial infarction induced by isoproterenol (IP rat) and in a rat model of cardiac hypertrophy induced by aorto-caval shunt (AC shunt rat). 2. Brain natriuretic peptide (BNP) mRNA levels in atria were significantly higher in IP rats than in controls at 18 h after the administration of isoproterenol, but not significant increases were observed in atrial natriuretic peptide (ANP) mRNA expression levels at any time point examined. In the ventricles, the BNP mRNA levels peaked at 18 h after isoproterenol administration, whereas ANP mRNA levels gradually increased until 3 days after isoproterenol administration. 3. The BNP mRNA levels in both atria and ventricles were significantly increased at 1 day after the introduction of aorto-caval shunt, while the ANP mRNA levels were not. 4. Plasma BNP levels were closely correlated with left ventricular weight per bodyweight, in both IP rats and AC shunt rats. 5. These results suggest the differential regulation of ANP and BNP genes in both the atria and ventricles in these two pathological models.