DIFFERENTIAL REGULATION OF NATRIURETIC PEPTIDE GENES IN INFARCTED RATHEARTS

1. We investigated the regulation of the atrial natriuretic peptide an d brain natriuretic peptide genes in a rat model of myocardial infarct ion induced by isoproterenol (IP rat) and in a rat model of cardiac hy pertrophy induced by aorto-caval shunt (AC shunt rat). 2. Brain natriu retic peptide (BNP) mRNA levels in atria were significantly higher in IP rats than in controls at 18 h after the administration of isoproter enol, but no significant increases were observed in atrial natriuretic peptide (ANP) mRNA expression levels at any time point examined, In t he ventricles, the BNP mRNA levels peaked at 18 h after isoproterenol administration, whereas ANP mRNA levels gradually increased until 3 da ys after isoproterenol administration. 3. The BNP mRNA levels in both atria and ventricles were significantly increased at 1 day after the i ntroduction of aortocaval shunt, while the ANP mRNA levels were not. 4 . Plasma BNP levels were closely correlated with left ventricular weig ht 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.