Adenosine stimulates ANP expression in cultured ventricular cardiomyocytes

Adenosine protects the ischemic myocardium by coronary vasodilation and the depression of heart rate and contractility, improving myocardial energy balance. Adenosine effects on the myocardium are mediated predominantly by the type A1 receptors. Atrial natriuretic peptide (ANP), a vasodilator and regulator of blood volume, is secreted from either atrial or ventricular myocytes in response to cellular distention. In vivo, adenosine infusion has been shown to induce a rapid increase in plasma ANP, independent of blood pressure. We examined the possibility that adenosine enhances ANP-gene expression in cardiac myocytes. Administration of adenosine (10 microM) to cultured neonatal rat cardiomyocytes led to a 1.7-fold increase (p = 0.014, n = 9) in the abundance of ANP messenger RNA (mRNA) within 30 min, as measured by Northern blot hybridization. No such increase was obtained when adenosine was coadministered with 8-cyclopentyl-1,3dipropylxanthine (CPX, 10 microM), an adenosine A1-receptor antagonist. Our results point at adenosine as regulator of ANP mRNA level in cardiac myocytes.