Plasma concentration of atrial natriuretic polypeptide in patients with atrial tachycardia

To investigate the mechanisms of polyuria associated with tachycardia, we measured plasma concentrations of alpha-human atrial natriuretic polypeptide (alpha-hANP) and cGMP in 6 patients with paroxysmal tachycardia. Plasma concentrations of immunoreactive alpha-hANP and cGMP increased by +69% (p less than 0.05) and +100% (p less than 0.05), respectively, during both paroxysmal atrial tachycardia and atrial fibrillation. To examine whether tachycardia per se raises the secretion of alpha-hANP, we also determined plasma concentrations of alpha-hANP and cGMP in 5 patients during rapid atrial pacing. The pacing-induced tachycardia also increased both of the plasma concentrations. Further, the examinations of cardiac and renal functions in patients with complete atrioventricular block during rapid pacing revealed that each of the increases in atrial pressures, urinary sodium excretion and creatinine clearance were in parallel with the change in plasma concentration of alpha-hANP. These results suggest that an increase in plasma concentration of alpha-hANP during paroxysmal tachycardia is mainly due to elevation of atrial pressure and that this increase in alpha-hANP contributes to tachycardia polyuria.