PLASMA PROHORMONE ATRIAL NATRIURETIC PEPTIDES 1-98 AND 31-67 INCREASE WITH SUPRAVENTRICULAR AND VENTRICULAR ARRHYTHMIAS

Recently two peptides consisting of amino acids (AA) 1-30 and 31-67 of the N-terminus of the 126 AA prohormone of atrial natriuretic factor (pro ANF) as well as atrial natriuretic factor (ANF, AA 99-126; C-terminus) were found to have vasodilatory and natriuretic properties. These peptides as well as ANF circulate in man as part of the N-terminus of the prohormone. To determine if the polyuria, associated with both ventricular and supraventricular arrhythmias, is associated with increased circulating concentrations of the N-terminus and C-terminus of the ANF prohormone, 20 individuals with spontaneous arrhythmias, including ten persons with atrial fibrillation, six with paroxysmol supraventricular tachycardia, and four with ventricular tachycardia, were evaluated before and after conversion to sinus rhythm. In all 20 patients, the circulating concentrations of the whole N-terminus (ie, AA 1-98), the midportion of the N-terminus (pro ANF 31-67) that circulates as a distinct 3,900 molecular weight peptide after being proteolytically cleaved from the N-terminus, and the C-terminus were significantly higher (p < 0.001) than their concentration in 54 persons with sinus rhythm. With conversion to sinus rhythm, the plasma C-terminus concentration of these 20 arrhythmia patients decreased the level of persons with sinus rhythm within 30 minutes. However, the whole N-terminus and pro ANF 31-67, although beginning to decrease immediately with conversion, did not decrease to the levels of persons with sinus rhythm even after 180 minutes post-cardioversion. The sustained elevation of the N-terminus containing natriuretic and diuretic peptides after cardioversion may help explain the diuresis that continues long after atrial natiuretic factor has returned to normal.