Abstract

OBJECTIVE--To document regional plasma concentrations of brain natriuretic factor (BNF) and their relations to concurrent concentrations of atrial natriuretic factor, cyclic guanosine monophosphate, and haemodynamic state. DESIGN--Regional blood sampling from a systemic artery and vein, renal vein, and coronary sinus together with concurrent haemodynamic indices in patients coming forward for left and right cardiac catheterisation. SETTING--Tertiary referral centre. PATIENTS--22 consecutive unselected patients coming forward for left and right cardiac catheterisation or electrophysiological studies in the course of standard diagnosis for a range of cardiac disorders. MAIN OUTCOME MEASURES--Significant arteriovenous gradients for plasma BNF concentration were found across the lower limb, the kidney, and the heart. These were less than concurrent arteriovenous gradients in plasma atrial natriuretic factor (ANF). Arterial concentrations of plasma BNF were positively related to concurrent concentrations of ANF (r = 0.72, p < 0.01) and cyclic guanosine monophosphate (r = 0.52, p < 0.05). Arterial plasma concentrations of BNF showed a significant positive correlation with right atrial pressure and pulmonary artery wedge pressure and an inverse relation to cardiac output. CONCLUSIONS--Regional plasma concentrations of BNF indicate cardiac secretion of this peptide and clearance in a number of tissues. Renal clearance is proportionally greater than that found across the limb. Absolute and proportional arteriovenous gradients of this peptide are considerably less than for concomitant concentrations of ANF suggesting slower metabolic clearance of BNF. Plasma BNF concentrations rise with increasing cardiac impairment and are related to indices of cardiac function. These findings are consistent with a role for BNF in the neurohumoral response to cardiac impairment.