EFFECTS OF ATRIAL-NATRIURETIC-FACTOR INFUSION ON PLASMA PRORENIN LEVELS IN HYPERTENSIVE MALES

To evaluate the influence of atrial natriuretic factor (ANF) infusion on circulating prorenin, 20 essential hypertensive males, aged between 40 and 60 years, were studied. After 2 weeks under normal sodium inta ke (120 mmol NaCl per day), patients were randomly assigned to receive either ANF (0.01 fmol/Kg/min) (n.12 patients) or its vehicle (50 mL o f isotonic saline). (n.8 patients) over a period of 60 minutes. Blood samples for plasma renin activity (PRA), prorenin and aldosterone (PAC ) were taken at time -60, 0, 20, 40, 60, 120, 180, 240 minutes (infusi on time: from 0 to 60 minutes). PRA and PAC decreased during the ANF i nfusion (PRA: from 0.33+/-0.05 ng/L/s at time 0 to 0.10+/-0.06 ng/L/s at 60 minutes, p<0.0001; PAC: from 389.2+/-99.8 pmol/L at time 0 to 14 8.7+/-44.3 pmol/L at 60 minutes, p<0.0001), while returned immediately to baseline levels after the infusion was stopped (PRA: 0.37+/-0.11 n g/L/s at 180 minutes, PAC: 251.6+/-72.1 pmol/L at time 180 minutes). O n the contrary, plasma prorenin increased during ANF infusion (from 1. 66+/-0.58 ng/L/s at time 0 to 2.44+/-0.72 ng/L/s at 60 minutes, p<0.05 ), and returned to baseline levels after the end of the infusion (1.86 +/-0.83 ng/L/s at 180 minutes). These data indicate that ANF infusion may alter only the circulating levels of active renin, without affecti ng plasma prorenin secretion.