The atrial natriuretic factor in hypertension.

Plasma immunoreactive atrial natriuretic factor (IR-ANF) concentration measured by radioimmunoassay after extraction on Sep-Pak cartridges was studied in 64 control normotensive subjects, 25 patients with labile essential hypertension, 67 patients with mild essential hypertension (diastolic pressure between 90 and 105 mm Hg and no left ventricular hypertrophy) and 9 patients with moderate to severe essential hypertension (diastolic pressures between 105 and 120 mm Hg). An additional group of 16 patients under medication but without effective control of their blood pressure and with diastolic pressure above 110 mm Hg also was studied. Results show that plasma IR-ANF concentrations are within normal range in patients with labile, mild, and moderate hypertension. In view of the reported increased right and left atrial pressures and distension in patients with mild and moderate hypertension, these findings strongly suggest a state of hyporesponsiveness of the atria to release ANF.