Synthetic Atrial Natriuretic Factor Induces Release (Possibly Receptor-Mediated) of Vasopressin from Rat Posterior Pituitary

The synthetic fragment (Arg 101-Tyr 126) of atrial natriuretic factor (ANF) induces release of arginine vasopressin from the isolated posterior lobe of the rat hypophysis in vitro. At a physiological concentration (3 X 10(-10)M) ANF was three times more effective than 61 mM KCL. In vitro binding studies with 125I-ANF revealed the presence of high affinity receptor sites displaying a pK = 9.9, a Kd = 0.14 nM, a Bmax = 20 fmol/posterior lobe and and IC50 = 200 pM. These results suggest that arginine vasopressin release by synthetic atrial natriuretic factor may be receptor mediated.