Atrial antinatriuretic factor in the developing Dahl hypertensive rat.

In order to determine the developmental pattern of atrial concentrations of atrial natriuretic factor (ANF) in the Dahl hypertension-prone rat, atrial ANF concentrations were measured in inbred hypertension-prone (S/JR) and hypertension-resistant (R/JR) Dahl rats at 5, 15, 25, and 51 days of age. In both strains, atrial ANF concentrations peaked at 15 days of age. Atrial ANF concentrations did not differ between the two strains from 5 to 25 days of age. However, by 51 days of age, atrial ANF concentrations in the S/JR rat were significantly greater than those of the R/JR rat. Combining these data with developmental patterns of plasma renin activity in S/JR rats suggests the possibility that the S/JR rat may become intravascularly volume-expanded between 25 and 51 days of age. This volume expansion may contribute to the etiology of hypertension in this model of essential hypertension.