Ontogeny of blood pressure in the inbred Dahl hypertension-sensitive and -resistant rat.

The inbred S/JR rat is characterized by a genetic predisposition to NaCl-induced hypertension. Although mature S/JR but not R/JR rats develop hypertension when fed a high NaCl-containing diet, this effect has not been examined during early neonatal development. S/JR and R/JR dams were maintained on 0.15% (w/w) or 8% (w/w) NaCl diets throughout gestation and lactation. Measurements of mean abdominal aortic blood pressure (MAP) were obtained in anesthetized offspring at 5, 15, and 25 days of age. This was greater in neonatal S/JR rats than R/JR rats at 5, 15, and 25 days of age. A hypertensinogenic effect of 8% NaCl was seen in R/JR at 5 and 15 days. The results indicate that the ontogeny of MAP can be influenced by pre- and postnatal dietary NaCl. More importantly, elevated MAP in the S/JR strain is a distinguishing characteristic evident throughout the neonatal period of development.