Maternal effects on blood pressure and survivability in inbred Dahl salt-sensitive rats.

Maternal effects on blood pressure response to high salt diet were evaluated using inbred Dahl salt-sensitive (S/JR) and inbred Dahl salt-resistant (R/JR) rats. A cross-fostering experiment did not yield any evidence for a consistent effect of strain-specific fostering environments on the subsequent blood pressure response of S/JR or R/JR rats. A small increment in blood pressure seen only in male rats associated with the maternal R/JR environment was probably the result of effects mediated through an increment in body weight. In an experiment in which litter size was varied, weaning body weight was found to be an important predictor of survivability of S/JR rats fed a high salt (8% NaCl) diet; higher body weight was associated with longer survival in both males and females. Higher body weight at weaning also was associated with a small increment in blood pressure of S/JR rats in male, but not in female, rats. Intrauterine environment was evaluated using the embryo transplant technique. No evidence for a difference between S/JR and R/JR intrauterine environments with regard to blood pressure response of S/JR pups to salt was found. It is concluded that the early nutritional level during nursing as altered by varying litter size has important effects on body weight and survivability of S/JR rats on high salt diet, but that these effects are not mediated through changes in blood pressure. We found no evidence for genetic effects on blood pressure operating through the early maternal intrauterine or fostering environments.