Late Pregnant Dahl Salt-Sensitive Rats from Charles River Laboratories Do Not Exhibit Superimposed Preeclampsia

Healthy pregnancy is characterized by a reduction in total peripheral vascular resistance which produces a decrease in maternal blood pressure. Failure of this normal maternal adaptation to pregnancy results in hypertensive disorders of pregnancy, which are dangerous for both the mother and fetus. Recently, it has been proposed that Dahl salt-sensitive (SS) rats are a model of spontaneous superimposed preeclampsia when maintained on a normal salt diet. Since these reports are from animals that are derived from sources that are not commercially available, the purpose of this study was to evaluate the blood pressure and pregnancy outcomes of SS rats from a commercial vendor. Mean arterial blood pressure was measured by indwelling femoral catheter in anesthetized SS virgin and SS day 21 late pregnant rats from Charles River Laboratories (CRL). Fetal outcomes from SS rats and control Sprague-Dawley (SD) rats were also measured. All rats were euthanized by exsanguination under anesthesia and tissues weighed. Virgin SS rats were found to have normal mean arterial blood pressure (102 ± 2 mmHg), and late pregnant SS rats had the normal decrease in maternal blood pressure. SS rats were also found to have normal pregnancy outcomes. These results suggest that SS rats from CRL are not a model of superimposed preeclampsia. Further studies will be aimed at determining the differences between the blood pressure phenotype and pregnancy outcomes of existing colonies of SS rats in order to elucidate the mechanisms permitting the development of preeclampsia in certain colonies of this strain.