Intrauterine growth restriction in spontaneously hypertensive rats

We examined the test profile of changes in systolic blood pressure (SBP), urinary volume, urinary sodium, and protein excretion in normotensive (Sprague Dawley) and spontaneously hypertensive rats (SHR) up to the 18th day of pregnancy. On days 6, 11, and 18 of pregnancy, the number of implantation sites, number of embryos, litter size, placenta, and litter weight were determined. In SHR, SBP (mmHg) increased significantly from the start of the test and remained high throughout the experiment. There was also a significant increase in urine volume (mL per 24 hrs) and urinary sodium excretion (mEq per 24 hrs) but no significant changes in protein excretion rate. The number of implantation sites on day 6 of pregnancy and the number of embryos on day 11 were similar in both groups. Uterus weight in SHR on days 6 and 11 of pregnancy was significantly lower than in normotensive rats. On day 18 of pregnancy in SHR, a substantial decrease in litter weight (7.10 +/- 0.40 vs. 12.00 +/- 0.92 g; p < 0.001) and weight of placenta (2.35 +/- 0.07 vs. 4.74 +/- 0.21 g; p < 0.001) was observed, with no modification in litter size. The hypertension associated with pregnancy in SHR increased urine volume and urinary sodium excretion and decreased weight of uterus, litter, and placenta relative to control rats.