ELEVATION OF BLOOD-PRESSURE DURING PREGNANCY IN UNINEPHRECTOMIZED ANDSALT-LOADED WISTAR RATS

Objective: The influence of uninephrectomy and salt loading on blood p ressure (BP) during pregnancy was examined in pregnant Wistar rats. Me thods: BP was measured by the indirect tail-cuff method every day duri ng pregnancy in the following five groups: group 1 (n = 18, uninephrec tomy on the first day of gestation + 8% high-salt diet), group 2 (n = 8, uninephrectomy + 0.4% low-salt diet), group 3 (n = 14, sham operati on + high-salt diet), group 4 (n = 8, sham operation + low-salt diet), and group 5 (n = 8, nonpregnant female rats, uninephrectomy + high-sa lt diet). Results: Systolic BP in Group I increased significantly from midpregnancy and exceeded 140 mm Hg in late pregnancy. On day 17 of g estation, systolic BP in Group 1 (140.5 +/- 4.3 mm Hg) was significant ly higher than in the other four groups (114.8 +/- 3.8, 123.1 +/- 3.6, 117.9 +/- 3.8, 123.0 +/- 3.5 mm Hg, P < 0.05, respectively). Systolic BP was increased in uninephrectomized and salt-loaded pregnant rats b ut not in rats with two kidneys, uninephrectomized rats on a low-salt diet, or uninephrectomized and salt-loaded nonpregnant rats on a high- salt diet. Conclusions: Reduced renal mass and salt loading may predis pose to the development of hypertension during pregnancy.