ELSEVIER Regulatory Peptides 66 (1996) 113-115 REGULATORY PEPTIDES Changes of blood pressure responsiveness in rats exposed in utero and perinatally to a high-salt environment J. ArgiJelles *, P. L6pez-Sela, J.I. Brime, M. Costales, M. Vijande Dpto. Biologfa Funcional, Area de Fisiologia, UniL'ersidad de Oviedo, Oviedo, Spain Received 15 December 1995; revised 15 March 1996: accepted 20 March 1996 Abstract We tested the hypothesis that the pressor responses to angiotensin II could be influenced by an early salt exposure. Twenty-five adult female rats were pseudorandomly divided in two groups. Twelve animals underwent a partial ligature of their abdominal aorta (PAL). Once polydipsia and sodium appetite developed, these rats were mated. The other group (13 rats) was sham-operated (Sham) and mated. Throughout pregnancy and lactation, water and 2.7% NaCI solution intakes differed between the two groups of mother rats. PAL offspring (PAL-O; n = 14), and Sham-operated offspring (Sh-O; n = 10), were maintained on a solid diet containing 1% NaC1, tap water and a 2.7% NaC1 solution. At 90 days of age, pressor responsiveness to intravenous angiotensin II (50, 100 and 200 ng) was assessed in anesthetized rats. The pressor responses to 50 and 200 ng angiotensin II were significantly greater in PAL-O rats than in Sh-O rats. These results support the hypothesis of a modulation of cardiovascular responsiveness or its underlying mechanisms by an early high salt environment. Keywords: Blood pressure; Heart rate; Angiotensin II; Salt intake; Pregnancy Consuming a diet high in salt is a well-known hyperten- siogenic element in many animals. Most of the current literature has focused on the effects of salt overload or restriction on adult animals. Very few studies have dealt with the effects imposed by changes in the intrauterine and perinatai environment. Nevertheless, some experimental results give evidence of the importance of changes in the salt environment during an 'early critical period' (in utero and preweaning) on hydromineral homeostasis and blood pressure regulation of the adult individuals. Nicolaidis et al. [1] induced extracellular dehydration in pregnant rats by a subcutaneous injection of polyethylene glycol, demonstrating that the offspring of these dams increased their salt appetite. Another experimental ap- proach was made by Contreras [2] who gave female Sprague-Dawley rats diets containing either 0.12, 1 or 3% NaC1 during gestation and also to the offspring until 30 days of age. He observed an elevation of systolic pressure in the young rats, significantly higher in animals raised on 3% NaC1 diet with respect to those raised on 0.12 or 1% NaC1 diets. * Corresponding author. Our study describes the influence on the blood pressure responsiveness to angiotensin II of the adult offspring of dams subjected to partial ligature of the abdominal aorta (PAL), which promotes the development of salt appetite, polydipsia and hypertension. Twenty-five nulliparous rats (Wistar, obtained from the vivarium of the Faculty of Medicine of Oviedo, Spain), weighing 250-275 g were housed in individual breeding cages in a colony room on a 12:12 h light-dark cycle, in which the temperature varied between 20 and 22°C. Each rat was given ad libitum access to standard laboratory diet (containing 1% NaC1), tap water and 2.7% NaC1, available from graduated glass cylinders fitted with glass spouts. After 5 days of adaptation to these conditions, under equithesin anaesthesia (0.4 ml/100 g b.wt.), animals were subjected to either partial aortic ligature (PAL) or a sham operation (Sham). The abdominal aorta was approached through an abdominal incision; once the aorta between the renal arteries was cleared, it was partly occluded by tying a silk thread (no. 4/0) around it just below the mesenteric artery and above the left renal artery with a stylus (O.D. 0.5 mm) included within the ligature, and then removing the stylus. The abdominal incision was closed at layers [3]. All animals were allowed a 5-day recovery period. Then both PAL rats (n = 12) and Sham rats (n = 13) were 0167-0115/96/$15.00 Copyright © 1996 Elsevier Science B.V. All rights reserved. Pll S01 67-0115(96)00051-1