The Osmoregulatory System and the Renin-Angiotensin-Aldosterone System in Pre-Eclampsia and Normotensive Pregnancy

Abstract

Pedersen EB, Johannesen P, Rasmussen AB, Danielsen H. The osmoregulatory system and the renin-angiotensin-aldosterone system in pre-eclampsia and normotensive pregnancy. Scand J Clin Lab Invest 1985; 45: 627–633.

Plasma concentrations of arginine vasopressin (AVP), angiotensin II (A II), aldosterone (Aldo), serum osmolality (S_osm), urine volume (V), and free water clearance (C_H2o) were determined in the third trimester of pregnancy, and 5 days and 3 months after delivery in pre-eclampsia (group I), in normotensive pregnancy (group II), and in non-pregnant control subjects (group III). The AVP was the same in the third trimester of pregnancy in groups I and IT and did not deviate significantly from the level in group III. However, 5 days after delivery, AVP was lower and V and C_H2o higher in group I than in group II. There was no correlation between AVP and S_osm in the third trimester in either group I or II, but 5 days after delivery a significant positive correlation was found between these parameters in both groups I and II as well as in group III. The A II and Aldo changed qualitatively in the same way in groups I and II, that is, considerable elevation in the third trimester and normalization after delivery. Also, A II and Aldo were lower in group I than in II. The AVP and AII were not correlated and there was no significant relationship between systolic or diastolic blood pressure on the one hand and AVP, A II or Aldo on the other in either group I or II. Thus the osmoregulatory system appears to be altered in both pre-eclampsia and normotensive pregnancy, but becomes normal again 5 days after delivery. In pre-eclampsia a suppression of AVP seems to be responsible for the elimination of excess water in pre-eclampsia 5 days after delivery. There was no evidence for a causal relationship between blood pressure and the osmoregulatory system or the renin-angiotensin-aldosterone system in any of the pregnant groups.

Key Words:

• aldosterone
• angiotensin II
• angiotensin II
• hypertension
• kidney function
• pre-eclampsia
• pregnancy
• vasopressin