Impaired renin stimulation in pre-eclampsia.

1. Pre-eclampsia is characterized by reduced plasma active renin concentration and renal prostacyclin production. The aim of this study was to determine whether the plasma active renin concentration could be stimulated in women with pre-eclampsia by intravenous frusemide, which stimulates renin acutely through a prostacyclin-mediated mechanism. 2. Plasma active renin concentration, plasma aldosterone concentration, haematocrit and urinary sodium, creatinine and 6-keto-prostaglandin F1 alpha were measured before (0) and 15, 30 and 60 min after intravenous frusemide in 10 non-pregnant women, 10 normal pregnant women and nine women with pre-eclampsia. Six normal pregnant and six non-pregnant women underwent the same measurements after injection of 2ml of saline to control for effects of time and posture. 3. Baseline plasma active renin concentration (but not plasma aldosterone concentration) was lower in pre-eclamptic women [4.0 (1.7-6.2) pmol of angiotensin I h-1 ml-1; median (interquartile range)] than in normal pregnant women [6.7 (5.3-12.2) pmol of angiotensin I h-1 ml-1] (P < 0.05). Baseline urinary 6-keto-prostaglandin F1 alpha/creatinine ratio, urinary sodium excretion and fractional sodium excretion did not differ between normal pregnant and pre-eclamptic women. 4. After frusemide, plasma active renin concentration rose significantly in non-pregnant (P = 0.002) and normal pregnant (P = 0.008) women, but not in women with pre-eclampsia. Individual results showed stimulation in all non-pregnant and normal pregnant women but in only six out of nine pre-eclamptic women, significantly fewer than in normal pregnancy (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)