Atrial Natriuretic Factor in Pregnancy-induced Hypertension and Preeclampsia: Increased Plasma Concentrations Possibly Explaining These Hypovolemic States With Paradoxical Hyporeninism

Abstract

Plasma immunoreactive atrial natriuretic factor 99-126 (ir ANF), plasma volume, plasma renin activity, and plasma aldosterone were measured during pregnancy in 14 normotensive nonpregnant women, 15 normotensive pregnant women, 35 patients with pregnancy-induced hypertension (PIH), and in ten patients with preeclampsia (PE). Repeated measurements were carried out 2 months after delivery in a subgroup of the same patients. The plasma levels of ANF were found to be higher in pregnant normotensive women than in nonpregnant normotensive women, but the decrease of plasma ANF 2 months after delivery was not significant on the basis of seven paired data, so that it cannot presently be stated with certainty that pregnancy per se stimulates ANF secretion. Still higher levels of ANF were found in PIH and, especially, in PE. A positive correlation was found in the pooled population of normotensive and hypertensive pregnant women between plasma ANF and mean arterial pressure. A greater decrease of plasma ANF was found after delivery in the hypertensive patients than in the normotensive controls. This excludes an absolute deficiency of ANF secretion in the pathogenesis of hypertension. These findings suggest a compensatory role of ANF in the prevention of blood pressure increase. Plasma renin activity (PRA) and plasma aldosterone concentrations were higher in normotensive pregnant women than in normotensive nonpregnant women. Compared to normal pregnancy, plasma volume was decreased in PIH (-17%) and in PE (-25%), whereas PRA was less increased in both groups and plasma aldosterone concentration was less increased only in the PE group. The simultaneous high levels of plasma ANF may explain this inappropriate hypostimulation of renin secretion by hypovolemia in these hypertensive states.

Cyclic guanosine 3′3′ monophosphate concentrations in pre‐eclampsia: effects of hydralazine

“…However, there was a tendency for ANF to be higher in the pregnant women, particularly in the pre‐eclampsia group. Most investigators have found that ANF is increased in normal pregnancy and paradoxically increased further in pre‐eclampsia 16,18 . Thus, it is likely that the increases we have observed in urinary and plasma cyclic GMP concentrations in normal pregnancy can be due, at least partially, to an influence of ANF.…”

The Physiology of Pre‐eclampsia

“…Pre-eclampsia is associated with plasma volume reduction, yet most studies have found that plasma ANP is actually increased in pre-eclampsia (Fievet et al 1988;Malee et al 1992). Lowe er al.…”

“…ANP is predominantly produced by the atria in response to atrial stretch and other factors, but is also produced at other sites, including the placenta. Pre-eclampsia is associated with plasma volume reduction, yet most studies have found that plasma ANP is actually increased in pre-eclampsia (Fievet et al 1988;Malee et al 1992). Lowe er al.…”

Atriales Natriuretisches Peptid (ANP) und Renin-Angiotesin-Aldosteron-System (RAAS) bei schwangerschaftsinduzierter Hypertonie (SIH)

“…Da es bei Sill erh6ht ist, scheint ihm eher eine kompensatorische Rolle zur Verhtimng eines zu starken Blutdruckanstiegs zuzukommen. Je h6her der Blutdruck ist, desto mehr ANP wird Zusammenfassend ergibt sich, dab das ANP sicherlich eine wichtige Rolle in der Regulierung yon Blutdruck und -volumen sowohl in der hypertonen Schwangerschaft spielt, was durch mehrere andere Arbeiten best~ifigt werden konnte (2,3). Ob das ANP als prognostischer oder diagnosfischer Faktor benutzt werden kann oder ob sogar therapeutische Anwendungsm6glichkeiten bestehen, mug sich in der Zukunft zeigen.…”