Circadian rhythm of ANP, aldosterone and PRA in normotensive IUGR

Objective Atrial natriuretic peptide (ANP) increases are reported during no rmal pregnancy, but the relation to arterial pressure and the renin-angiote nsin system is debatable. We assessed whether normotensive pregnancies with intrauterine growth retardation (IUGR) present an alteration of maternal A NP levels. Design A total of 11 pregnant women with IUGR, in the absence of any other maternal or fetal pathology, entered the study during the third trimester. They were compared with 12 healthy pregnant women of similar age and charac teristics. We monitored all subjects for blood pressure (BP), ANP, aldoster one and plasma renin activity (PRA), under the same conditions for 24 h. Al l subjects were submitted to the same regimen of life; with homogenous dark : light periods, salt intake and meal times. Methods BP was monitored at 20 min intervals for 24 h and blood tests perfo rmed at six time points during the 24 h. EDTA plasma samples were immediate ly centrifuged. Hormone assays were performed by radioimmunoassay. Koch's nonparametric two-way analysis of variance (ANOVA) was used to compa re the hormone time-dependent profiles in the two groups. Circadian rhythms were assessed by cosinor analysis. Results The IUGR group was characterized by higher ANP values compared to n ormal pregnancy, (205 +/- 24 versus 146 +/- 21 pg/ml: P < 0.05) but not sig nificant differences were shown for PRA, aldosterone and BP circadian rhyth ms. Conclusions This study shows higher ANP values in human pregnancy complicat ed by IUGR, with presence of normal BP, aldosterone and PRA profiles. (C) 2 001 Lippincott Williams & Wilkins.