Objective: Our purpose was to quantify fetoplacental vascular atrial natriuretic peptide receptor subtypes in human pregnancies complicated by intrauterine growth retardation or preeclampsia and to relate these parameters to the fetoplacental vascular impedance as assessed by Doppler velocimetry.
Study design: Guanylate cyclase-coupled and uncoupled receptors were quantified by radioligand-binding methods in membrane fractions prepared from primary and secondary stem villous vessels. Data for 16 abnormal pregnancies delivered preterm were compared with that for six gestationally matched preterm controls.
Results: The number of guanylate cyclase-coupled receptors was significantly (p < 0.001) greater in pregnancies complicated by intrauterine growth retardation or preeclampsia irrespective of normal or abnormal umbilical artery Doppler blood flow velocity pattern. The number of guanylate cyclase-uncoupled receptors was unaltered.
Conclusions: Because fetal plasma atrial natriuretic peptide concentration is normal or elevated in intrauterine growth retardation and preeclampsia, these data suggest that atrial natriuretic peptide-mediated fetoplacental vasodilation is augmented in these disorders even in the presence of increased vascular resistance within the fetoplacental unit.