Plasma and placental calcitonin gene-related peptide in pregnancies complicated by severe preeclampsia

OBJECTIVE: Our purpose was to determine the concentration of calcitonin gene-related peptide, a potent vasodilator, in maternal plasma, fetal plasma, and placental tissue from pregnancies complicated by severe preeclampsia. STUDY DESIGN: The following groups were studied: severe preelcmapsia (group 1, n = 21), normal pregnancies matched for mode of delivery (group 2, n = 21), and nonpregnant women (group 3, n = 17). Maternal venous blood samples were drawn before labor, and fetal venous samples were drawn from the chorionic plate immediately after delivery. Calcitonin gene-relted peptide was also quantified in placental tissue samples from 15 patients in group 1 and 15 patients in group 2. Calcitonin gene-related peptide was measured with a sensitive and specific radioimmunoassay. RESULTS: No differences were found between maternal plasma calcitonin gene-related peptide concentrations in groups 1 and 2 (29.8 ± 4.2 and 30.4 ± 4.3 pmol/L, respectively). Both had levels similar to those in group 3 (28.5 ± 5.4 pmol/L). Maternal plasma concentrations in the preeclamptic group were unchanged 3 days post partum (29.1 ± 3.6 pmol/L). Fetal plasma calcitonin gene-related peptide concentrations were similar in groups 1 and 2 (30.2 ± 3.9 and 32.2 ± 8.8 pmol/L, respectively). A significant correlation was found between maternal and fetal calcitonin gene-related peptide concentrations (r = 0.43, p< 0.01). Like plasma levels, calcitonin gene-related peptide levels in the supernatants of placental extracts were not different in preeclamptic and normal pregnancies (108.0 ± 70.4 and 100.9 ± 56.1 fmol/gm, respectively). CONCLUSION: On the basis of plasma and placental concentrations, calcitonin gene-related peptide does not seem to play an important role in the pathophysiologic mechanisms of preeclampsia.