Dissociation of adrenomedullin concentrations in plasma and cerebrospinal fluid in pregnant and non-pregnant women

Adrenomedullin (AM), a potent vasodilator peptide, has been shown to act wi thin the central nervous system to modulate fluid and electrolyte balance. AM-immunoreactive cells have been found in the anterior pituitary gland and the choroid plexus of humans. In addition, AM activity has been implicated in the regulation of maternal circulation during pregnancy. To determine t he relationship between AM concentration in the cerebrospinal fluid (CSF) a nd plasma, we measured AM levels in CSF and plasma of pregnant (group P, n = 12) and non-pregnant (group NP, n = 10) women scheduled to undergo gyneco logic or obstetric surgery. In both groups, the concentration of AM in the plasma exceeded that in the CSF Plasma AM concentration was significantly h igher in pregnant than non-pregnant women (17.3 +/- 5.8 vs 5.1 +/- 1.4 pmol /l mean +/- S.D.: P < 0.01), whereas CSF AM concentration did not differ be tween the two groups (1.3 +/- 0.9 and 0.9 +/- 0.4 pmol/l in groups P and NP respectively). No significant correlation was found between AM concentrati ons in the CSF and plasma. The present findings suggest that AM is present in the CSF and that its concentration in the CSF is regulated independently from that in the plasma.