LOSS OF DOPAMINE D-1-LIKE RECEPTORS IN THE UMBILICAL ARTERY OF PREECLAMPTIC SUBJECTS

1 The influence of pre-eclampsia on the density and pattern of dopamin e D-1-like receptors was studied in frozen samples of the placental en d of the umbilical artery by using radioligand binding and autoradiogr aphic techniques in combination. 2 Analysis was performed on normotens ive (n = 10) and pre-eclamptic subjects (n = 9) undergoing caesarean d elivery, using [H-3]-SCH 23390 as a ligand. Preeclamptic patients rece ived a low salt diet and were treated with magnesium sulphate and hydr alazine. The possibility that this treatment may cause changes in the density of dopamine D-1-like receptors was evaluated by treating male Wistar rats in the same way and by determining [H-3]-SCH 23390 binding in sections of the kidney which represents an organ containing dopami ne D-1-like receptors. 3 The density of dopamine D-1-like receptors of the umbilical artery, which are probably vasodilatory, was decreased in pre-eclamptic compared with normotensive subjects. In contrast, the affinity of the radioligand for dopamine D-1-like receptors was not s tatistically different between normotensive and pre-eclamptic subjects . Low salt diet, magnesium sulphate and hydralazine treatment did not affect [H-3]-SCH 23390 binding to sections of rat kidney. This suggest s that changes in the density of dopamine D-1-like receptors in pre-ec lamptic patients are a specific phenomenon not dependent upon antihype rtensive measures. 4 Analysis of the pharmacological profile of [H-3]- SCH 23390 binding to sections of the umbilical artery both in normoten sive and pre-eclamptic subjects indicates the labelling of dopamine D- 5 receptors. 5 These findings collectively suggest that the dopaminerg ic vasodilatory tone in the umbilical artery is impaired in pre-eclamp sia. The possible significance of these data should be clarified in fu ture studies.