Background: The present work aimed to study the changes of both norepinephrine (NE) and dopamine-beta-hydroxylase (DbetaH) in pregnancy-induced hypertension (PIH).
Methods: NE levels and DbetaH activity in blood were determined in 116 patients with pregnancy-induced hypertension and 40 normal control subjects using high performance liquid chromatography (HPLC) and ultraviolet (UV) spectrophotometry. Among patients with PIH, 28 were graded as mild, 34 moderate and 54 severe. The normal control subjects were selected from patients at a normal term pregnancy receiving elective cesarean section.
Results: NE levels and DbetaH activity in blood were significantly higher in patients with severe PIH than those in control subjects (p < 0.05 for both). Both patients and control subjects had higher NE levels and DbetaH activity in the umbilical artery blood than in the umbilical vein blood (p < 0.05). NE levels and DbetaH activity in both umbilical artery and vein blood were higher in the moderate and severe PIH groups than in the mild (p < 0.05) and control (p < 0.05) groups. NE levels in the umbilical artery blood were five times higher than those in the maternal blood, and DbetaH activity was three times higher. NE levels and DbetaH activity in the umbilical artery blood were significantly higher in the PIH group with complicated intrauterine growth retardation (IUGR) or fetal distress than in the PIH group without such complication.
Conclusions: The pathogenesis of PIH may relate to increase of excitability of the sympathetic nervous system in fetus.