Extracellular superoxide dismutase localization and activity within the human placenta

Area of Science:

• Biochemistry
• Physiology
• Obstetrics

Background:

• Nitric oxide (NO) maintains low placental vascular tone but is rapidly inactivated by superoxide anion (O2-).
• Superoxide dismutases (SODs) scavenge O2-, thus preserving NO's vasodilatory effects.
• Extracellular superoxide dismutase (EC-SOD) is proposed to enhance NO bioavailability in systemic arteries, but its role in placental vasculature is unknown.

Purpose of the Study:

• To determine the localization and activity of EC-SOD in the human placenta.
• To compare placental EC-SOD in normal and pre-eclamptic pregnancies.
• To investigate EC-SOD's potential role in pre-eclampsia-related vascular dysfunction.

Main Methods:

• Immunohistochemical localization of EC-SOD in placental villous tissue.
• Measurement of EC-SOD activity in placental samples from normal and pre-eclamptic women.
• Comparison of EC-SOD distribution and activity between the two groups.

Main Results:

• Placental EC-SOD was localized to the extracellular matrix surrounding villous arterioles.
• No significant differences in EC-SOD distribution were observed between normal and pre-eclamptic placentas.
• Placental EC-SOD activity was comparable in both normal (33.7+/-4.1 center, 34.3+/-5.6 peripheral) and pre-eclamptic (33.1+/-2.5 center, 34.0+/-3.5 peripheral) subjects.

Conclusions:

• EC-SOD is present in the human placenta, localized around villous vessels, suggesting a protective role against O2- in fetal vasculature.
• Placental EC-SOD distribution and activity are not altered in pre-eclampsia.
• These findings indicate that EC-SOD is unlikely to be involved in the vascular pathophysiology of pre-eclampsia.