Loss of endothelium-dependent relaxation in myometrial resistance arteries in pre-eclampsia.

OBJECTIVE

To measure endothelium-dependent relaxation in myometrial resistance arteries and to compare this parameter in nonpregnant and normotensive pregnant women and those with pregnancies complicated by pre-eclampsia.

DESIGN

A prospective study.

SETTING

Nottingham City Hospital.

SAMPLE

Thirty-seven nonpregnant women undergoing hysterectomy and 51 pregnant women undergoing caesarean section, of whom there were 39 normotensive and 12 with pre-eclampsia.

METHODS

Resistance arteries, dissected from myometrial biopsies, were mounted on a wire myograph and preconstricted with vasopressin then subjected to incremental doses of bradykinin.

RESULTS

Endothelium-dependent relaxation to bradykinin was seen in the vessels of nonpregnant and normotensive pregnant women. Markedly reduced endothelium-dependent relaxation was found in the myometrial arteries from women with pre-eclampsia when compared with both nonpregnant (P < 0.0001) and normotensive pregnant (P < 0.0001) women.

CONCLUSION

A significant loss of endothelium-dependent relaxation in myometrial resistance arteries in pre-eclampsia may contribute to the altered vasoreactivity seen in pre-eclampsia, and particularly to the decreased placental perfusion and fetal growth retardation commonly associated with this condition.