Characteristics of resistance vessels in pre-eclampsia and normotensive pregnancy.

Isolated omental resistance vessels from women with pre-eclampsia had an increased media thickness/lumen diameter ratio compared to similar vessels from normotensive pregnant women. The active and passive tension length curves for the two groups of vessels were similar and like the classical tension length curve for skeletal muscles. The maximal media stress (force per media cross-section) was also similar; however, calculating in terms of equivalent pressure (on basis of Laplaces law) indicated that the vessels in vivo would have been able to contract against an increased blood pressure. The results indicate that pre-eclampsia is associated with structural alterations of the resistance vessels which might be of importance for the haemodynamics of pre-eclampsia.