Objectives: To determine the degree of endothelium-dependent relaxation in myometrial and omental resistance arteries from normal pregnancies and pregnancies complicated with preeclampsia or fetal growth restriction (FGR) (compromised pregnancy group), and to correlate the results with the endothelial surface expression of cell adhesion molecules (CAMs) in the same vessels.
Methods: Parallel wire myography was used to assess the relaxation of omentum or myometrial vessels obtained from nonpregnant women (n = 3), women with normal pregnancies (n = 11), and women with pregnancies complicated by preeclampsia or fetal growth restriction (n = 10). These resistance vessels were constricted with incremental concentrations of vasopressin (10(-10) mol/L to 3.3 x 10(-8) mol/L) prior to the addition of incremental concentrations of bradykinin (10(-10) mol/L to 3.3 x 10(-6) mol/L). Immunohistochemistry was used to assess the endothelial expression of the CAMs E-selectin, ICAM-1, VCAM-1, and PECAM.
Results: A significant reduction in endothelium-dependent relaxation of myometrial vessels was found in the compromised pregnancy group when compared with both the normotensive pregnant group and the nonpregnant group. This reduction was not noted with omental vessels. All vessels in the nonpregnant group, normal pregnant group, and compromised pregnancy group expressed PECAM and ICAM-1 on the endothelium. There was no difference in intensity of immunostaining between the groups. None of the vessels in any of the groups expressed VCAM-1 or E-selectin.
Conclusions: We found no evidence that impaired relaxation responses to bradykinin are linked to altered expression of CAMs in preeclampsia and FGR. These results suggest that increased CAM expression occurs in a vascular bed separate from those investigated in the present study. Possible sites for this would be in the microcirculation of organs such as the kidney.