The in vitro effect on arterial wall function of serum from patients with pregnancy-induced hypertension.

The object of this study was to develop an in vitro model to identify the serum factor(s) responsible for the vascular changes that occur in pregnancy-induced hypertension (preeclampsia). Segments of rabbit carotid artery were perfused for 3 hours with nutrient medium to which serum from normal pregnant women or patients with preeclampsia was added. After perfusion, ring segments of the vessels were cut and mounted in muscle chambers for force measurement. Sensitivity of the vessels to constrictor agents and endothelium-mediated relaxation was studied. The results indicate that arteries exposed to serum from preeclamptic patients developed a 2.9-fold increase in sensitivity to angiotensin II, 1.6-fold increased sensitivity to norepinephrine, and no change of sensitivity to serotonin. These effects were not accompanied by changes in isometric force. Endothelium-mediated relaxation was not affected by serum from preeclamptic patients. These findings confirm clinical observations of increased angiotensin II sensitivity in preeclampsia. The system used may facilitate identification of factors that cause the difference between the sera of normal pregnant women and those with preeclampsia.