Vascular smooth muscle oxygen consumption is reversibly stimulated by sera from women with preeclampsia.

OBJECTIVE

Preeclampsia is a complication of pregnancy that causes maternal vasoconstriction and hypertension. The disease may progress to eclampsia, which is thought to be related to cerebral vasospasm. Although there is evidence for more than one circulating factor that causes endothelial cell dysfunction in preeclampsia, little work has focused on the possibility that vascular smooth muscle function might be directly stimulated by a circulating factor. The aim of this study was to determine whether such a factor or factors could be detected by the vessels.

STUDY DESIGN

Excessive vascular smooth muscle oxygen consumption was used as a screen for metabolic stimulation because pathologic arterial constriction would require oxidative metabolism to generate adenosine triphosphate. De-endothelialized porcine carotid artery (a well-validated model of human arterial contractile function) was exposed to sera from patients with preeclampsia (1:30 dilution) in a sealed chamber with an oxygen electrode, and the rate of oxygen consumption by the tissue was measured. Comparisons with the effects of sera from matched normal pregnant patients and from nonpregnant women were made.

RESULTS

Exposure of vascular smooth muscle to sera from women with preeclampsia for 90 minutes resulted in greater oxygen consumption by the tissue (0.66 +/- 0.16 micromol O2 /min per gram of dry weight) than did exposure to sera of matched pregnant and nonpregnant control subjects (0.34 +/- 0.08 micromol O2 /min per gram of dry weight, P <.001, and 0.29 +/- 0.03 micromol O2 /min per gram of dry weight, P <.001, respectively). This stimulation was completely reversed by rinsing.

CONCLUSIONS

There is a factor in the circulation of women with preeclampsia that has the reversible effect on vascular smooth muscle of accelerating oxygen consumption. We discuss the implications of this observation in terms of known aspects of vascular smooth muscle contractile function.