Microvascular vasodilator response to acetylcholine is increased in women with pre-eclampsia

Objectives To evaluate in vivo microvascular responses to incremental doses of the endothelial-dependent vasodilator, acetylcholine, and the endotheli al-independent vasodilator, sodium nitroprusside, in women with pre-eclamps ia and gestation-matched normotensive pregnant controls. Design Prospective clinical study. Setting Southern Derbyshire Acute Hospitals Trust, and University of Nottin gham Division of Vascular Medicine. Population Thirteen women with pre-eclampsia and 16 normotensive pregnant c ontrols. Methods Cutaneous microvascular vasodilator responses to iontophoretic admi nistration of incremental doses of acetylcholine and sodium nitroprusside ( 25-100 muC) were evaluated under temperature-controlled conditions using la ser Doppler fluximetry. Results Resting skin temperature and blood flow were similar among 13 women with pre-eclampsia [mean blood pressure 151/93 mmHg (4/3); mean gestation 35.6 weeks (1.0); and mean proteinuria 1.1 g/24h (0.2)] and 16 normotensive pregnant controls [mean blood pressure 111/63 mmHg (2/2); mean gestation 3 4.3 weeks (0.9)]. Peak vasodilator responses to acetylcholine were increase d in women with pre-eclampsia (median flux ratio 15.1 [IQR 12.3-17.6] vs 11 .7 [IQR 8.4-12.6], P < 0.05), whereas sodium nitroprusside responses were n ot different between the two groups: 11.4 [IQR 8.6-13.4] vs 9.5 [IQR 8.0-12 .3]. Conclusion In vivo microvascular vasodilator responses to acetylcholine are increased in women with preeclampsia, while endothelial-independent vasodi lation is unchanged. Although the mechanism of acetylcholine induced vasodi lation in small vessels is unclear, this study confirms previous animal dat a and provides in vivo evidence of altered microvascular endothelial cell f unction in pre-eclampsia.