Comparative study of sodium nitroprusside induced vasodilation of human placental veins from premature and full-term normotensive and preeclamptic pregnancy.

The objective of this study was to determine whether nitrovasodilator (nitric oxide donor) drug induced relaxation is different between preeclamptic and normotensive pregnancy. Human placental veins were collected at the time of delivery from normotensive (n = 6 premature, n = 6 full term) and preeclamptic (n = 6 premature, n = 3 full term) women and cut into rings. Cumulative concentration-response curves were performed on 5-hydroxytryptamine-contracted rings for the nitrovasodilator agent, sodium nitroprusside (SNP). The EC50 values were determined from the SNP concentration-response curves of the individual subjects, and were compared across gestational age and between preeclamptic and normotensive pregnancy by two-way ANOVA. There was no difference in the SNP EC50 values for normotensive and preeclamptic human placental veins in either the premature or full-term study groups. However, for both normotensive and preeclamptic pregnancy, the SNP EC50 value for full-term placental vein was greater than that for premature tissue. The sensitivity of human placental veins to SNP is similar between preeclamptic and normotensive pregnancy at similar gestational ages, but is increased in premature compared with full-term pregnancy in both preeclamptic and normotensive pregnant women.