Rf. Figuerosa et al., ABSENCE OF RELAXATION TO LACTATE IN HUMAN PLACENTAL VESSELS OF PREGNANCIES WITH SEVERE PREECLAMPSIA, American journal of obstetrics and gynecology, 173(6), 1995, pp. 1800-1806
OBJECTIVE: Our objective was to determine whether the observed relaxat
ion to lactate and other agents in placental vessels of normal pregnan
cies is altered in severe preeclampsia. STUDY DESIGN: Isolated placent
al arteries and veins from women with severe preeclampsia and uncompli
cated term pregnancies were precontracted with prostaglandin F-2 alpha
under 5% oxygen and 5% carbon dioxide with the balance nitrogen (Po-2
35 to 38 torr) and then exposed to lactate (1 to 10 mmol/L, pH 7.4, n
= 8 to 15), arachidonic acid (0.01 to 10 mu mol/L, n = 6 to 13), nitr
oglycerin (1 nmol to 1 mu mol/L, n = 4 to 12), or forskolin (0.01 to 1
0 mu mol/L, n = 6 to 9). The response to lactate was also examined in
placental vessels from appropriate-for-gestational-age preterm deliver
ies (n = 8) for comparison with a similar group with severe preeclamps
ia (n = 8). The t test and analysis of variance statistics were used.
RESULTS: Relaxation to lactate was markedly inhibited in both placenta
l arteries and veins of women with severe preeclampsia compared with v
essels from uncomplicated term or preterm pregnancies. Responses to th
e other relaxing agents were not altered in the severely preeclamptic
vessels. CONCLUSIONS: In severe preeclampsia absence of lactate-induce
d dilatation of placental vessels may contribute to the fetal complica
tions associated with impaired blood flow and vasospasm.