Effects of vasoactive agents on isolated human umbilical veins in preeclamptic women.

Increased peripheral vascular reactivity has been noted in preeclampsia. However, in a recent study we found decreased reactivity to vasoactive agents in umbilical arteries of preeclamptic patients. A similar preliminary study, therefore, was carried out on umbilical veins to determine whether preeclampsia affected umbilical venous reactivity. Helical strips of human umbilical veins from 7 preeclamptic and 8 control patients were set up isometrically in physiological salt solution. The resting tensions did not differ between the groups, but spontaneous rhythmic contractions began much earlier in the preeclamptic group than in the controls (8.29 +/- 4.14 vs. 49.22 +/- 9.71 min). There were no differences in the mean amplitudes of the contractions at their time of onset, but in 5 patients of each group the mean amplitudes progressively rose to a maximum at approximately 90 min after incubation, and this maximum was significantly lower in the preeclamptic group (234.43 +/- 72.95 vs. 751.64 +/- 186.13 mg). The frequencies of the contractions did not vary with time or between groups. Log-dose response curves were made for serotonin and KCl, and there were no differences in threshold doses, ED50, maximal tensions or relaxation times between groups. These results are similar to those reported in human umbilical arteries from preeclamptic patients in that no increase in reactivity to vasoactive agents was noted. In conclusion, the differences in the spontaneous rhythmic contractions between preeclamptic patients and controls may be new evidence of pathological changes in the umbilical venous system in preeclampsia.