Effects of vasoactive agents on isolated human umbilical arteries in preeclamptic women treated with magnesium sulfate: a preliminary report.
Increased vascular reactivity has been noted in preeclampsia. It is uncertain whether this increased reactivity extends to the umbilical circulation. Helical strips of human umbilical arteries from 12 preeclamptic and 17 control patients were set up isometrically in physiological solution. Four preeclamptics who had not received magnesium were included. The resting tensions of the strips, amplitudes, frequencies, and times of onset of spontaneous contractions during the incubation period were noted and did not differ between the groups. When logarithmic dose contractile-response curves were made for serotonin, bradykinin, and KCl for each group, differences were noted only for KCl. The threshold dose for KCl was higher in tissues from the preeclamptic group (8.52 +/- 0.96 mM) compared to the controls (4.09 +/- 0.59 mM) regardless of magnesium therapy. Also, the ED50 for KCl was higher for preeclamptics given magnesium (12.45 +/- 1.21 mM) compared to controls (9.17 +/- 1.05 mM). There were no significant differences between maximal tensions obtained, but a trend was noted for preeclamptics who did not receive magnesium to develop less tension than either controls or preeclamptics who did receive magnesium, regardless of the agonist tested. Relaxation times differed only for KCl, where there was a shortening of the time for the preeclamptics (8.76 +/- 0.64 min) compared to controls (14.53 +/- 2.46 min). These results do not support other studies in which an increased peripheral vascular reactivity in preeclamptics was noted. An explanation for the decreased reactivity to KCl awaits further investigation.
Handwerker
S M
SM
Department of Physiology, SUNY Health Science Center, New York, N.Y.
Halevy
S
S
Altura
B M
BM
D000328:Adult; D001920:Bradykinin / Q000494:pharmacology; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007537:Isometric Contraction / Q000187:drug effects; D008278:Magnesium Sulfate / Q000378:metabolism / Q000627:therapeutic use*; D011189:Potassium Chloride / Q000494:pharmacology; D011225:Pre-Eclampsia / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D011247:Pregnancy; D012701:Serotonin / Q000494:pharmacology; D014469:Umbilical Arteries / Q000187:drug effects* / Q000503:physiopathology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D014662:Vasoconstrictor Agents; D012701:Serotonin; D011189:Potassium Chloride; D008278:Magnesium Sulfate; D001920:Bradykinin