D.D. Houlihan, M.C. Dennedy, N. Ravikumar, J.J. Morrison
Anti-hypertensive therapy and the feto-placental circulation: effects on umbilical artery resistance
Objective: To investigate and compare the direct effects
of compounds used in the treatment of hypertensive disease
in pregnancy on human umbilical artery resistance
in vitro.
Methods: Isometric tension recordings were performed
under physiological conditions on human umbilical arterial
rings (n=30). The in vitro effects of labetolol, hydralazine,
alpha-methyldopa, nifedepine and magnesium
sulphate (at concentration ranges from 1 nanomolar to
1 millimolar), and their respective vehicle controls, were
measured. Results were expressed as ?logEC50 (pD2)
and mean maximal inhibition values for each compound.
Results: All compounds investigated, except alpha methyldopa,
exerted a significant relaxant effect on umbilical
arterial tone. Alpha-methyldopa was significantly less
potent when compared to all other compounds (mean
maximal inhibition value [20.89±7.99%] versus all other
agents [range 63.15±8.70?84.12±3.84%] (P<0.01)).
The dose response curve of nifedipine yielded a significantly
greater pD2 value when compared to that of
hydralazine, labetalol, and magnesium sulphate (pD2 value
[5.82±0.34] versus the above groups [range
3.10±0.09?3.52±0.14] (P<0.01)).
Conclusion: These findings demonstrate that agents
commonly used for the treatment of hypertensive disease
in pregnancy, excluding alpha-methyldopa, have
significant direct effects on the feto-placental circulation.
These results suggest that alpha-methyldopa administration
during pregnancy is less likely to produce significant
direct effects on fetal vasculature then other agents used.
Journal of Perinatal Medicine, Walter de Gruyter
Print ISSN: 1619-3997
Volume: 32, 07/2004
Pages: 315 - 319
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