In the dual perfused, single isolated cotyledon, human placental model, exposure of the maternal circulation to ephedrine and phenylephrine caused an increase in FAP, whereas exposure to norepinephrine, epinephrine, and methoxamine did not. The pharmacodynamic mechanisms underlying these differences have yet to be explained. Thus, the clinical implications of the findings are as yet unclear.
We investigated the characteristics of hypoxemic fetoplacental vasoconstriction (HFPV) in the dual perfused, single isolated human placental cotyledon. Fetal arterial blood pressures (FAP) were measured in four cotyledons (Group 1) equilibrated with 21% oxygen (O2), 5% carbon dioxide (CO2), and nitrogen (N2) [control] followed by 5% CO2 in N2 for 30 min. FAP (mean +/- sd) increased from 69.8 (+/- 6.4) to 105 (+/- 3.0) mm Hg (P < 0.05), confirming the utility of HFPV in the human placenta. Eight more cotyledons (Group 2) were exposed sequentially and alternately at 15-min intervals to the control gases and to gas blends containing 15%, 12%, 5%, and 0% O2 with 5% CO2 and N2. FAP increased significantly (P < 0.05) in a stepwise fashion from 68.7 (+/- 3.7) to 70.5 (+/- 3.3) mm Hg with 15% O2; from 69.3 (+/- 3.8) to 72.4 (+/- 4.3) mm Hg with 12% O2; from 67.8 (+/- 3.2) to 74.5 (+/- 3.4) mm Hg with 5% O2; and from 69.7 (+/- 3.4) to 77.9 (+/- 5.9) mm Hg with 0% O2, suggesting that HFPV is a graduated response to reduced O2 conditions in the human placenta.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.