Inhibitory effect of erythropoietin on contractility of human chorionic plate vessels

Objective: Placenta is a major source of erythropoietin production in the fetus; hypoxia is associated with elevated erythropoietin levels in the fetal circulation. We investigated fetoplacental vascular reactivity after exposure to erythropoietin in vitro. Study design: Third-order chorionic plate arteries from human term placentae were incubated in culture medium with or without erythropoietin (3 U/mL) for 24 hours. Vessels were mounted in a myograph for isometric tension recording, and their responses to vasopressors and vasorelaxants were studied. Results: Contractile responses to endothelin-1 and the thromboxane analogue U46619 were decreased in erythropoietin-exposed vessels compared with controls. Relaxant responses to the nitric oxide donor sodium nitroprusside and the phosphodiesterase inhibitor papaverine were not influenced by erythropoietin. Conclusion: Exposure to elevated levels of erythropoietin has an inhibitory effect on contractile responses in human placental chorionic plate arteries. We speculate that this may improve fetoplacental perfusion in hypoxic fetuses with elevated erythropoietin production.