65 Insulin reverses endothelial dysfunction via A2B adenosine receptor activation in human umbilical vein endothelium from late-onset preeclampsia

Abstract

Preeclampsia courses with endothelial and insulin resistance. Insulin dilates umbilical vein requiring A2A adenosine receptor (A2AAR) activation in normal pregnancies; however, whether A2AAR are involved in late-onset preeclampsia (LOPE)-reduced insulin dilation is unknown. LOPE increases maternal and foetal plasma adenosine and A2BAR expression in human umbilical vein endothelial cells (HUVECs). A2BAR involvement and insulin effect on the foetoplacental vascular function in LOPE is unknown. Aim To evaluate A2AAR and A2BAR involvement on insulin effect on endothelial function in umbilical veins and HUVECs from LOPE. Methods Protein abundance (total and phosphorylated) of p44/42mapk, protein kinase B/Akt (Akt), endothelial nitric oxide synthase (eNOS) were detected by Western blot. Assays were in the absence or presence (8 h) of 1 nM insulin, 30 nM CGS21680 (A2AAR agonist), 10 nM ZM241385 (A2AAR antagonist), 0.1 nM BAY606583 (A2BAR agonist), or 30 nM MRS1754 (A2BAR antagonist). Vascular response to insulin (0.1–1000 nM, 5 min) was measured in preconstricted umbilical vein rings (wire myography) in the absence or presence of adenosine (1 mM) and/or A2AAR and A2BAR antagonists. L -Citrulline level was measured by HPLC in the absence or presence (8 h) of NG-nitro- L -arginine methyl ester (100 μM) in HUVECs. Results Insulin increased Akt (1.3 ± 0.1 fold), p44/42mapk (1.2 ± 0.1 fold), Ser1177 eNOS phosphorylation (1.2 ± 0.01 fold), and total eNOS protein abundance (1.5 ± 0.1 fold) in HUVECs from normal pregnancies. A2AAR and A2BAR activation enhanced insulin effect only on Akt (1.6 ± 0.1 fold). LOPE only increased Ser1177 eNOS phosphorylation and total eNOS protein abundance (2.2 ± 0.9 and 1.4 ± 0.2 fold, respectively). Insulin blocked LOPE-increased Ser1177 eNOS phosphorylation. A2AAR and A2BAR activation did not change insulin effect on Akt and p44/42mapk, whereas A2AAR antagonist reversed insulin-decreased Ser1177 eNOS phosphorylation and increased total eNOS protein abundance in LOPE. Insulin dilation of umbilical veins from normal pregnancies was lower (14 ± 2%, maximal relaxation (Rmax)) in the presence of A2AAR. LOPE reduced insulin dilation (18 ± 3% Rmax), which was restored by A2AAR antagonists. Insulin increased L -citrulline content (5.3 ± 0.3 fold), a phenomenon blocked by A2AAR and A2BAR antagonists in normal pregnancies. LOPE increased L -citrulline content, which was unaltered by insulin in absence of A2AAR and A2BAR antagonists. However, insulin increased L -citrulline content in the presence of A2AAR antagonists, but blocked by A2BAR antagonists in LOPE. Conclusion The reduced foetoplacental vascular response to insulin in LOPE involves A2AAR activation, a phenomenon counteracted by A2BAR activation.