Neuropeptide Y enhances permeability across a rat aortic endothelial cell monolayer

Previously, in vivo studies showed that neuropeptide Y (NPY) elevates vascular permeability in isolated lung perfusion preparations, possibly through binding to the NPY Y3 receptor. The present study used monolayers in a double-chamber culture method under conditions of normoxia (5% CO2-20% O2-75% N2) or hypoxia (5% CO2-5% O2-90% N2) to test the hypothesis that NPY directly affects rat aortic endothelial cells (RAECs). RAECs were cultured on the base of the upper chamber, into which FITC-labeled albumin was introduced, and permeation into the lower chamber was measured. The RAEC monolayer was treated with 10–8–3 × 10–7 M NPY for 2 h in normoxia or hypoxia. In hypoxia, NPY concentration dependently increased the permeability of the RAEC monolayer, whereas in normoxia no significant change was observed. Peptide YY, NPY Y1, and NPY Y2 receptor agonists and NPY Y1 receptor antagonist exerted no significant effects under hypoxic conditions. NPY-(18–36), an NPY Y3 receptor antagonist, elicited an inhibitory act...