Base Sequence, Cells, Cultured, Chloride Channels, Cystic Fibrosis Transmembrane Conductance Regulator, Endothelium, Vascular, Humans, Immunohistochemistry, Microcirculation, Molecular Sequence Data, Nucleotides, Cyclic, Patch-Clamp Techniques, Precipitin Tests, Pulmonary Circulation, RNA, Messenger, Reverse Transcriptase Polymerase Chain Reaction, Umbilical Veins