Role of nitric oxide in human pulmonary microvascular endothelial cell adhesion

We examined the effect of nitric oxide (NO) on cell adhesion using cultured human pulmonary microvascular endothelial cells (PMVEC). Attachment of the se cells to fibronectin was significantly inhibited by NO donors, spermine NONOate and S-nitroso-N-acetyl-penicillamine or L-arginine, but not 8-bromo guanosine-3',5'-cyclic-monophosphate. Similar results were obtained with th e electrical cell-substrate impedance sensor (ECIS) technique. Addition of NO donors or L-arginine, but not 8-bromoguanosine-3',5' -cyclic-monophospha te or N-2,2'-O-dibutyrylguanosine-3',5'-cyclic-monophosphate, to confluent PMVEC monolayers resulted in a transient decrease in cell adhesion, which w as quantitated by the ECIS, Exposure to 1 U/ml alpha-thrombin reduced the m onolayer electrical resistance by similar to 50%. The observed response was significantly suppressed by pretreatment of cells with intracellular calci um chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'- acid or NO synthase i nhibitor, NG-nitro-L-arginine methyl ester, but not guanylate cyclase inhib itor, 6-anilino-5,8-quinoline-quinone. Selective knockout of endothelial NO synthase with antisense oligodeoxynucleotides also significantly reduced t hrombin-induced decrease in monolayer resistance. Our findings indicate tha t thrombin stimulates calcium-dependent release of NO from PMVEC, which med iates the retraction of endothelial cells via a cGMP-independent pathway. O ur results suggest that NO modulates cell-matrix and/or cell-cell adhesion in PMVEC and that this molecule might modify microvascular permeability in the human lune. (C) 2000 Elsevier Science Inc. All rights reserved.