p38 MAPK and Ca2+ contribute to hydrogen peroxide-induced increase of permeability in vascular endothelial cells but ERK does not

To examine the involvement of p38 mitogen-activated protein kinase (p38 MAP K) and extracellular signal-regulated kinase (ERK) in the oxidative stress- induced increase of permeability in endothelial cells, the effects of a p38 MAPK inhibitor (SB203580) and ERK inhibitor (PD90859) on the H2O2-induced increase of permeability in bovine pulmonary artery endothelial cells (BPAE C) were investigated using a two-compartment system partitioned by a semi-p ermeable filter. H2O2 at 1 mM caused an increase of the permeation rate of fluorescein isothiocyanate (FITC)-labeled dextran 40 through BPAEC monolaye rs. SB203580 inhibited the H2O2-induced increase of permeability but PD9805 9 did not, though activation (phosphorylation) of both p38 MAPK and ERK was observed in H2O2-treated cells in Western blot analysis. An H2O2-induced i ncrease of the intracellular Ca2+ concentration ([Ca2+](i)) was also observ ed and an intracellular Ca2+ chelator (BAPTA-AM) significantly inhibited th e H2O2-induced increase of permeability. However, it showed no inhibitory e ffects on the H2O2-induced phosphorylation of p38 MAPK and ERK. The H2O2-in duced increase of [Ca2+](i) was not influenced by SB203580 and PD98059. The se results indicate that the activation of p38 MAPK and the increase of [Ca 2+](i) are essential for the H2O2-induced increase of endothelial permeabil ity and that ERK is not.