Protein kinase inhibitor attenuates an increase in endothelial monolayer permeability induced by tumour necrosis factor‐α

We questioned the mechanism of the increase in pulmonary endothelial permeability induced by tumour necrosis factor-alpha (TNF-alpha), a cytokine implicated in the pathogenesis of adult respiratory distress syndrome. As a measure of permeability, we determined the albumin transferred across cultured pulmonary endothelial monolayers prepared on a porous filter. The agents evaluated included protein kinase inhibitors H-7 and H-8, a calmodulin antagonist W-7, and protein kinase C (PKC) activators, phorbol myristate acetate (PMA) and SC-9. H-7, more potent in inhibiting PKC than H-8, failed to attenuate the increase in permeability induced by TNF-alpha. Neither PMA nor SC-9 increased permeability. However, H-8, which is a potent inhibitor of cyclic nucleotide-dependent protein kinases, prevented the increase in permeability induced by TNF-alpha. These results suggest that protein kinase other than PKC are involved in the signal transduction in endothelial permeability increase induced by TNF-alpha. Calmodulin pathway may not be implicated in the increase in permeability induced by TNF-alpha.