Enhancement of barrier function of human aortic endothelial cells by activators of protein kinase C.

We investigated the role of protein kinase C (PKC) in regulating the permeability of human and bovine aortic endothelial cells (AECs) cultured on micropore filters. AECs cultured in the upper chamber were incubated with medium containing a PKC agonist, phorbol 12-myristate 13-acetate (PMA) or 1-oleoyl-2-acetyl-glycerol (OAG) for 15 min to 8 h, after which the cells were incubated with albumin for 1 h. The amount of albumin that had transferred through AECs was determined. Activation of PKC by exposure to PMA or OAG inhibited albumin permeability in human AECs, but increased it in bovine AECs. While the PKC inhibitor, staurosporine, did not itself influence endothelial permeability, it reduced the decrease or increase in permeability induced by exposure to PMA or OAG in human and bovine AECs, respectively. Activation of PKC thus enhanced the barrier function of human AECs, but reduced it in bovine AECs.