Phorbol ester induces diaphragmed fenestrae in large vessel endothelium in vitro

The endothelium of visceral capillaries is fenestrated, whereas that of large vessels is not. We show here that the tumor promoter, 4 beta-phorbol 12-myristate 13-acetate (PMA), triggers formation of diaphragmed fenestrae in endothelial cells cultured from the calf pulmonary artery and the human umbilical vein. This demonstrates that large vessel endothelial cells have the potential to express, in response to exogenous signals, a structural specialization uniquely associated with the endothelium of visceral capillaries in vivo.