Morphological alterations in endothelial cells from human aorta and umbilical vein induced by forskolin and phorbol 12-myristate 13-acetate: a synergistic action of adenylate cyclase and protein kinase C activators.

The morphological effects on human endothelial cells of phorbol 12-myristate 13-acetate (PMA) and of agents that increase intracellular cAMP concentration were studied. The adenylate cyclase activator forskolin (10 microM), the cyclic nucleotide phosphodiesterase inhibitor methylisobutylxanthine (100 microM), dibutyryl-cAMP (10 microM), histamine (10 microM), and PMA (0.1 microM) significantly altered the morphology of human aortic and umbilical vein endothelial cells in primary cultures. These effects reached a maximum 40-80 min after the effector addition and became negligible 30-60 min after its removal. PMA and forskolin were strongly synergistic in altering endothelial cell morphology. All the effects of cAMP-elevating compounds and of PMA were abolished completely by 1 microM colchicine. In explants taken from human adult or child aortas, forskolin and PMA produced alterations in endothelial morphology qualitatively identical to those observed in endothelial cell cultures. Endothelium in these preparations closely resembled that found in zones of expected altered hemodynamic stresses of human aorta. Our data suggest that the morphology of endothelium in vivo may be regulated by separate or synergistic action of hormone-dependent adenylate cyclase and of inositol phospholipid turnover systems and might be important for maintenance of endothelial monolayer integrity under normal physiological and pathological conditions.