Cyclic AMP increases thrombomodulin expression on membrane surface of cultured human umbilical vein endothelial cells

Abstract Dibutyryl-cyclic AMP (Bt 2 cAMP; final concentration 1–5 mM) or beraprost sodium (synthetic prostacyclin, 100 nM) enhanced the expression of thrombomodulin (TM; an anticoagulant factor of endothelial cells) on the membrane surface of cultured human umbilical vein endothelial cells up to 1.4 times over the control within 9 hrs after the treatment, while the expression fell below the control level at 12 hrs and thereafter. 8-Bromo-cAMP (final concentration 1–5 mM) or 3-isobutyl-l-methylxanthine (IBMX; an inhibitor of phosphodiesterase; final concentration 10–1000 μM) enhanced the expression of TM on the cell surface at 12 hrs after the treatment. The enhancement of TM expression caused by Bt 2 cAMP was inhibited by incubation with phorbol 12-myristate 13-acetate. These results suggest that cAMP stimulates expression of TM in the endothelial cells.