Functional implications of cAMP and Ca2+ on prostaglandin I2 and thromboxane A2 synthesis by human endothelial cells.
Human umbilical vein endothelial cells were incubated with ATP, ADP, thrombin, or ionophore A23187 for as long as 600 seconds. A statistically significant rise in the prostaglandin I2 (prostacyclin; PGI2) and thromboxane A2 (TxA2) release was observed after 45 seconds. The maximum amount of cytosolic free Ca2+ was reached between 20 and 30 seconds. A statistically significant elevation of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels was observed only in response to ATP and ADP after 120 seconds. Furthermore, adenosine, caffeine, phorbol 12-myristate 13-acetate (PMA), and adenosine 5'-(alpha, beta-methylene)triphosphate were tested alone or in combination with ATP or thrombin. PMA inhibited ATP-stimulated eicosanoid biosynthesis but had no effect on thrombin. Of the agents used to increase cytosolic free Ca2+ concentrations, only PMA failed to provoke eicosanoid release. Similarly, only PMA failed to induce a Ca2+ flux in the absence of extracellular Ca2+. The data presented show that PGI2 and TxA2 release from human umbilical cord endothelial cells is closely associated with Ca2+ mobilized from intracellular sources. Extracellular Ca2+, as well as changes in intracellular cAMP levels, has no influence on endothelial eicosanoid synthesis, at least for short-term regulation (less than or equal to 600 seconds).
Griesmacher
A
A
Second Department of Surgery, University of Vienna, Austria.
Weigel
G
G
David
M
M
Horvath
G
G
Mueller
M M
MM
D000241:Adenosine / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D011464:Epoprostenol / Q000096:biosynthesis*; D006801:Humans; D007700:Kinetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000096:biosynthesis*
D000001:Calcimycin; D002110:Caffeine; D013928:Thromboxane A2; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011464:Epoprostenol; D000242:Cyclic AMP; D013917:Thrombin; D000241:Adenosine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium