Endothelin modulation of tissue plasminogen activator release from human vascular endothelial cells in culture.
To clarify a possible involvement of the vasoconstrictive peptide endothelin in the regulation of endothelial cell-mediated fibrinolytic system, confluent cultures of vascular endothelial cells from human umbilical vein were incubated in serum-free medium in the presence of endothelin-1 at 100 nM and below, and tissue plasminogen activator antigen (t-PA:Ag) in the medium was determined by enzyme immunoassay. Endothelin-1 at 1 nM and above significantly decreased the release of t-PA:Ag from the endothelial cells after a 24 h incubation. The t-PA:Ag release was also decreased by either endothelin-2 or endothelin-3 at 10 nM. The activity of lactate dehydrogenase in the medium was not changed by endothelin-1 at 100 nM and below, suggesting that the peptide did not cause nonspecific cell damage. The decrease in the t-PA:Ag release induced by endothelin-1 occurred in the presence or absence of 8-bromo cyclic AMP, which is an active congener of cyclic AMP; 3-isobutyl-1-methylxanthine, which is an inhibitor of phosphodiesterase; and forskolin, which is a stimulator of adenylate cyclase. These results strongly indicated that cyclic AMP which is known to down-regulate t-PA:Ag release was not involved in the endothelin-1 effect. However, endothelin-1 failed to decrease the t-PA:Ag release in the presence of either calcium ionophore A23187 or EGTA; the ionophore itself markedly decreased the release. The cytosolic calcium accumulation was significantly increased by endothelin-1. These results suggest that endothelin-1 decreases the release of t-PA:Ag from human endothelial cells through an excess accumulation of intracellular, especially cytosolic which would be mediated by an extracellular, calcium-dependent mechanism.
Kaji
T
T
Department of Environmental Science, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
Yamamoto
C
C
Sakamoto
M
M
Koizumi
F
F
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D016232:Endothelins / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005342:Fibrinolysis / Q000502:physiology*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D016232:Endothelins; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000001:Calcimycin; D004533:Egtazic Acid; D007770:L-Lactate Dehydrogenase; D010959:Tissue Plasminogen Activator; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine