Thrombin triggers the de novo expression of an inducible NO synthase in porcine aortic valve endothelial cells.
The nitric oxide (NO) production by porcine aortic valve endothelial cells was estimated in cusps incubated at 37 degrees C by measuring their cyclic GMP content and the nitrite levels of the incubation medium. After a stabilization period, incubation for 5 min with acetylcholine, bradykinin, ADP and bovine thrombin resulted in a receptor-mediated increase in cyclic GMP which could be blocked by EGTA, N-omega-nitro-L-arginine methyl ester (L-NAME) and NG-monomethyl-L-arginine (L-NMMA). Incubation with lipopolysaccharide (endotoxin) from E. coli O111:B4 or bovine for 5 h, dose-dependently increased nitrite production as well as cyclic GMP content. The elevated nitrite production was completely abolished in the presence of the protein synthesis inhibitor cycloheximide, was reduced by more than 50% by dexamethasone but was not affected by EGTA. L-NMMA dose-dependently reduced the increased nitrite production and cyclic GMP content. These results suggest that besides the presence of a constitutive NO synthase in porcine aortic valve endothelial cells thrombin, like lipopolysaccharide, triggers the de novo expression of an inducible Ca(2+)-independent NO synthase.
De Meyer
E
E
Divisions of Pharmacology, Faculty of Medicine, University of Antwerp (UIA), Wilrijk, Belgium.
Van Hove
C E
CE
Feng
X J
XJ
Rampart
M
M
Herman
A G
AG
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000201:enzymology*; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D019331:NG-Nitroarginine Methyl Ester; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000378:metabolism*; D013552:Swine; D013917:Thrombin / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D001120:Arginine; D019001:Nitric Oxide Synthase; D013917:Thrombin; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester