Thrombin prevents the expression of inducible nitric oxide synthase in vascular smooth muscle cells by a proteolytically-activated thrombin receptor.
Proteolytically active forms of thrombin ( alpha- and gamma-thrombin) and thrombin receptor peptides inhibited the release of nitrite, a stable endproduct of nitric oxide, evoked by interleukin-1 beta (IL-1 beta ) in cultured vascular smooth muscle cells while proteolytically inactive forms [D-Phe-Pro-Arg chloromethyl ketone-alpha-thrombin (PPACK-alpha-thrombin) and diisopropylphosphoryl-alpha-thrombin (DIP-alpha-thrombin)] had either no or only minimal inhibitory effects. Under bioassay conditions, perfusates from columns containing IL-1 beta-activated vascular smooth muscle cells or cells treated with IL-1 beta plus PPACK-alpha-thrombin relaxed detector blood vessels. These relaxations were abolished by the inhibitor of nitric oxide synthesis, NG-nitro-L-arginine. No relaxations were obtained with untreated cells or IL-1 beta-treated cells in the presence of alpha-thrombin. The expression of inducible nitric oxide synthase mRNA and protein in vascular smooth muscle cells by IL-1 beta was impaired by alpha-thrombin. These results demonstrate that thrombin regulates the expression of the inducible nitric oxide synthase at a transcriptional level via the proteolytic activation of the thrombin receptor in vascular smooth muscle cells.
Schini-Kerth
V B
VB
Zentrum der Physiologie, Klinikum der JWG-Universität, Frankfurt, Germany.
Fisslthaler
B
B
Andersen
T T
TT
Fenton
J W
JW
Vanhoutte
P M
PM
Busse
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D002384:Catalysis; D002478:Cells, Cultured; D010450:Endopeptidases / Q000378:metabolism*; D004790:Enzyme Induction / Q000187:drug effects; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D009573:Nitrites / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018179:Receptors, Thrombin / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects
D009573:Nitrites; D018179:Receptors, Thrombin; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D010450:Endopeptidases; D013917:Thrombin