Hypertonic saline solution induces prostacyclin production by increasing cyclooxygenase-2 expression.
BACKGROUND
Previously, we demonstrated that hypertonic saline solution (HTS) and endotoxin (lipopolysaccharide [LPS]) induce prostacyclin (PGI(2)) production in human endothelial cells. Here, we hypothesized that HTS and LPS may induce PGI(2) production by increasing cyclooxygenase (COX) expression. We further examined the activation of p38 and extracellular signal-regulated kinases (ERK) and questioned whether these transduction cascades might mediate COX expression.


METHODS
Human umbilical vein endothelial cells were stimulated with varying concentrations of NaCl or LPS.


RESULTS
HTS and LPS induced prompt activation of both p38 and ERKs that peaked at 30 minutes. HTS and LPS also induced a dose-related increase in COX-2 with maximal expression within 4 to 6 hours; there was no change in COX-1. This correlated with an increase in supernatant PGI(2) levels, which became statistically significant for NaCl of more than 40 mmol/L and for all LPS doses. The inhibition of p38 with SB202190 abrogated the osmotic and LPS-induced COX-2 expression and PGI(2) production. Inhibition of ERK activation had no effect on COX-2 expression.


CONCLUSIONS
Hyperosmolarity and LPS induce, in chronologic order, p38 and ERK activation, COX-2 expression, and PGI(2) production. Because COX is the rate-limiting enzyme in prostaglandin synthesis, it is likely that the increase in PGI(2) production is due to, at least in part, the increased COX-2 expression. The data also suggest that p38 mitogen-activated protein kinase is involved in the signaling cascade for COX-2 expression.
Arbabi
S
S
Department of Surgery, University of Washington, Seattle 98104, USA.
Rosengart
M R
MR
Garcia
I
I
Maier
R V
RV
D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000096:biosynthesis*; D004926:Escherichia coli; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D014471:Umbilical Veins
D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D011725:Pyridines; D012462:Saline Solution, Hypertonic; D011464:Epoprostenol; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one