RT Journal Article
SR Electronic
T1 Hypertonicity Inhibits Lipopolysaccharide-Induced Nitric Oxide Synthase Expression in Smooth Muscle Cells by Inhibiting Nuclear Factor κB
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1238
OP 1247
DO 10.1124/mol.63.6.1238
VO 63
IS 6
A1 Sandeep C. Pingle
A1 Joseph F. Sanchez
A1 Daniel M. Hallam
A1 Andrea L. Williamson
A1 Sanjay B. Maggirwar
A1 Vickram Ramkumar
YR 2003
UL http://molpharm.aspetjournals.org/content/63/6/1238.abstract
AB The expression of inducible nitric-oxide synthase (iNOS) in vascular smooth muscle cells leads to prolonged vasorelaxation in vivo and contributes to the profound vasodilation induced by bacterial lipopolysaccharide (LPS) in septic shock. This induction of iNOS depends, in large part, on activation of nuclear factor (NF)-κB. Hypertonicity regulates the activity of NF-κB in different cell lines; as such, we propose that it should also regulate the expression of iNOS. Thus, the goal of this study was to determine whether hypertonicity regulates iNOS expression and function in smooth muscle cells and to elucidate the mechanism(s) underlying this process. Treatment of hamster ductus deferens (DDT1MF-2) cells and porcine aortic smooth muscle cells with either mannitol (50 mM) or NaCl (50 mM) reduced LPS-stimulated iNOS expression and nitric oxide release. Both of these agents also reduced the activation of NF-κB induced by LPS, tumor necrosis factor-α and interleukin-1β in smooth muscle cells. This inhibitory action was caused by suppression of IκB-α phosphorylation, a prerequisite for ubiquitination and degradation of this protein, and showed additivity with N-benzoyloxycarbonyl (Z)-Leu-Leu-leucinal (MG-132), an inhibitor of proteasomal degradation of IκB-α. Furthermore, exposure to mannitol inhibited the activity of IκB kinase, an enzyme involved in phosphorylation of IκB-α. Mannitol was unable to affect the induction of iNOS produced by overexpression of RelA in DDT1MF-2 cells, suggesting that this agent does not have additional downstream inhibitory actions on this activated NF-κB subunit. Taken together, these data suggest that these hypertonic solutions may prove useful as anti-inflammatory agents, especially against conditions associated with increased NF-κB activity.