Inhibition of nitric oxide synthesis in vascular smooth muscle by retinoids.
1. These studies examine the effect of retinoids on interleukin 1 beta (IL-1 beta)-induced nitric oxide synthase (NOS) activity in cultured rat aortic vascular smooth muscle (VSM) cells and isolated rat aortic rings. 2. All-trans-retinoic acid (all-trans-RA, 0.1-10 microM) and its active analogues produced concentration-dependent inhibition of IL-1 beta (0.1-10 ng ml-1)-induced nitrite production in cultured VSM cells. In contrast, the inactive retinoid, Ro 14-6113 (0.1-10 microM), had no effect on IL-1 beta-induced nitrite production. 3. Since some of the actions of retinoids are mediated by induction of transforming growth factor beta (TGF-beta), its effect on inducible NOS activity in VSM cells was examined. TGF-beta produced concentration-dependent (0.1-10 ng ml-1) inhibition of IL-1 beta-induced nitrite production and the maximum effect (approximately 90% inhibition) was significantly greater than that seen with all-trans-RA (approximately 70% with 10 microM). However, an anti-TGF-beta antibody (50 micrograms ml-1) which blocked the effect of exogenous TGF-beta (5 ng ml-1) did not significantly reverse the inhibitory action of all-trans-RA (10 microM). 4. In addition to inhibiting IL-1 beta-induced nitrite production, all-trans-RA (10 microM) reduced substantially inducible NOS mRNA and protein levels in IL-1 beta-induced VSM cells (P < 0.01). 5. Incubation of isolated rat aortic rings with IL-1 beta (10 ng ml-1) caused a progressive resistance of the rings to the vasoconstrictor action of phenylephrine (10 nM to 10 microM). This effect was abolished by the addition of the nitric oxide synthase inhibitor L-NG-monomethyl-L-arginine (L-NMMA, 1 mM). All trans-RA (10 micro M) also markedly and significantly reversed this IL-1p-induced vascular hyporeactivity(P<0.01).6. These data show that all-trans-RA and other active retinoids are able to block cytokine-stimulated expression of inducible NOS in cultured VSM cells and isolated aortic rings.
Hirokawa
K
K
Department of Clinical Pharmacology, Royal Postgraduate Medical School, London.
O'Shaughnessy
K M
KM
Ramrakha
P
P
Wilkins
M R
MR
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D008297:Male; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase; D016133:Polymerase Chain Reaction; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012176:Retinoids / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology
D007375:Interleukin-1; D012176:Retinoids; D016212:Transforming Growth Factor beta; D009569:Nitric Oxide; D014212:Tretinoin; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D012194:RNA-Directed DNA Polymerase