Nitric oxide inhibitor N omega -nitro-l-arginine methyl ester potentiates induction of heme oxygenase-1 in kidney ischemia/reperfusion model: a novel mechanism for regulation of the oxygenase.
The biological significance of the heme oxygenase (HO) system's response to stress reflects functions of its products-CO and bile pigments. CO is a messenger molecule, whereas bile pigments are antioxidants and modulators of cell signaling. Presently, an unexpected mechanism for sustained suprainduction of renal HO-1 following ischemia/reperfusion injury is described. Inhibition of nitric-oxide synthase (NOS) activity by Nomega-nitro-l-arginine methyl ester (l-NAME) at the resumption of reperfusion of rat kidney subjected to bilateral ischemia (30 min) was as effective as the most potent HO-1 inducer, the spin trap agent n-tert-butyl-alpha-phenyl nitrone (PBN), in causing sustained suprainduction of HO-1 mRNA. PBN forms stable radicals of oxygen and nitrogen. Twenty-four hours after reperfusion, HO-1 mRNA measured approximately 30-fold that of the control in the presence of l-NAME treatment; in its absence, the transcript increased to only approximately 5-fold. At 4 h in the presence or absence of the l-NAME HO-1, mRNA was increased by approximately 30-fold. The transcript was translated to active protein as indicated by Western blotting, immunohistochemistry, and activity analyses. l-NAME was not effective given 1 h after resumption of reperfusion. Suprainduction was restricted to the kidney and not detected in the heart and aorta; ferritin expression in the kidney was not effected. It is reasoned that in tissue directly insulted by ischemia/reperfusion, increased production of NO radicals promotes the loss of HO-1 transcript. Because the absence of NO radicals and presence of PBN had a similar effect on HO-1, we propose that suprainduction of the gene is mainly caused by O2 radicals formed on reperfusion. Inhibition of NOS is potentially useful for sustained induction of HO-1 in organs that will be subjected to oxidative-stress insult.
Mayer
Robert D
RD
Department of Urology, University of Rochester Medical Center, Rochester, NY 14642, USA.
Wang
Xiaojun
X
Maines
Mahin D
MD
D000818:Animals; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis*; D051547:Heme Oxygenase-1; D007674:Kidney Diseases / Q000201:enzymology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D010105:Oxygenases / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000201:enzymology*
D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D009569:Nitric Oxide; D010105:Oxygenases; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D019331:NG-Nitroarginine Methyl Ester