Inhibition of iNOS with S-methylisothiourea was impaired in wound healing in caustic esophageal burn.
OBJECTIVE
Stricture formation is a late complication of caustic esophageal burn, which is a common problem in childhood. For this reason, this experimental study was designed to observe the possible effect of nitric oxide on healing and fibrosis formation in caustic esophageal burns.


METHODS
The rats were divided into five groups. Group A (n=12) received sham burn and treatment with saline injection. Group B (n=34) received caustic burn. Rats in group C (n=31), were given water supplement with 10 g/L L-arginine that was started 24 h preoperatively and continued until postoperative day 4. In group D (n=21), S-methylisothiourea (SMT, specific inducible nitric oxide synthase (iNOS) inhibitor), was injected at a dose of 3 mg/kg i.p. at 30 min before caustic burn, and similar dose was reinjected immediately after caustic burn. SMT 6 mg/kg/day injections continued for 4 days long. In group E (n=22), Nomega-nitro-L-arginine (L-NNA, nonspecific nitric oxide synthase (NOS) inhibitor) was injected at a dose of 15 mg/kg i.p. at 30 min before caustic burn, and similar dose was reinjected immediately after caustic burn. L-NNA 30 mg/kg/day continues for 4 days.


RESULTS
Dead rates were significantly higher in group E than in groups A-D. The mean hydroxyproline levels in esophageal tissue were significantly lower in groups A and B than in group D. Histopathologically, tissue damage scores in the esophageal tissue were higher in group D than in groups A-C.


CONCLUSIONS
Inhibition of iNOS with SMT was impaired in wound healing due to caustic esophageal burn and provoked collagen accumulation at a later period. Those effects may due to inhibition of antioxidant, immunomodulatory and antifibrotic effects of NO.
Basaran
Umit Nusret
UN
Department of Pediatric Surgery, Medical Faculty, Trakya University, Edirne, Turkey. umitnb@superonline.com
Eskiocak
Sevgi
S
Altaner
Semsi
S
Ture
Mevlut
M
Yapar
Suleyman Bedir
SB
D000818:Animals; D002057:Burns, Chemical / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004947:Esophagus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006909:Hydroxyproline / Q000378:metabolism; D007550:Isothiuronium / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015996:Survival Rate; D016896:Treatment Outcome; D014945:Wound Healing / Q000187:drug effects*
D004791:Enzyme Inhibitors; D019335:Nitroarginine; D007550:Isothiuronium; D052247:Nitric Oxide Synthase Type II; C027744:S-methylisothiopseudouronium; D006909:Hydroxyproline