title: Secondary ischemic tolerance improved by administration of L-NAME in rat flaps.
abstract: Nitric oxide (NO) under basal conditions is an important regulator of vascular tone. Under ischemic conditions, however, NO can combine with superoxide anion to produce the damaging hydroxyl free radical. The current project observes the effect of inhibiting NO production (L-Nitro-amino-methyl-arginine, L-NAME) on flaps rendered ischemic by secondary (2 degrees) venous obstruction. Eighty rats had 3 x 6 cm skin flaps based on the epigastric vessels. Primary (1 degree) ischemia was produced by arteriovenous occlusion for 2 hours; (2 degrees) venous ischemia was induced by clamping the vein, alone for either 3 or 5 hours. Thirty minutes prior to 2 degrees ischemia, rats received either L-NAME (30 mg/kg) or saline buffer. Flap survival was assessed 7 days later and Chi-square analysis was used. At 3 hours of ischemia, treatment improved survival from 55% to 85% (P < 0.05). Treatment also improved survival at 5 hours of ischemia from 5% to 35% (P < 0.04). Although under resting conditions, NO is a potent vasodilator, during 2 degrees venous obstruction it may contribute to flap necrosis.
authors.affiliation: University of Virginia Health Sciences Center, Department of Plastic Surgery, Charlottesville, USA.
authors.forename: L K
authors.initials: LK
authors.lastname: Knox
authors.forename: M F
authors.initials: MF
authors.lastname: Angel
authors.forename: T
authors.initials: T
authors.lastname: Gamper
authors.forename: L R
authors.initials: LR
authors.lastname: Amiss
authors.forename: R F
authors.initials: RF
authors.lastname: Morgan
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000627:therapeutic use*; D009569:Nitric Oxide / Q000009:adverse effects* / Q000096:biosynthesis / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000517:prevention & control*; D013524:Surgical Flaps / Q000098:blood supply*
chemical_list: D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester