Effect of endogenous nitric oxide on hyperoxia and tumor necrosis factor-alpha-induced leukosequestration and proinflammatory cytokine release in rat airways.
OBJECTIVE
To investigate the effects of endogenous nitric oxide on hyperoxia and tumor necrosis factor-alpha-induced leukosequestration and proinflammatory cytokine release in rat airways.


METHODS
Prospective, randomized, controlled animal study.


METHODS
Experimental laboratory.


METHODS
Male Sprague-Dawley rats weighing 350-500 g.


METHODS
The rats were pretreated with N(G)-nitro-L-arginine methyl ester (L-NAME; 10 mg/kg) or saline intravenously 4-6 mins before intratracheal administration of tumor necrosis factor-alpha, 95% oxygen, or both, when the vasopressor effect of L-NAME had reached a plateau.


RESULTS
Bronchoalveolar lavage fluid was recovered from the airway of rats after exposure to 95% oxygen and tumor necrosis factor-alpha for 6 hrs under ventilator support. Neutrophils in lavage fluid were isolated and examined for the inducible nitric oxide synthase expression by flow-cytometric assay. Tumor necrosis factor-alpha and interleukin-1 beta in lavage fluid were measured by enzyme-linked immunosorbent assay. The percentage of neutrophils in bronchoalveolar fluid was significantly higher in rats exposed to hyperoxia + tumor necrosis factor-alpha (29.7 +/- 12.5%) compared with rats with hyperoxia (16.3 +/- 1.2%), tumor necrosis factor-alpha (4.2 +/- 1.1%), or room air (5.0 +/- 1.8%) alone (p <.05). Rats exposed to hyperoxia + tumor necrosis factor-alpha had significantly higher concentrations of inducible nitric oxide synthase of neutrophils (350.1 +/- 75.7 mean fluorescence intensity), compared with rats with hyperoxia (64.9 +/- 1.6 mean fluorescence intensity), tumor necrosis factor-alpha (102.6 +/- 15.3 mean fluorescence intensity), or room air (111.2 +/- 25.8 mean fluorescence intensity) alone (p <.05). Rats exposed to hyperoxia + tumor necrosis factor-alpha significantly produced higher concentrations of tumor necrosis factor-alpha and interleukin-1 beta, compared with rats with tumor necrosis factor-alpha, hyperoxia, or room air alone. Hyperoxia + tumor necrosis factor-alpha also significantly increased growth-related oncogene/cytokine-induced neutrophil chemoattractant (GRO/CINC)-1 in bronchoalveolar fluid, compared with those receiving tumor necrosis factor-alpha alone, hyperoxia alone, or room air alone. L-NAME significantly enhanced the percentage of neutrophil recovery and the production of tumor necrosis factor-alpha, interleukin-1 beta, and GRO/CINC-1 in airways compared with the corresponding hyperoxia + tumor necrosis factor-alpha treatment alone.


CONCLUSIONS
Endogenous nitric oxide may be an important endogenous inhibitor of hyperoxia + tumor necrosis factor-alpha-induced leukocyte recruitment and subsequently tumor necrosis factor-alpha, interleukin-1 beta, and GRO/CINC-1 release.
Lin
Horng-Chyuan
HC
Department of Thoracic Medicine II, Chang Gung Memorial Hospital, Taipei, Taiwan.
Wang
Chun-Hua
CH
Yu
Chih-Teng
CT
Huang
Kuo-Shiung
KS
Liu
Chien-Ying
CY
Yang
Chih-Wei
CW
Kuo
Han-Pin
HP
D000818:Animals; D016207:Cytokines / Q000378:metabolism*; D018496:Hyperoxia / Q000276:immunology*; D008297:Male; D009504:Neutrophils / Q000276:immunology*; D009569:Nitric Oxide / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D016207:Cytokines; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide