Limits...
Effects of nitric oxide synthase inhibitor omega-nitro-L-arginine methyl ester, on silica-induced inflammatory reaction and apoptosis.

Wang H, Leigh J - Part Fibre Toxicol (2006)

Bottom Line: There were no significant differences in these indices between silica-instilled groups with and without L-NAME injection (p > 0.05) except LDH level.The results also showed that apoptotic leucocytes were identified in BALF cells of silica-instilled groups whereas no significant difference was found between silica-instilled groups with and without L-NAME injection in the apoptotic reaction (p > 0.05).Silica instillation significantly increased the level of BALF nitrite/nitrate and L-NAME injection reduced this increase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Discipline of Public Health, University of Adelaide, 10 Pulteney Street, Adelaide, 5005 SA, Australia. he.wang@adelaide.edu.au

ABSTRACT

Background: Although nitric oxide is overproduced by macrophages and neutrophils after exposure to silica, its role in silica-induced inflammatory reaction and apoptosis needs further clarification. In this study, rats were intratracheally instilled with either silica suspension or saline to examine inflammatory reactions and intraperitoneally injected with omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthases, or saline to examine the possible role of nitric oxide production in the reaction.

Results: Results showed that silica instillation induced a strong inflammatory reaction indicated by increased total cell number, number of neutrophils, protein concentration and lactate dehydrogenase (LDH) activity in bronchoalveolar lavage fluid (BALF). There were no significant differences in these indices between silica-instilled groups with and without L-NAME injection (p > 0.05) except LDH level. The results also showed that apoptotic leucocytes were identified in BALF cells of silica-instilled groups whereas no significant difference was found between silica-instilled groups with and without L-NAME injection in the apoptotic reaction (p > 0.05). Silica instillation significantly increased the level of BALF nitrite/nitrate and L-NAME injection reduced this increase.

Conclusion: Intratracheal instillation of silica caused an obvious inflammatory reaction and leucocyte apoptosis, but these reactions were not influenced by intraperitoneal injection of L-NAME and reduced production of NO. This supports the possibility that silica-induced lung inflammation and BALF cell apoptosis are via NO-independent mechanisms.

No MeSH data available.


Related in: MedlinePlus

(a) Concentration of NO2-/NO3- (μM) in BALF of rats 2 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control groups. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group. (b) Concentration of NO2-/NO3- (μM) in BALF of rats 4 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control group. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1636655&req=5

Figure 10: (a) Concentration of NO2-/NO3- (μM) in BALF of rats 2 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control groups. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group. (b) Concentration of NO2-/NO3- (μM) in BALF of rats 4 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control group. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group.

Mentions: Nitrite/nitrate can be detected in BALF from all the experimental animals. Silica instillation increased the level of nitrite/nitrate in BALF significantly two and four weeks after instillation and L-NAME injection reduced the increase by about 40% at two weeks time point and 55% at four weeks time point (Figure 10).


Effects of nitric oxide synthase inhibitor omega-nitro-L-arginine methyl ester, on silica-induced inflammatory reaction and apoptosis.

Wang H, Leigh J - Part Fibre Toxicol (2006)

(a) Concentration of NO2-/NO3- (μM) in BALF of rats 2 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control groups. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group. (b) Concentration of NO2-/NO3- (μM) in BALF of rats 4 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control group. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1636655&req=5

Figure 10: (a) Concentration of NO2-/NO3- (μM) in BALF of rats 2 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control groups. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group. (b) Concentration of NO2-/NO3- (μM) in BALF of rats 4 weeks after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME) (mean + se). ** There is a statistically significant difference in comparison with control group. * There is a statistically significant difference in comparison with instillation of silica and injection of saline group.
Mentions: Nitrite/nitrate can be detected in BALF from all the experimental animals. Silica instillation increased the level of nitrite/nitrate in BALF significantly two and four weeks after instillation and L-NAME injection reduced the increase by about 40% at two weeks time point and 55% at four weeks time point (Figure 10).

Bottom Line: There were no significant differences in these indices between silica-instilled groups with and without L-NAME injection (p > 0.05) except LDH level.The results also showed that apoptotic leucocytes were identified in BALF cells of silica-instilled groups whereas no significant difference was found between silica-instilled groups with and without L-NAME injection in the apoptotic reaction (p > 0.05).Silica instillation significantly increased the level of BALF nitrite/nitrate and L-NAME injection reduced this increase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Discipline of Public Health, University of Adelaide, 10 Pulteney Street, Adelaide, 5005 SA, Australia. he.wang@adelaide.edu.au

ABSTRACT

Background: Although nitric oxide is overproduced by macrophages and neutrophils after exposure to silica, its role in silica-induced inflammatory reaction and apoptosis needs further clarification. In this study, rats were intratracheally instilled with either silica suspension or saline to examine inflammatory reactions and intraperitoneally injected with omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthases, or saline to examine the possible role of nitric oxide production in the reaction.

Results: Results showed that silica instillation induced a strong inflammatory reaction indicated by increased total cell number, number of neutrophils, protein concentration and lactate dehydrogenase (LDH) activity in bronchoalveolar lavage fluid (BALF). There were no significant differences in these indices between silica-instilled groups with and without L-NAME injection (p > 0.05) except LDH level. The results also showed that apoptotic leucocytes were identified in BALF cells of silica-instilled groups whereas no significant difference was found between silica-instilled groups with and without L-NAME injection in the apoptotic reaction (p > 0.05). Silica instillation significantly increased the level of BALF nitrite/nitrate and L-NAME injection reduced this increase.

Conclusion: Intratracheal instillation of silica caused an obvious inflammatory reaction and leucocyte apoptosis, but these reactions were not influenced by intraperitoneal injection of L-NAME and reduced production of NO. This supports the possibility that silica-induced lung inflammation and BALF cell apoptosis are via NO-independent mechanisms.

No MeSH data available.


Related in: MedlinePlus