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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

Total cell number in bronchoalveolar lavage fluid of rats after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME). QL = silica (quartz) + L-NAME; QS = silica + saline; SL = saline + L-NAME; SS = saline + saline (These abbreviations also apply to subsequent figures) (mean + se).
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Figure 1: Total cell number in bronchoalveolar lavage fluid of rats after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME). QL = silica (quartz) + L-NAME; QS = silica + saline; SL = saline + L-NAME; SS = saline + saline (These abbreviations also apply to subsequent figures) (mean + se).

Mentions: Intratracheal instillation of silica induced an obvious inflammatory reaction in silica-instilled rats but not in the saline-instilled rats. Intraperitoneal injection (ip) of L-NAME in a dosage of 15 mg/kg/day did not influence the inflammatory reaction significantly. There was no significant difference in total cell number of bronchoalveolar lavage fluid (BALF) between (it) silica + (ip) saline and (it) silica + (ip) L-NAME groups (p > 0.05, Figure 1). Both silica-instilled groups showed larger numbers of total cells than the saline-instilled groups but the difference was not statistically significant possibly due to the large individual variation in silica-instilled groups.


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)

Total cell number in bronchoalveolar lavage fluid of rats after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME). QL = silica (quartz) + L-NAME; QS = silica + saline; SL = saline + L-NAME; SS = saline + saline (These abbreviations also apply to subsequent figures) (mean + se).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Total cell number in bronchoalveolar lavage fluid of rats after intratracheal instillation of silica or saline and intraperitoneal injection of saline or ω-nitro-L-arginine methyl ester (L-NAME). QL = silica (quartz) + L-NAME; QS = silica + saline; SL = saline + L-NAME; SS = saline + saline (These abbreviations also apply to subsequent figures) (mean + se).
Mentions: Intratracheal instillation of silica induced an obvious inflammatory reaction in silica-instilled rats but not in the saline-instilled rats. Intraperitoneal injection (ip) of L-NAME in a dosage of 15 mg/kg/day did not influence the inflammatory reaction significantly. There was no significant difference in total cell number of bronchoalveolar lavage fluid (BALF) between (it) silica + (ip) saline and (it) silica + (ip) L-NAME groups (p > 0.05, Figure 1). Both silica-instilled groups showed larger numbers of total cells than the saline-instilled groups but the difference was not statistically significant possibly due to the large individual variation in silica-instilled groups.

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