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[Effects of 7-nitroindazole on smoke inhalation pulmonary injury]
Wei Liu1, Fa-Guang Jin, Gui-Sheng Qian
1Department of Respiratory Medicine, Tangdu Hospital, The Fourth Military Medical University, Xi'an, Shanxi, China. liuweilung@163.com
Objective:
To investigate the effects of neuronal nitric oxide synthase (nNOS) inhibitor 7-nitroindazole (7-NI) on smoke inhalation pulmonary injury in rats.
Methods:
Forty healthy male SD rats were randomly divided into three groups: control group (n=8), smoke inhalation model group (n=16) and 7-NI treatment group (n=16). After reproducing the smoke inhalation model, to the 7-NI treatment group rats 7-NI (20 mg/kg in 2 ml arachis oil) was administered by intraperitoneal injection, while in the control group and the model group, 2 ml arachis oil was administered by intraperitoneal injection. Arterial blood gas analysis was monitored at 2, 6, 12 and 24 hours. After rats were sacrificed, lung water was determined. The activities of super oxide dismutase (SOD), catalase (CAT), nitric oxide synthases (NOS), and the contents of tumor necrosis factor-alpha (TNF-alpha), nitric oxide (NO) were determined in pulmonary tissue homogenate. The pathological changes in pulmonary tissue were observed under light microscope.
Results:
Compared with model group, in 7-NI treatment group, arterial partial pressure of oxygen (PaO(2)) was elevated at each time point (all P<0.05), lung water was decreased (P<0.05). The activities of SOD and CAT were enhanced (all P<0.05), and the activities of nNOS and the content of NO were decreased (all P<0.05). TNF-alpha contents in lung tissues were decreased at 2 and 6 hours (both P<0.05). Pathological changes of less inflammatory cells infiltration and no punctate hemorrhage in lung interstitium in 7-NI treatment group than those in model group were seen under light microscope.
Conclusion:
7-NI shows a good protective effect on smoke inhalation pulmonary injury, that it can raise PaO(2), increase the antioxidation ability, ameliorate lung edema and tissue inflammatory cells infiltration.
Insights
Neuronal nitric oxide synthase (nNOS) inhibitor 7-nitroindazole (7-NI) protected rats from smoke inhalation lung injury. This treatment improved oxygen levels, reduced lung water, and decreased inflammation.
Area of Science:
- Pulmonary Medicine
- Toxicology
- Pharmacology
Background:
- Smoke inhalation causes significant pulmonary injury.
- Nitric oxide synthase (NOS) plays a role in inflammatory responses.
- Neuronal nitric oxide synthase (nNOS) is implicated in lung injury.
Purpose of the Study:
- To evaluate the therapeutic potential of the nNOS inhibitor 7-nitroindazole (7-NI) in a rat model of smoke inhalation pulmonary injury.
- To assess the impact of 7-NI on physiological and biochemical markers of lung injury.
Main Methods:
- A smoke inhalation model was established in Sprague-Dawley rats.
- Rats were treated with 7-NI (20 mg/kg) or vehicle via intraperitoneal injection.
- Arterial blood gases, lung water content, antioxidant enzyme activities (SOD, CAT), NOS activity, nitric oxide (NO) levels, and TNF-alpha were measured.
- Pulmonary histopathology was examined.
Main Results:
- 7-NI treatment significantly increased PaO(2) and decreased lung water content compared to the smoke-induced injury group.
- Antioxidant enzyme activities (SOD, CAT) were enhanced, while nNOS activity and NO levels were reduced by 7-NI.
- Tumor necrosis factor-alpha (TNF-alpha) levels were decreased at early time points post-injury.
- Histological examination revealed reduced inflammatory cell infiltration and hemorrhage in the lungs of 7-NI treated rats.
Conclusions:
- 7-NI demonstrates significant protective effects against smoke inhalation-induced pulmonary injury in rats.
- The protective mechanism involves improving oxygenation, enhancing antioxidant capacity, reducing lung edema, and mitigating inflammation.
