Schoeb T R, Davidson M K, Lindsey J R
Infect Immun. 1982 Oct;38(1):212-7. doi: 10.1128/iai.38.1.212-217.1982.
Ammonia (NH3) from soiled cage bedding is known to enhance the progression and severity of murine respiratory mycoplasmosis in rats. To test the hypothesis that NH3 directly or indirectly enhances the growth of Mycoplasma pulmonis in vivo, pathogen-free F344 rats were inoculated intranasally with 1 x 10(4) to 4 x 10(4) or 4 x 10(6) to 5 x 10(6) colony-forming units of M. pulmonis and exposed to less than or equal to 1.5 or 76 microgram of NH3 per liter (less than or equal to 2 or 100 ppm, respectively). Nasal passages, larynges, tracheas, and lungs from rats killed at intervals up to 28 days after inoculation were quantitatively cultured. Growth of M. pulmonis was much greater in NH3-exposed rats than in controls, particularly in those inoculated with the lower dose. Increases in M. pulmonis populations were more rapid in proximal airways than in distal airways. Serum immunoglobulin G and M antibody responses to M. pulmonis as measured by an enzyme-linked immunosorbent assay were greater in NH3-exposed rats. In other experiments, the nasal passages absorbed virtually all NH3 when the rats were exposed to less than 380 micrograms of NH3 per liter (500 ppm), indicating that NH3 induced increases in the numbers of organisms in the distal respiratory tract, probably by a secondary, rather than a direct, effect. Also, NH3 exposure did not inhibit pulmonary antibacterial activity as measured by clearance of radiolabeled Staphylococcus epidermidis. The growth of M. pulmonis in vitro was inhibited by 1 mM NH4+ added to the medium as NH4OH but not by NH4+ concentrations of 0.5, 0.1, or 0.01 mM, suggesting that NH3 increases growth indirectly through effects on the host.
已知来自脏污笼具垫料的氨（NH₃）会加重大鼠的鼠呼吸道支原体病的进展和严重程度。为了验证NH₃直接或间接促进体内肺支原体生长的假说，将无特定病原体的F344大鼠经鼻接种1×10⁴至4×10⁴或4×10⁶至5×10⁶个肺支原体菌落形成单位，并暴露于每升小于或等于1.5或76微克的NH₃（分别小于或等于2或100 ppm）环境中。对接种后长达28天内不同时间点处死的大鼠的鼻道、喉、气管和肺进行定量培养。暴露于NH₃的大鼠体内肺支原体的生长比对照组要多得多，尤其是那些接种低剂量的大鼠。肺支原体数量在近端气道比远端气道增加得更快。通过酶联免疫吸附测定法测得的暴露于NH₃的大鼠对肺支原体的血清免疫球蛋白G和M抗体反应更强。在其他实验中，当大鼠暴露于每升小于380微克的NH₃（500 ppm）时，鼻道几乎吸收了所有的NH₃，这表明NH₃可能通过间接而非直接作用诱导远端呼吸道中生物体数量增加。此外，通过放射性标记表皮葡萄球菌的清除率来衡量，NH₃暴露并未抑制肺部抗菌活性。在培养基中添加1 mM NH₄⁺（以NH₄OH形式）可抑制体外肺支原体的生长，但0.5、0.1或0.01 mM的NH₄⁺浓度则无此作用，这表明NH₃通过对宿主的影响间接增加生长。
