To study effects of cigarette smoke on the cytoplasmic motility (CM) of alveolar macrophages (AM), we measured remanent field strength (RFS) in guinea pigs with and without systemic capsaicin pretreatment in vivo. Four days after instillation of 3 mg/kg ferrimagnetic particles (Fe3O4) into the trachea, RFS was measured at the body surface immediately after magnetization of the Fe3O4 particles by an externally applied magnetic field. RFS decreased with time because of particle rotation (relaxation), which is thought to be correlated to CM of AM. The initial relaxation curve was fitted to an exponential function. The relaxation rate (λ0) increased during cigarette smoke inhalation and returned to baseline values within 5 min, and with the inhalation of the smoke of as many as three cigarettes, peak λ0 increased in animals without capsaicin pretreatment. However, cigarette smoke decreased λ0 with an increased number of cigarettes in animals with capsaicin pretreatment. Injection of nicotine or acetylcholine increased respiratory resistance to a degree similar to that observed with cigarette smoke, but it did not change λ0. However, substance P (SP) increased λ0, and repeated administration of SP produced a significant tachyphylaxis in animals with and without capsaicin pretreatment in a fashion similar to that noted with cigarette smoke inhalation. Acrolein decreased λ0 in animals with and without capsaicin. Colchicine inhibited the cigarette smoke-induced increase in λ0. The content of SP-like immunoreactivity (SP-LI) in guinea pig lung homogenate was 3.6 ± 0.6 pmol/g wet lung, but SP-LI was virtually undetectable in tissues from capsaicin-pretreated guinea pigs. These results strongly suggest that cigarette smoke increases CM of AM through the release of tachykinins from capsaicin-sensitive sensory nerves.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine