Bronchoconstriction and apnea induced by cigarette smoke: Nicotine dose dependence

Recently, evidence was presented to suggest that nicotine absorbed from cigarette smoke was the main cause of smoke-induced bronchoconstriction (Hartiala et al., J Appl Physiol (1985) 59(1): 64-71). However, due to the qualitative nature of the data, it remains unclear whether cigarette-smoke-induced bronchoconstriction is related to the nicotine content of the smoke in a dose-dependent manner. Experiments were performed on intact anesthetized dogs (n = 6). Each animal spontaneously inhaled 300 cc smoke containing low (0.37 mg), medium (1.46 mg), or high (1.80 mg) levels of nicotine. Isometric tension was measured in an isolated tracheal segment not exposed to the smoke as an index of bronchoconstriction. In all dogs there was a nicotine dose-dependent increase in tracheal tension. The time in expiration (T_e) in the breath following smoke inhalation was prolonged, the magnitude of prolongation being dependent upon the nicotine content of the smoke. These results suggest that bronchoconstriction and changes in T_e induced by cigarette smoke are nicotine-dependent.