Cigarette smoke-induced bronchoconstriction and release of tachykinins in guinea pig lungs

Two series of experiments were carried out to determine whether the release of tachykinins is involved in the bronchoconstriction induced by inhalation of cigarette smoke in guinea pigs. In the first series, cigarette smoke consistently induced bronchoconstriction (ΔRl = + 203% and ΔCdyn = -46%) in anesthetized guinea pigs, and the response was only partially blocked by bilateral cervical vagotomy. However, the smoke-induced bronchial constriction was completely abolished in animals receiving a systemic capsaicin pretreatment to destroy the tachykinin-containing C-fiber afferents. In the second series, the bronchoconstrictive effect of cigarette smoke was increased by approx. three times in isolated perfused guinea pig lungs when phosphoramidon (3 × 10^-6 M) was added to the perfusate to prevent the degradation of tachykinins after their release. Moreover, the enhanced bronchomotor response to smoke was accompanied by an overflow of neurokinin A-like immunoreactivity (LI) and calcitonin gene-related peptide -LI in the pulmonary effluent. These studies showed that cigarette smoke triggers the release of tachykinins in the lungs, which plays an important role in the smoke-induced bronchoconstrictive effect in guinea pigs.