CIGARETTE SMOKE-INDUCED BRONCHOCONSTRICTION AND RELEASE OF TACHYKININS IN GUINEA-PIG LUNGS

Two series of experiments were carried out to determine whether the re lease of tachykinins is involved in the bronchoconstriction induced by inhalation of cigarette smoke in guinea pigs. In the first series, ci garette smoke consistently induced bronchoconstriction (Delta RL = +20 3% and Delta Cdyn = -46%) in anesthetized guinea pigs, and the respons e was only partially blocked by bilateral cervical vagotomy. However, the smoke-induced bronchial constriction was completely abolished in a nimals receiving a systemic capsaicin pretreatment to destroy the tach ykinin-containing C-fiber afferents. In the second series, the broncho constrictive effect of cigarette smoke was increased by approx. three times in isolated perfused guinea pig lungs when phosphoramidon (3 x 1 0(-6) M) was added to the perfusate to prevent the degradation of tach ykinins after their release. Moreover, the enhanced bronchomotor respo nse to smoke was accompanied by an overflow of neurokinin A-like immun oreactivity (LI) and calcitonin gene-related peptide -LI in the pulmon ary effluent. These studies showed that cigarette smoke triggers the r elease of tachykinins in the lungs, which plays an important role in t he smoke-induced bronchoconstrictive effect in guinea pigs.