GANGLION-BLOCKING AGENTS ENHANCE NEURALLY MEDIATED BRONCHOCONSTRICTION IN THE GUINEA-PIG - POSSIBLE ROLE OF SENSORY NEUROPEPTIDES

The effect of ganglion blockade by hexamethonium bromide (0.1-100 μmol · kg-1) and pentolinium tartrate (0.01-3 μmol · kg-1) on the bronchoconstriction induced by vagal nerve stimulation (15 HZ, 0.2 ms, 3 s, 7-20 V) was evaluated in the anaesthetized guinea-pig. Both ganglion-blocking agents potentiated this response dose dependently. When the neural bronchoconstriction was suppressed by atropine, hexamethonium restored this response dose dependently. Hexamethonium produced inhibitory effects on vagally induced bronchoconstriction in capsaicin-desensitized and in propranolol- or reserpine-pretreated guinea-pigs. Propranolol (0.03-3 μmol · kg-1) produced a marked dose-dependent increase of neural bronchoconstriction (which was markedly reduced, about 10 times) in capsaicin-desensitized animals. Our results show that ganglion-blocking agents potentiate neural bronchoconstriction in the guinea-pig and that sensory neuropeptides may have a role in this effect. Moreover, β-adrenergic modulation of the release of neuropeptides from vagal sensory fibers is suggested. © 1990.