ABSTRACT
This chapter shows neuropeptides effects on mucus secretion, bronchial blood flow, vascular permeability, and bronchomotor tone, and proposes a neuromodulatory role for neuropeptides. It suggests that tachykinins may have a neuromodulatory role in the peripheral nervous system that was in the guinea pig myenteric plexus where substance P was found to evoke the release of acetylcholine in a concentration-dependent manner. Exogenous tachykinins have been shown previously to facilitate cholinergic neurotransmission in airway smooth muscle. They also potentiate cholinergic neurotransmission at pre- and postganglionic nerve terminals in guinea pig trachea. Sekizawa and colleagues have demonstrated that inhibitors of neutral endopeptidase increase the contractions of ferret trachea evoked by electrical field stimulation (EFS) in vitro. In human bronchial rings none of the selective tachykinin receptor agonists had any effect on cholinergic neurotransmission. Opioids have been shown to inhibit cholinergic neurotransmission, at low frequencies of stimulation, in canine airways via a postganglionic, prejunctional mechanism of action.
