Facilitation by tachykinins of neurotransmission in guinea‐pig pulmonary parasympathetic nerves

Abstract

1 The effect of tachykinins on cholinergic neurotransmission was studied in an innervated tracheal tube preparation isolated from guinea-pigs anaeshetized with urethane. These results suggest that tachykinins act on NK2 receptors, both on the trachealis muscle and on postganglionic pulmonary parasympathetic nerve terminals. Activation of the neuronal receptors may increase the probability of transmitter release from the nerve terminals.

Endogenous tachykinins facilitate transmission through parasympathetic ganglia in guinea‐pig trachea

“…These data support the growing evidence from immunohistochemical (Sheppard et al, 1983;Dey et al, 1991), electrophysiological (Cameron & Coburn, 1984;Baker et al, 1986;Myers et al, 1990) and functional (Martling et al, 1984;Hall et al, 1989;Stretton et al, 1992) studies, which suggest that tachykinins may play a facilitatory role in cholinergic control of airway smooth muscle tone.…”

“…Slow e.p.s.ps are often associated with peptidergic neurotransmission (Kuffler, 1980;Hartzel, 1981) and in sympathetic ganglia these slow e.p.s.ps can be evoked by an LHRH-like peptide (Jan et al, 1980;Jan & Jan, 1981). Tachykinins may be the neurotransmitters responsible for these slow e.p.s.ps, since they facilitate parasympathetic neurotransmission as do slow e.p.s.ps (Martling et al, 1984;Sekizawa et al, 1987;Hall et al, 1989;Stretton et al, 1992) and have been identified in nerves closely association with airway ganglia (Dey et al, 1991). Preliminary electrophysiological studies of guinea-pig bronchial ganglia indicate that tachykinins mimic the depolarization induced by capsaicin in these nerve cell bodies (Myers & Undem, 1992).…”

“…Exogenous tachykinins have been shown to facilitate cholinerneuropeptide depletion with capsaicin (Martling et al, 1984) gic neurotransmission in guinea-pig airways via NK2 receptors indicating a facilitatory role of endogenous capsaicin-sensi- (Hall et al, 1989). A component of the bronchoconstrictor trophysiological studies have demonstrated slow excitatory postsynaptic potentials (e.p.s.ps) within airway ganglia (Cameron & Coburn, 1984;Coburn, 1984;Coburn & Kalia, 1986;Burnstock et al, 1987).…”

Modulation of cholinergic neurotransmission in guinea‐pig airways by opioids

“…This suggests that the NANC neurotransmitter (probably a tachykinin) may facilitate cholinergic neurotransmission and that it is this facilitatory effect that is primarily inhibited by opioids. Exogenous tachykinins do indeed facilitate neurotransmission in postganglionic cholinergic nerves in this species (Hall et al, 1989). Furthermore, capsaicin pretreatment, which depletes sensory neurones of SP, reduces the cholinergic response in airways to EFS in vivo (Martling et al, 1984) and also in vitro (Stretton et al, 1989).…”

Facilitatory effects of selective agonists for tachykinin receptors on cholinergic neurotransmission: evidence for species differences

“…In addition, SP potentiates cholinergic nerve-induced contractions in rabbit trachea in vitro via a postganglionic, prejunctional mechanism (Armour et al, 1991). Exogenous tachykinins also potentiate cholinergic neurotransmission in guinea-pig trachea (Hall et al, 1989;Watson et al, 1993).…”