Neuropeptide Y modulates non-adrenergic, non-cholinergic neural bronchoconstriction in vivo and in vitro.
Non-adrenergic, non-cholinergic (NANC) neural mechanisms regulate airway tone in guinea-pigs, and it is possible that they may be regulated by other nerves. We have investigated effects of neuropeptide Y (NPY), a co-transmitter of adrenergic nerves, on the excitatory (bronchoconstrictor) NANC (e-NANC) response elicited both in vivo (via bilateral vagal nerve stimulation) and in vitro (via electrical field stimulation [EFS]), and on inhibitory (bronchodilator) NANC (i-NANC) responses in upper trachea elicited by EFS. NPY inhibited the e-NANC to vagal stimulation in vivo in a dose-dependent manner (90.0 +/- 3.4% inhibition at 500 micrograms/kg), but failed to alter the bronchoconstrictor response to exogenous substance P (SP). NPY also inhibited the e-NANC response to EFS in main and hilar bronchi (57.2 +/- 8.6% in main and 46.34 +/- 7.5% in hilar bronchi at 10(-6) M), whilst having no effect on the contractile response to SP. In contrast NPY had no effect on the i-NANC response in vitro. Thus, NPY exerts a powerful inhibitory action on tachykinin release from peripheral endings of capsaicin-sensitive airway sensory nerves, but has no effect on the i-NANC neural mechanisms. This suggests that adrenergic nerves may modulate e-NANC responses in the airways.
Stretton
C D
CD
Department of Thoracic Medicine, National Heart and Lung Institute, London, UK.
Belvisi
M G
MG
Barnes
P J
PJ
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001980:Bronchi / Q000294:innervation*; D016084:Bronchoconstriction / Q000502:physiology*; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology; D009478:Neuropeptide Y / Q000502:physiology*; D013373:Substance P / Q000502:physiology; D015320:Tachykinins / Q000378:metabolism; D014132:Trachea / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000502:physiology
D009478:Neuropeptide Y; D015320:Tachykinins; D013373:Substance P; D014660:Vasoactive Intestinal Peptide