Pituitary adenylate cyclase activating peptide regulates neurally mediated airway responses.
To clarify the protective effects of pituitary adenylate cyclase activating peptide (PACAP) on airway narrowing, we examined the effects of PACAP on smooth muscle contraction and plasma extravasation in guinea-pig airways. Smooth muscle contraction evoked by electrical field stimulation (EFS) or exogenously applied acetylcholine (ACh) or substance P (SP) was measured before and after PACAP in vitro. The effect of PACAP on airway plasma extravasation was also measured in vivo. In trachea, PACAP (10(-9) - 10(-7) M) significantly suppressed smooth muscle contraction evoked by EFS without affecting ACh sensitivity, suggesting that PACAP inhibits cholinergic neuroeffector transmission. In the main bronchi, PACAP (10(-9) - 10(-8) M) significantly suppressed the contraction evoked by EFS without affecting SP sensitivity in the presence of atropine, suggesting that PACAP inhibits SP release from excitatory nonadrenergic noncholinergic (eNANC) nerves. In animals treated with atropine and propranolol, PACAP attenuated the increase in plasma extravasation induced by electrical vagus stimulation or by SP. These results suggest that pituitary adenylate cyclase activating peptide may play a role in modulation of airway responses through inhibition of cholinergic and noncholinergic mechanisms.
Shigyo
M
M
Research Institute for Diseases of the Chest, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Aizawa
H
H
Inoue
H
H
Matsumoto
K
K
Takata
S
S
Hara
N
N
D000109:Acetylcholine / Q000494:pharmacology; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects / Q000502:physiology; D046508:Culture Techniques; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009130:Muscle, Smooth / Q000098:blood supply / Q000294:innervation / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009479:Neuropeptides / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology*; D013373:Substance P / Q000494:pharmacology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D013373:Substance P; D000109:Acetylcholine