Substance P relaxes rat bronchial smooth muscle via epithelial prostanoid synthesis.
BACKGROUND
Substance P is present in bronchial nerve fibres. The physiological actions of substance P are mediated via tachykinin NK(1) receptors. Immunochemical studies have demonstrated tachykinin NK(1) receptors in the rat airway epithelium.


OBJECTIVE
To elucidate how epithelial tachykinin NK(1) receptors affect smooth muscle response to substance P.


METHODS
Contractile response of isolated rat bronchial trunk with or without epithelium was recorded.


RESULTS
In intact segments precontracted by 5-hydroxytryptamine, relaxation was induced by substance P and the nitric oxide donor, sodium nitroprusside. Removal of the epithelium abolished relaxation induced by substance P but did not affect relaxation induced by sodium nitroprusside. The cyclo-oxygenase inhibitor, indomethacin, but not the nitric oxide synthase inhibitor, L-N(G)-monomethylarginine, reduced the relaxation in response to substance P.


CONCLUSIONS
Epithelial tachykinin NK(1) receptors mediate substance-P-induced relaxation of rat bronchial smooth muscle via release of prostanoids but not nitric oxide.
Bodelsson
M
M
Department of Anaesthesia and Intensive Care, University Hospital, Lund, Sweden. Mikael.Bodelsson@anest.lu.se
Blomquist
S
S
Caverius
K
K
Törnebrandt
K
K
D000818:Animals; D001980:Bronchi / Q000187:drug effects* / Q000502:physiology; D004848:Epithelium / Q000378:metabolism; D005260:Female; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009412:Nerve Fibers / Q000187:drug effects; D011453:Prostaglandins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018040:Receptors, Neurokinin-1 / Q000187:drug effects / Q000502:physiology*; D013373:Substance P / Q000494:pharmacology*
D011453:Prostaglandins; D018040:Receptors, Neurokinin-1; D013373:Substance P