Substance P fails to mimic vagally mediated nonadrenergic bronchodilation.
The ability of substance P to mimic vagally mediated nonadrenergic bronchodilation was assessed in vivo in anesthetized, paralyzed, artificially ventilated cats. Infusion of the peptide at a rate of 10 micrograms kg-1 min-1 for 10 minutes did not attenuate the increase in pulmonary resistance evoked by efferent vagal stimulation. Similarly, when administered as an aerosol (1-15 breaths of a 100 micrograms ml-1 aqueous solution) or by bolus intravenous injection, substance P failed to reverse the increase in pulmonary resistance maintained by a continuous intravenous infusion of 5-hydroxytryptamine. These results indicate that substance P is unlikely to be the neurotransmitter responsible for mediating nonadrenergic inhibitory responses in feline airways.
D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D002415:Cats; D004558:Electric Stimulation; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology*; D014630:Vagus Nerve / Q000502:physiology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D012701:Serotonin; D013373:Substance P; D014660:Vasoactive Intestinal Peptide