Neurotransmitter systems in mouse airways

Peter W ABEL,Cameron M KIEFFER,Ya-ping TU

(Department of Pharmacology,Creighton University School of Medicine,Omaha,NE 68178,USA)

T3-3

Neurotransmitter systems in mouse airways

Peter W ABEL,Cameron M KIEFFER,Ya-ping TU

(Department of Pharmacology,Creighton University School of Medicine,Omaha,NE 68178,USA)

OBJECTIVEThe objective of this study was to characterize the neurotransmitter systems that cause constriction of murine airways.METHODSMurine precision cut lung slices(PCLS)and trachea were prepared,placed into perfusion chambers equipped with platinum electrodes and stimulated transmurally(1.0 ms,50 V,0.1-30 Hz).To measure PCLS constriction,changes in airway luminal area in response to electric field stimulation(EFS)were captured as video images quantified using Image J software.For trachea,changes in isometric tension were recorded using Grass force transducers.Frequency response curves were generated in the absence and the presence of the inhibitors magnesium,atropine and capsaicin and responses analyzed and compared using a student′s t-test(P＜0.05).RESULTSEFS caused airway constriction in a frequency-dependent manner that was best fit by a biphasic curve.Neuron-specific stimulation was verified by Mg2+blockade.Maximum airway constriction to 30 Hz EFS in PCLS was(51.8±3.0)%while tracheal constriction averaged(551±80)mg.Interestingly,in PCLS the muscarinic receptor antagonist atropine(10 μmol· L-1)blocked(99.5 ± 7.2)%of EFS induced constriction at 1 Hz,but only blocked(23.3±3.8)%of EFS induced constriction at 30 Hz and eliminated the first phase but not the second phase of the biphasic EFS response.Treatment with capsaicin to deplete sensory neurotransmitters significantly increased EFS constriction supporting the presence of sensory neurotransmitter systems in airways.CONCLUSIONThese data are consistent with parasympathetic constriction of airways by acetylcholine at lower EFS frequencies while higher frequencies release sensory dilator neurotransmitters.These data provide evidence for multiple nerve types innervating airways which may provide novel targets for treatment of lung disease.

airways;nerve stimulation;airway constriction;atropine;capsaicin

The project supported by State of Nebraska LB595

Peter W ABEL，Tel:4022802983,E-mail：pabel@creighton.edu