| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Divisions of Pulmonary and Critical Care Medicine and of Physiology, The Johns Hopkins University, Baltimore, Maryland 21224
To determine whether methacholine causes vagally mediated reflex constriction of airway smooth muscle, we administered methacholine to sheep either via the bronchial artery or as an aerosol via tracheostomy into the lower airways. We then measured the contraction of an isolated, in situ segment of trachealis smooth muscle and determined the effect of vagotomy on the trachealis response. Administering methacholine to the subcarinal airways via the bronchial artery (0.5-10.0 µg/ml) caused dose-dependent bronchoconstriction and contraction of the tracheal segment. At the highest methacholine concentration delivered, trachealis smooth muscle tension increased an average of 186% over baseline. Aerosolized methacholine (5-7 breaths of 100 mg/ml) increased trachealis tension by 58% and airways resistance by 183%. As the bronchial circulation in the sheep does not supply the trachea, we postulated that the trachealis contraction was caused by a reflex response to methacholine in the lower airways. Bilateral vagotomy essentially eliminated the trachealis response and the airways resistance change after lower airways challenge (either via the bronchial artery or via aerosol) with methacholine. We conclude that 1) methacholine causes a substantial reflex contraction of airway smooth muscle and 2) the assumption may not be valid that a response to methacholine in humans or experimental animals represents solely the direct effect on smooth muscle.
vagus nerves; trachealis muscle; sheep; asthma
This article has been cited by other articles:
|
|
 |
|
  N. G. Verbout, J. K. Lorton, D. B. Jacoby, and A. D. Fryer Atropine pretreatment enhances airway hyperreactivity in antigen-challenged guinea pigs through an eosinophil-dependent mechanism Am J Physiol Lung Cell Mol Physiol, May 1, 2007; 292(5): L1126 - L1135. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. W. Card, J. W. Voltz, C. D. Ferguson, M. A. Carey, L. M. DeGraff, S. D. Peddada, D. L. Morgan, and D. C. Zeldin Male sex hormones promote vagally mediated reflex airway responsiveness to cholinergic stimulation Am J Physiol Lung Cell Mol Physiol, April 1, 2007; 292(4): L908 - L914. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. Carey, J. W. Card, J. A. Bradbury, M. P. Moorman, N. Haykal-Coates, S. H. Gavett, J. P. Graves, V. R. Walker, G. P. Flake, J. W. Voltz, et al. Spontaneous Airway Hyperresponsiveness in Estrogen Receptor-{alpha}-deficient Mice Am. J. Respir. Crit. Care Med., January 15, 2007; 175(2): 126 - 135. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. J. Canning Reflex regulation of airway smooth muscle tone J Appl Physiol, September 1, 2006; 101(3): 971 - 985. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Koetzler, M. Saifeddine, Z. Yu, F.S. Schurch, M. D. Hollenberg, and F. H. Y. Green Surfactant as an Airway Smooth Muscle Relaxant Am. J. Respir. Cell Mol. Biol., May 1, 2006; 34(5): 609 - 615. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J W Dickinson, G P Whyte, A K McConnell, A M Nevill, and M G Harries Mid-expiratory flow versus FEV1 measurements in the diagnosis of exercise induced asthma in elite athletes Thorax, February 1, 2006; 61(2): 111 - 114. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. L. Yost, G. J. Gleich, D. B. Jacoby, and A. D. Fryer The changing role of eosinophils in long-term hyperreactivity following a single ozone exposure Am J Physiol Lung Cell Mol Physiol, October 1, 2005; 289(4): L627 - L635. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. J. Lein and A. D. Fryer Organophosphorus Insecticides Induce Airway Hyperreactivity by Decreasing Neuronal M2 Muscarinic Receptor Function Independent of Acetylcholinesterase Inhibition Toxicol. Sci., January 1, 2005; 83(1): 166 - 176. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Adler, G. Cieslewicz, and C. G. Irvin Unrestrained plethysmography is an unreliable measure of airway responsiveness in BALB/c and C57BL/6 mice J Appl Physiol, July 1, 2004; 97(1): 286 - 292. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. EVANS, D. B. JACOBY, and A. D. FRYER Effects of Dexamethasone on Antigen-Induced Airway Eosinophilia and M2 Receptor Dysfunction Am. J. Respir. Crit. Care Med., May 1, 2001; 163(6): 1484 - 1492. [Abstract] [Full Text]
|
|
|
|
|
|
E. M. Wagner and W. M. Foster Interdependence of bronchial circulation and clearance of 99mTc-DTPA from the airway surface J Appl Physiol, April 1, 2001; 90(4): 1275 - 1281. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. Evans, K. E. Belmonte, R. W. Costello, D. B. Jacoby, G. J. Gleich, and A. D. Fryer Substance P-induced airway hyperreactivity is mediated by neuronal M2 receptor dysfunction Am J Physiol Lung Cell Mol Physiol, September 1, 2000; 279(3): L477 - L486. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. M. Wagner TNF-alpha induced bronchial vasoconstriction Am J Physiol Heart Circ Physiol, September 1, 2000; 279(3): H946 - H951. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
