title: Ischemia potentiates the reflex bronchodilation evoked by static muscular contraction in dogs.
abstract: In eleven anesthetized dogs, we found that static contraction of hindlimb muscles that were freely perfused decreased total lung resistance by 0.7 +/- 0.1 cm H2O.L-1.sec, whereas static contraction of the same muscles rendered ischemic decreased total lung resistance by 1.5 +/- 0.4 cm H2O.L-1.sec (P less than 0.025). In ten other dogs, we found that static contraction of freely perfused hindlimb muscles decreased total lung resistance by 0.9 +/- 0.2 cm H2O.L-1.sec, whereas dynamic contraction of the same freely perfused muscles decreased total lung resistance by 1.1 +/- 0.3 cm H2O.L-1.sec. The difference in the magnitudes of the bronchodilator responses to the two modes of contraction was not significant (P greater than 0.05). We conclude that a mismatch between blood supply and demand in working skeletal muscle increases the reflex bronchodilator response to static contraction. We also conclude that dynamic contraction evokes a reflex bronchodilation equivalent to that evoked by static contraction provided that the tension produced by the two modes of contraction are equal.
authors.affiliation: Department of Internal Medicine, University of California, Davis.
authors.forename: P A
authors.initials: PA
authors.lastname: Padrid
authors.forename: J R
authors.initials: JR
authors.lastname: Haselton
authors.forename: M P
authors.initials: MP
authors.lastname: Kaufman
mesh_terms: D000403:Airway Resistance / Q000502:physiology*; D000818:Animals; D001980:Bronchi / Q000502:physiology*; D004285:Dogs; D006614:Hindlimb; D007511:Ischemia; D008168:Lung / Q000502:physiology*; D009119:Muscle Contraction; D009132:Muscles / Q000098:blood supply*; D005082:Physical Exertion; D012018:Reflex / Q000502:physiology*