Central and local cholinergic components of histamine-induced bronchoconstriction in dogs.
To determine the importance of central and local reflexes in the bronchoconstriction produced by inhaled aerosolized histamine, chloralose-urethan-anesthetized dogs were intubated with a double-lumen catheter, ventilated with a dual cylinder respirator, and instrumented for the measurements of pulmonary conductance (GL) and dynamic compliance (Cdyn) in each lung. In each dog, dose-response curves to inhaled aerosolized histamine were obtained in both lungs separately but synchronously. Four series of experiments were performed. In the first series (n = 10) the responses of the right and left lungs were compared and found to be approximately equal, indicating that one lung could be used as a control for the other. In the second and third series the dose-response curve of one lung that had either been treated with inhaled atropine sulfate (n = 6) (4 mg/ml) or vagotomized (n = 4) was compared with the contralateral control lung. At low concentrations of histamine, GL and Cdyn decreased more in the control lungs than in their atropine-treated or vagotomized counterparts, and approximately 40% of the bronchoconstriction induced was reflex in origin. At higher concentrations of histamine the responses of the control and atropine-treated or vagotomized lungs were not significantly different. In the fourth series of experiments (n = 6) histamine dose-response curves were obtained following combined bilateral vagotomy and unilateral delivery of inhaled aerosolized atropine. In these dogs GL, but not Cdyn, fell to a greater extent in the control than in the atropine-treated lung.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001986:Bronchial Spasm / Q000139:chemically induced* / Q000503:physiopathology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006632:Histamine / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects / Q000294:innervation*; D008170:Lung Compliance; D008297:Male; D016210:Methacholine Chloride; D008688:Methacholine Compounds / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology
D008688:Methacholine Compounds; D016210:Methacholine Chloride; D001285:Atropine; D006632:Histamine