Abstract
Vagal effects on steady-state resistance of pathways within a segment of lung (Rss) were studied in open-chest dogs using a wedged catheter technique. To prevent adrenergic bronchodilation, dogs were pretreated with propranolol. Rss was determined with vagi intact or sectioned and during electrical stimulation of right and left vagi. Following determination of Rss, gas flow into the segment was arrested, segmental pressure decay recorded, and the time for 90% decay (T90) measured. Stimulation of the vagus supplying the lung with the wedged catheter (ipsilateral) increased Rss and T90 at low (2-4 cmH2O) transpulmonary pressures (Pao) and T90 at high (5-9 cmH2O) Pao. Vagal sectioning and contralateral stimulation had minimal effects. Atropine abolished vagal effects. We modeled the segment as two series compartments, one with a rapid time constant and one with a longer time constant. At both low and high Pao, vagal stimulation prolonged the slow time constant. If the fast compartment represents small airways and the slow compartment collateral pathways, collaterals may not be effective in maintaining ventilation to lung segments distal to a vagally constricted bronchus.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of applied physiology: respiratory, environmental and exercise physiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
