Document Detail

Effects of graded exercise on bronchial blood flow and airway dimensions in sheep.
MedLine Citation:
PMID:  16750924     Owner:  NLM     Status:  MEDLINE    
Exercise stimulus-response relationships for airway blood supply and dimensions have not been described in mammalian species. These relationships are vital for postulates concerning integrated reflex factors normally controlling the airways and which may underlie the asthma syndromes of exercise. This study defines airways stimulus-response relationships in exercising sheep. Ewes between 35 and 40kg were instrumented at left thoracotomy under thiopentone/isoflurane general anaesthesia. Pulsed Doppler ultrasonic transducers were mounted on the bronchial artery, and transit-time plus single-crystal sonomicrometers on the left main bronchus. These recorded simultaneously and continuously bronchial blood flow (Q(br)) and conductance (C(br)), bronchial circumference (Circ(br)) and wall thickness (Th(br)). In Protocol 1 (P1), four sheep ran duplicate 5min protocols on a horizontal treadmill at continuous step-up-and-down speeds of 1min duration, namely, 0.8, 1.6, 2.2, 1.6 and 0.8mph (moderate exercise), followed by 10min recovery. In P2, four sheep ran duplicate 2min protocols at constant 4mph (strenuous exercise), and in P3, one sheep ran duplicate protocols each of 3min at 2.2, 4.4 and 6mph (severe exercise). Regression analysis and repeated measures ANOVA were used to assess differences between times, runs and exercise intensity. In P1, airway effects were directly related to graded exercise effort sustained over 5min. Peak effects occurred at 2.2mph, except for Th(br). Heart rate and P(a) rose (to 156% and 111% of resting, respectively), and Q(br) and C(br) fell (to 83% and 75%; both P<0.001). Circ(br) fell to 96% (P=0.02), and Th(br) rose at low speeds early and late, and thinned at the highest speed. In P2 and P3 for all variables the steady-state effects were systematically greater than for P1 (4.4mph: C(br) to 43%, Circ(br) to 93%; 6.6mph: C(br) to 25%, Circ(br) to 82%). There was no significant recovery hyperaemia, but there was residual post-exercise bronchoconstriction. The exercise stimulus-response relationships from rest to a maximal 6mph for sheep airway circumference and its bronchial circulation are inverse and functionally constrictor.
R Bishop; D McLeod; S McIlveen; R Blake; R Gunther; J Davis; L Talken; D Cottee; A Quail; G Parsons; S White
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-04-21
Journal Detail:
Title:  Pulmonary pharmacology & therapeutics     Volume:  20     ISSN:  1094-5539     ISO Abbreviation:  Pulm Pharmacol Ther     Publication Date:  2007  
Date Detail:
Created Date:  2006-11-27     Completed Date:  2007-07-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9715279     Medline TA:  Pulm Pharmacol Ther     Country:  England    
Other Details:
Languages:  eng     Pagination:  178-89     Citation Subset:  IM    
Discipline of Human Physiology, University of Newcastle, The Hunter Heart-Lung Research Guild, Hunter Medical Research Institute, Callagham, 2308 NSW Australia.
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MeSH Terms
Aorta / drug effects,  physiology
Atrial Function, Right / drug effects
Blood Pressure / drug effects
Bronchi / anatomy & histology,  blood supply*,  drug effects
Bronchoconstriction / drug effects
Heart Rate / drug effects
N-Methylscopolamine / pharmacology
Parasympatholytics / pharmacology
Physical Conditioning, Animal / methods,  physiology*
Pulmonary Circulation / drug effects,  physiology*
Regional Blood Flow / drug effects
Time Factors
Reg. No./Substance:
0/Parasympatholytics; 13265-10-6/N-Methylscopolamine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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