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Vasomotion influences airflow in peripheral airways.
M E Csete1, W M Abraham, A Wanner
1Pulmonary Division, University of Miami, Mount Sinai Medical Center, Miami Beach, Florida 33140.
The American Review of Respiratory Disease
|June 1, 1990
Summary
Blood flow significantly impacts peripheral airway resistance. Vasodilation, induced by nitroglycerin, increased resistance, while bronchoconstriction from carbachol also raised resistance, supporting blood volume
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
- Vascular Biology
Background:
- Peripheral airway resistance is crucial for lung function.
- The influence of blood flow and volume on airway resistance is not fully understood.
Purpose of the Study:
- To investigate the hypothesis that blood flow, via its effect on blood volume, influences airflow resistance in peripheral airways.
- To differentiate the effects of vascular and airway smooth muscle modulation on peripheral airflow resistance.
Main Methods:
- Utilized conscious ewes with a fiberoptic bronchoscope in a segmental bronchus.
- Applied forced sinusoidal flow oscillations to measure peripheral airflow resistance (Rp).
- Administered drugs with vascular (nitroglycerin) or airway smooth muscle (carbachol) effects locally.
Main Results:
- Nitroglycerin (vasodilator) dose-dependently increased Rp, an effect blocked by methylene blue.
- Carbachol (bronchoconstrictor) dose-dependently increased Rp, an effect reversed by atropine.
- Nitroglycerin-induced increases in Rp were reversed by vasopressin, while carbachol-induced increases were reversed by isoproterenol.
Conclusions:
- Nitroglycerin increased peripheral airflow resistance through vasodilation, suggesting vascular congestion.
- Carbachol increased peripheral airflow resistance via bronchoconstriction.
- The findings support the hypothesis that vasodilation and associated changes in blood volume limit airflow in the lung periphery.