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Effect of catecholamines on pulmonary circulation at elevated vascular tone
1Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta 30912, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1995
Summary
Catecholamines affect canine pulmonary vasculature by altering resistance and compliance via alpha and beta receptors. These effects diminish when vascular tone is elevated, impacting lung fluid balance.
Area of Science:
- Pulmonary Circulation Physiology
- Adrenergic Receptor Pharmacology
Background:
- Catecholamines like norepinephrine and epinephrine influence vascular tone.
- Pulmonary vascular resistance and compliance are critical determinants of lung function.
Purpose of the Study:
- To investigate the impact of catecholamine stimulation on pulmonary vascular resistance and compliance.
- To examine how elevated vascular tone modifies catecholamine effects in the canine pulmonary circulation.
Main Methods:
- Isolated dog lung blood perfusion at constant flow.
- Utilized arterial, venous, and double-occlusion techniques to measure segmental resistances and compliances.
- Evaluated responses under control and elevated vascular tone (induced by U-46619).
Main Results:
- Under normal tone, catecholamines increased pulmonary vascular resistance and decreased compliance via alpha and beta receptor stimulation.
- Epinephrine demonstrated a stronger effect on beta 2-receptors than norepinephrine.
- With elevated vascular tone, catecholamine effects on resistance were abolished, and compliance was unaffected.
Conclusions:
- Adrenergic receptor systems modulating pulmonary vascular tone are altered by elevated vascular tone.
- These alterations may influence pulmonary capillary pressure and lung fluid balance.
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