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Cholinergic responses in different sections of rat airways
Acta Physiologica Scandinavica
|October 1, 1981
Summary
Rat airway smooth muscles show varying sensitivity to cholinergic agonists. Extrapulmonary airways like the trachea and bronchus are more sensitive than intrapulmonary airways, suggesting differences in receptor distribution.
Area of Science:
- Pharmacology
- Respiratory Physiology
Background:
- Cholinergic agonists play a crucial role in regulating airway smooth muscle tone.
- Understanding regional differences in airway smooth muscle sensitivity is vital for respiratory research.
Purpose of the Study:
- To investigate the differential effects of cholinergic agonists on various rat airway preparations.
- To compare the sensitivity of extrapulmonary and intrapulmonary airways to acetylcholine and carbacholine.
Main Methods:
- Isometric contractile responses were measured in four rat airway preparations: trachea, bronchus, bronchiole, and parenchymal strip.
- Dose-dependent responses to acetylcholine (ACh) and carbacholine (CCh) were determined.
- Sensitivity was quantified using pD2-values.
Main Results:
- Significant differences in sensitivity to ACh and CCh were observed between extrapulmonary (trachea, bronchus) and intrapulmonary (bronchiole, parenchymal strip) airways.
- Trachea and bronchus were 10–100 times more sensitive than bronchiole and parenchymal strip.
- Bronchus demonstrated higher sensitivity to ACh than the trachea, potentially due to lower cholinesterase activity.
Conclusions:
- Rat airway smooth muscles exhibit regional variations in cholinergic agonist sensitivity.
- Higher sensitivity in extrapulmonary airways suggests a greater density of cholinergic receptors compared to intrapulmonary airways.