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Peptide receptors in the airways
1Department of Pharmacology, Medical School, University of Sherbrooke, Quebec, Canada.
The American Review of Respiratory Disease
|December 1, 1987
Summary
Neurokinins cause guinea pig trachea contraction, while kinins cause relaxation. Both peptides release prostaglandins, which modulate these effects, indicating complex receptor interactions.
Area of Science:
- Pharmacology
- Physiology
Background:
- The isolated guinea pig trachea exhibits opposing peptide effects: neurokinins (like substance P) induce contraction, and kinins (like bradykinin) induce relaxation.
- Both peptide classes stimulate the release of relaxing prostaglandins, which counteract neurokinin-induced contractions and mediate kinin-induced relaxations.
Purpose of the Study:
- To characterize neurokinin receptors in the guinea pig trachea.
- To investigate the mechanism of bradykinin-induced relaxation, specifically exploring B1 and B2 receptor involvement.
Main Methods:
- Comparative analysis of various natural and synthetic peptide agonists on isolated guinea pig trachea.
- Assessment of selective receptor activator effects.
- Evaluation of bradykinin-induced relaxation in the presence of B1 and B2 receptor antagonists.
Main Results:
- The guinea pig trachea possesses receptors for neurokinin A (NKA) and substance P (SP), with NKA > NKB > SP in potency.
- Bradykinin-induced relaxation is independent of B1 and B2 receptors, suggesting an alternative signaling pathway.
- Peptide-induced prostaglandin release plays a significant role in modulating tracheal responses.
Conclusions:
- The isolated guinea pig trachea is a complex system with distinct neurokinin receptor subtypes.
- Bradykinin likely mediates relaxation via a novel receptor or an unknown mechanism, possibly involving prostaglandin release.
- Endogenous prostaglandins significantly influence the overall biological effects of peptides on the trachea.