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Cationic proteins alter smooth muscle function by an epithelium-dependent mechanism
A J Coyle1, W Mitzner, C G Irvin
1Department of Medicine, University of Colorado Health Science Center, Denver.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1993
Summary
Synthetic cationic proteins, poly-L-arginine and poly-L-lysine, alter airway responses by interacting with the respiratory epithelium. These proteins modify epithelium-dependent reactions without causing apparent cell damage, suggesting a charge-mediated mechanism.
Area of Science:
- Respiratory Physiology
- Pharmacology
- Epithelial Biology
Background:
- Airway smooth muscle responses are influenced by the respiratory epithelium.
- The selective permeability of the airway epithelium affects agonist potency.
Purpose of the Study:
- To investigate the effect of synthetic cationic proteins on epithelium-dependent airway responses.
- To determine if poly-L-arginine and poly-L-lysine modify methacholine and KCl responses in guinea pig trachea.
Main Methods:
- Utilized a perfused guinea pig tracheal tube preparation for selective agonist application.
- Chemically removed the epithelium using CHAPS to assess epithelium-dependent responses.
- Applied cationic proteins (poly-L-arginine, poly-L-lysine) and polyanions (poly-L-aspartate) to the luminal or serosal surfaces.
Main Results:
- Intraluminal application of cationic proteins increased methacholine potency and attenuated KCl-induced relaxation.
- Epithelium removal abolished these epithelium-dependent responses.
- Effects were observed without overt epithelial cell damage and were inhibited by polyanions.
- Serosal application of cationic proteins or intraluminal polyanions had no significant effect.
Conclusions:
- Cationic proteins can modify epithelium-dependent airway smooth muscle responses.
- A charge-mediated interaction with the respiratory epithelium is suggested.
- These interactions may lead to airway smooth muscle dysfunction.