Protease-induced constriction in rats' bronchi

Area of Science:

• Pulmonary Physiology
• Pharmacology

Background:

• Assessing bronchomotor function is crucial for understanding airway diseases.
• Existing methods may have limitations in covering the entire tracheobronchial tree.

Purpose of the Study:

• To develop and apply a novel in vitro method for quantitative measurement of bronchomotor function.
• To investigate the effects of specific proteases on rat airway smooth muscle contraction.
• To elucidate the receptor mechanisms involved in protease-induced airway contraction.

Main Methods:

• Quantitative in vitro measurement of bronchomotor function across the tracheobronchial tree.
• Administration of chymotrypsin, trypsin, and ficin to rat airway segments.
• Assessment of contractile responses in the presence and absence of antagonists like phentolamine and atropine, and with physostigmine.

Main Results:

• Chymotrypsin, trypsin, and ficin induced significant airway contractions in rat intrapulmonary airways.
• Phentolamine and atropine partially or completely abolished these protease-induced contractions.
• Physostigmine did not enhance the observed contractile responses.

Conclusions:

• Chymotrypsin-induced airway contraction is primarily mediated by alpha-adrenoreceptors.
• Trypsin and ficin-induced airway contraction involve both alpha-adrenoreceptors and cholinoceptive receptors.
• The developed method provides a valuable tool for studying airway physiology and pharmacology.