[Pharmacological studies on the cough reflex]

Area of Science:

• Pharmacology
• Respiratory Physiology
• Experimental Medicine

Background:

• The cough reflex is a vital protective mechanism.
• Developing reliable animal models for studying cough and antitussives is crucial.
• Existing methods for inducing cough-like reflexes (CLR) in animals may not accurately represent human cough physiology.

Purpose of the Study:

• To compare the characteristics of cough induced by electrical stimulation versus DMPP.
• To investigate the physiological mechanisms underlying DMPP-induced CLR.
• To assess the potential of DMPP-induced CLR as a model for cough research.

Main Methods:

• Induction of cough reflexes in anesthetized dogs and cats using electrical stimulation of the tracheal mucosa and DMPP.
• Dose-response studies and assessment of tachyphylaxis with DMPP.
• Measurement of airway resistance changes.
• Evaluation of the effects of various drugs (opioids, hexamethonium) on DMPP-induced CLR.

Main Results:

• Electrical stimulation of the tracheal mucosa produced a cough curve similar to human coughs.
• DMPP induced a dose-dependent CLR in dogs and cats without tachyphylaxis or effect on airway resistance.
• DMPP-induced CLR was inhibited by opioids and hexamethonium, suggesting a distinct mechanism from the natural cough reflex.

Conclusions:

• Electrical stimulation of the tracheal mucosa provides a more accurate animal model for human cough than DMPP.
• The mechanism of DMPP-induced CLR differs from the physiological cough reflex.
• DMPP-induced CLR may still be valuable for investigating cough physiology and antitussive drug actions.