An in vivo guinea pig preparation for studying the autonomic regulation of airway smooth muscle tone.

The autonomic nervous system plays a primary role in regulating airway smooth muscle tone. Here, we describe the development of an in vivo guinea pig model that permits systematic studies of the autonomic control of airway smooth muscle. The model is based on preparations previously described and utilizes measurements of isometric tension in a perfused segment of extrathoracic guinea pig trachea in situ. It has the advantage that the autonomic innervation to the tracheal segment under study can be physiologically or pharmacologically isolated and studied independently from other mechanisms regulating airway smooth muscle tone. Initial experiments were conducted to optimize model conditions. Subsequent experiments were designed to highlight the usefulness of this preparation for studying parasympathetic regulation of airway caliber. The results of the study demonstrate the utility of this model for future studies into the neural regulation of bronchomotor tone and the mechanisms of airway obstruction and hyperreactivity associated with disease.