Tracheal phenol red secretion, a new method for screening mucosecretolytic compounds.

A simple method for screening drugs that influence tracheobronchial secretion has been described. After i.p. application of a phenol red solution, part of the dye is secreted into the tracheal lumen. This basal secretion is increased by both parasympathomimetics and sympathomimetics. In addition, expectorants are also capable of increasing tracheal phenol red output. Therefore this method is suitable for the study of drugs that may be capable of influencing tracheobronchial secretion.