Continuous Determination of Tracheobronchial Secretory Activity in Dogs

Abstract

We have designed a new method for continuous recording of the output of respiratory tract fluid, the approach representing a modification and combination of the intratracheal electrode and stopper methods which we had employed originally. Electrical resistance change indicated alteration in the output of respiratory tract fluid, without alteration in composition and temperature of fluid, tracheal muscular tone or respiratory movement, at least, within a physiological range. Among the expectorant drugs thus tested, pilocarpine, 100 and 200 μg/kg given intravenously, significantly and in a dose dependent manner augmented the output of the fluid about 5 minutes after the administration. Given orally in a dose of 2 mg/kg, the output of fluid increased in about 20 minutes. Senega syrup, 0.3 ml/kg had no effect when given intravenously, yet, 2 ml/kg given orally increased the output of fluid within 5 minutes, thereby suggesting that the related secretagogic activity is due to a reflex action following stimulation of the gastric mucosa. Emetine, 2 mg/kg given orally increased the output about 20 minutes after administration while glyceryl guaiacolate, 50 mg/kg had no effect. We propose that our method be used to evaluate expectorants for clinical use as the continuous monitoring of the output of respiratory tract fluid apparently provides a more accurate assessment.