ON THE EXPECTORANT ACTION OF PARASYMPATHOMIMETIC DRUGS

¹ Department of Pharmacology, Queen's University, Kingston, Canada

Approximately 400 animals, including albino rats, guinea-pigs, rabbits, cats and dogs, were arranged for the collection of respiratory tract fluid (R.T.F.). A range of (loses of eleven parasympathomimetic drugs (acetylcholine, mecholyl, carbachol, urecholine, furmethide, physostigmine, prostigmine, the dimethylurethane of m-isopropyl-p-dimethyl-amino-phenol methiodide, the dimethylurethane of p-dimethylamino thymol methiodide, pilocarpine and arecoline) was administered subcutaneously.

Practically all the drugs increased the volume output. of R.T.F., some to over 1,000 per cent.

Atropine sulphate eliminated this effect when produced by pilocarpine, selected as an example of this group.

Section of the cervical vagus nerve had no effect upon the action of pilocarpine in cats.

Pilocarpine was as effective in decerebrate as in urethanized cats.

There was some evidence that pilocarpine is less effective in the winter and spring than in the summer months.

The mean specific gravity of cat R.T.F. was slightly lowered by parasympathomimetic drugs.

The relative viscosity of cat R.T.F. was increased by parasympathomimetic drugs.

The chloride content of R.T.F. was markedly increased by parasympathomimetic drugs.