USE OF IN VIVO TRACHEA PREPARATION OF GUINEA-PIG TO ASSESS DRUG ACTION ON LUNG

A method for recording the effects of drugs on an isolated in vivo segment of trachea and on lung pressure of a deeply anaesthetized animal is described. Acetylcholine, angiotensin, histamine, 5‐hydroxytryptamine, prostaglandin (PG) F2α and slow‐reacting substance of anaphylaxis, but not bradykinin, caused an increase in tracheal segment pressure and an increase in lung pressure. Bradykinin caused an increase in lung pressure but a fall in tracheal segment pressure. It was concluded that bradykinin acts mainly on the smaller airways and PGF2α mainly on the larger airways. The tracheal segment responded to adrenaline, aminophylline, ephedrine, isoprenaline, papaverine, PGE1 and PGE2. Propranolol reduced or abolished responses to all these bronchodilators except PGE1 and PGE2. 1969 Royal Pharmaceutical Society of Great Britain