Comparison of responses of tracheal twin spirals to bronchoactive agents.

Cumulative concentration-effect relationships of tracheal twin spirals to histamine, carbamylcholine and isoprenaline were determined by an in vitro study. A tracheal spiral was prepared by cutting a guinea pig trachea from the carina to the larynx in a spiral fashion. This tracheal spiral was then bisected longitudinally into two equal halves to produce tracheal twin spirals. The validity of using tracheal twin spirals as paired tissue was examined in this study by comparing their responses to bronchoactive agents. Concentration-effect relationships of the agents tested did not show significant differences between the twin spirals. This method is recommended to minimize animal variations.