In vitro reactivity (“organ chamber”) of guinea pig tracheal rings—methodology considerations

The present text was motivated by the difficulties faced by our postgraduate students when using airways studies protocols and will take into consideration the three mechanisms of relaxation: (I) guanosine 3,5-cyclic monophosphate (cGMP)/NO-dependent; (II) adenosine 3,5-cyclic monophosphate (cAMP)/PGI2-dependent, and (III) hyperpolarization-dependent. Tracheal rings are studied in an organ bath containing a gassed physiological salt solution, usually at a temperature of 37 ℃. An agent or procedure that causes contraction [acetylcholine (Ach) or metacholine] of the smooth muscle is needed before study airway dilator drugs. The presented airways studies protocols are useful to study the bronchial epithelial-dependent reactivity.