Effects of SRS (slow reacting substance) on cyclic nucleotides in guinea pig tracheal muscle.

Leukotriene (SRS) appears to contribute to the prolonged phase of the tracheal contraction induced by egg albumin, indomethacin and tartrazine as this response was effectively antagonised by FPL 55712. Egg albumin, indomethacin and tartrazine reduced the cAMP level of guinea pig trachea pretreated with adrenergic, cholinergic, histaminergic and 5-hydroxytryptaminergic antagonists. Egg albumin, but not the other agents, caused a transient increase of the cGMP content. The metabolic and contractile effects were blocked by FPL 55712. It is suggested that the cAMP reduction caused by egg albumin, indomethacin and tartrazine might promote contractions ot the tracheal muscle.