Plasma histamine and catecholamines during carbachol-induced bronchoconstriction in normal subjects.

To determine (1) whether changes in plasma histamine occurred during provoked bronchospasm and (2) if so, whether such changes could be related to variations in plasma catecholamines, venous plasma histamine and catecholamines were measured during a dose-response carbachol challenge in eight healthy volunteers. A significant rise in plasma histamine was observed, whereas induced bronchoconstriction was small, 80% +/- 4% of initial specific airway conductance. There was no further increase in plasma histamine, whereas induced bronchoconstriction became more marked (70%, 60%, and 50% of specific airway conductance initial value). Plasma catecholamines did not change throughout the study. We conclude that mast cell degranulation occurs during a carbachol challenge, and that the variations in plasma histamine are not related to changes in plasma catecholamines.