The effects of indoramin on histamine and antigen-induced changes in respiration in guinea-pigs.

Indoramin, a drug which blocks alpha-adrenergic, histamine and serotonin receptors, was tested as a protective agent during challenge with bronchoconstrictor agents in guinea-pigs. In conscious guinea-pigs, the time of onset of respiratory distress during continuous administration of aerosolized solutions of histamine, serotonin or ovalbumin (with animals pre-sensitized to this antigen) was measured using a force-displacement transducer applied to the animal's back. This time interval for each guinea-pig was compared with and without indoramin pre-treatment. Indoramin was administered by intraperitoneal injection or by aerosol treatment. In anaesthetized animals under artificial respiration respiratory distress was induced by intravenous injection of histamine and measured by the Konzett-Rössler technique. Indoramin treatment significantly protected guinea-pigs in both types of experiment from the effects of each challenging agent.