The effect of histamine-1 and histamine-2 antagonists on airway responses to histamine in the rhesus monkey.

This study used rhesus monkeys with consistent respiratory responses to aerosolized histamine. Two systems of histamine challenge were evolved to study the effects of histamine antagonists on the histamine-induced respiratory response. One system consisted of administering increasing subreactive concentrations of histamine until an airway response (H) occurred. This threshold histamine dose was repeated (H'). The pulmonary function changes occurring with the H' challenge were less intense than those with H. M, a histamine-2 receptor antagonist, when given before the H' dose was associated with a potentiated H' response compared with the threshold H response. This provides evidence for histamine-2 receptor sites in rhesus monkey airways. A second system used duplicate histamine challenges with a known reactive dose of histamine. In this system, the pulmonary function changes occurring with the repeated challenge (H') were greater than with the first reactive challenge dose (H). This H' response was inhibited partially with diphenhydramine, a histamine-1 receptor antagonist. These two systems of histamine challenge provide an experimental model for evaluating pharmacologic alteration of histamine-induced respiratory responses. There is evidence for the existence of histamine-1 and histamine-2 receptor sites in the airways of the rhesus monkey.