Histamine and the nasal vasculature: the influence of H1 and H2-histamine receptor antagonism.

The aim was to determine the effect of H1- and H2-receptor blockade on histamine-induced changes in nasal airways resistance and lavage protein concentrations. Normal subjects were pretreated with oral cetirizine or ranitidine in a double-blind and randomized manner. Measurements of the concentration of total protein and albumin in nasal lavage fluid together with nasal airway resistance were made before and after challenge. Any effect of treatment was assessed by comparing the areas under the time-response curves. In all nine subjects available for analysis histamine caused an immediate increase in all measurements. Ranitidine reduced the maximum increase in nasal airway resistance, but this effect was significant only in combination with certirizine. The increase in lavage total protein and albumin concentrations was almost completely abolished by cetirizine, whereas ranitidine had less effect. We conclude that the histamine H1-receptor has the greatest effect on changes in nasal vascular permeability induced by topical histamine, whereas the H2-receptor has the greatest effect on nasal obstruction.