Histamine-mediated mechanisms in the human nasal airway

The nasal actions of histamine were originally attributed to vascular and neuronal H(1) receptor activation. Recent studies have identified a H(3) receptor that contributes to histamine-induced inflammation via the inhibition of sympathetic activity. There is also evidence that pollen-induced nasal blockage can be treated by H(1) antagonists. However, although desloratadine might offer relief, this is unlikely to be through inhibition of nasal H(1) receptors. Despite evidence of an active H(2) receptor on nasal vasculature, this receptor subtype appears to play only a minor role in nasal inflammation. The activation of H(1) receptors cannot account for all of the acute actions of histamine in the nasal airway.