H1 receptor activation increased vascular permeability.

<p>The effects of diphenhydramine (Diphe) or cimetidine (Cime), 2-pyridylethylamine (Pyri) on vascular hyperpermeability. (A) Photographs of representative mouse ears. (B) Quantification of Evans blue leakage (n = 4–6). (C) Quantification of ear thickness (n = 4–6). #<i>P</i> < 0.05, as compared with IgE. (D) Quantification of Evans blue leakage after compound 48/80 (C48/80) application (n = 4–6). (E) Quantification of Evans blue leakage after histamine application (n = 4–7). *<i>P</i> < 0.05, compared with vehicle. #<i>P</i> < 0.05, compared with histamine. Data are presented as mean ± SEM.