High histamine concentrations are known to mediate the pathological contraction of smooth muscles cells in the bronchiolar walls, including during acute attacks of asthma and anaphylactic reactions mediated by H1R. H1R is coupled to Gαq/11 protein, which cleaves phosphatidylinositol 4,5-bisphosphate to diacylglycerol and inositol 1,4,5-trisphosphate, via the activation of phospholipase C. This results in Ca2+ influx and initiates smooth muscle contraction (3). This evidence concerns the gene HRH1 and asthma.