HRH2 and kidney disorder: Histamine (via the H2R) mediates inflammation, which is central to renal diseases, reduces renal blood flow and creatinine and urea clearance at high doses, and modifies activated neutrophils, triggering oxidative burst and the release of reactive oxygen species; H2R activation stimulates renin release, promotes cardiac fibrosis and apoptosis, and plays a role in immune response [2,3,4,5].