Histamine, Mast Cells, and Heart Failure

e have known about histamine receptors in the heart for any years (1). The human H1and H2-histamine recepors were cloned and characterized in the early 1990s (2,3), ollowed closely by the human H3and H4-histamine eceptors several years later (4,5). Histamine is a natural ody constituent that is found throughout the body, espeially the central nervous system, mast cells, gastric mucosa arietal cells, and basophils. The H1-receptor is coupled to -q11 and activates a number of intracellular signals, ncluding cyclic adenosine monophosphate (cAMP) and yclic guanosine monophosphate. In the heart, histamine ecreases atrioventricular node conduction time via H1eceptors. The H2-histamine receptors are also found in the eart, and couple to G s proteins to signal through cAMP o produce chronotropic and inotropic activity. The H2istamine receptors also subserve hypotension, flushing, eadache, increased gastric acid production, and enhanced ascular permeability. Therefore, in essence, histamine is a rue neurohormone.