By 1913 the name histamine was in use, using combining forms of histo- + amine, yielding "tissue amine". "H substance" or "substance H" are occasionally used in medical literature for histamine or a hypothetical histamine-like diffusible substance released in allergic reactions of skin and in the responses of tissue to inflammation.

[ 53 ] The properties of histamine, then called β-imidazolylethylamine, were first described in 1910 by the British scientists Henry H. Dale and P.P. Laidlaw. [ 54 ] By 1913 the name histamine was in use, using combining forms of histo- + amine, yielding "tissue amine".

Mast cells. Most histamine in the body is generated in granules in mast cells and in white blood cells (leukocytes) called basophils. Mast cells are especially numerous at sites of potential injury – the nose, mouth, and feet, internal body surfaces, and blood vessels.

Histamine receptors are members of the rhodopsin family (class A) of 7-transmembrane receptors and consist of a single polypeptide chain that spans the membrane seven times, with the amino terminus being extracellular and the carboxy terminus intracellular. You might find these chapters and articles relevant to this topic.