Histamine

Histamine is one of a group of diverse substances that include: the biogenic amines, histamine and serotonin, small peptides, such as the kinins, and lipids, such as the prostaglandins and the chemically unidentified, slow reacting substance of anaphylaxis (SRS-A). All these substances are released from tissues during injury or inflammatory reactions. All produce edema when injected locally, alter blood pressure when injected systemically, and act on a variety of smooth-muscle preparations in vitro. Their actions can be attenuated, blocked, or potentiated by a variety of agents either by interacting at receptors or by blocking the enzymes that synthesize or metabolize . . .