The recognition of histamine (HA)[or 2 (4-imidazolyl) ethylamine] as a messenger molecule in cell-to-cell communication began early in this century. The early history of HA was dominated by Sir Henry Dale, the great British pharmacologist; Barger and Dale (44) were the first to identify the amine in ergot extracts. Thereafter Dale and Laidlaw (151,152) described the major actions of HA on tissues, ie, its potent contractile effects on smooth muscles and the capillary dilative action. Popielski (579) described the only other important HA effect, the stimulant effect on gastric secretion. senger molecule, that is, that HA could be released from its tissue stores to affect the activity of target cells. It was Feldberg (211, 212) who clearly demonstrated that

In 1927, Dale and co-workers(68) were among the first to isolate HA from a variety of fresh tissues, thus establishing that HA is a normal constituent of the body. In fact its name derives from “histos,” the Greek word for tissue. However, Dale was reluctant to accept the notion that endogenous HA could function as a mes-