The production of histamine from histidine by ultra-violet light and the absorption spectra of these substances

Abstract

It has been shown by Lewis and his co-workers (1927) that when the human skin is irritated by mechanical or chemical stimuli, by heat or cold, or by ultra-violet light, the triple response which occurs is due to the liberation of the so-called H-substance. Lewis considers that it is probable that this substance is a normal product of metabolism, the production or liberation of which is enhanced by various forms of irradiation. The chemical identification of the various substances liberated under these conditions is not possible, but they are found to possess so many physiological properties in common with histamine that there can be little doubt that this base is actually present among them. It has been shown chemically that histamine can normally be obtained from extracts of liver and lung (Best, Dale, Dudley and Thorpe, 1927) and other tissues. Alcoholic extracts of most other tissues (Thorpe, 1928) including skin (Harris, 1927) also contain substances which possess the pharmacological properties of histamine and are almost certainly identical with it. Extracts made in other ways have similar properties, and there seems to be no reason to doubt that histamine is normally present as such, in varying quantities, in different tissues. Neither the source nor the ultimate fate of this histamine is definitely known, but it has been shown that the appearance of H-substance in the tissue spaces may be associated with the disappearance of histamine from the cells (Harris, 1927).