SRS and the Related Substances

Abstract

The term SRS, slow reacting substance, refers to substances which show the slow contracting effect on smooth muscles, usually ileum, and has been first named by Feldberg et al. (1938). These workers found SRS in a perfusate from isolated lung by the addition of cobra venom, and also in a incubation fliud of egg-yolk with cobra venom. The occurrence of SRS following challenge of sensitized tissue with the specific antigen was reported by Kellaway et al.in 1940. Hitherto the studies about SRS have been mainly carried out on sensitized tissues. Recently Brocklehurst and Herxheimer et al.strongly suggested that this substance was one of the important spasmogens in bronchial asthma of human for their experiments in vitro or in situ. Although this term has been in use for about 30 years, the isolation of pure substances possessing SRS-activity is not yet reported. Thus SRS is merely a temporary term and must be replaced when the actual active substances will be properly isolated and characterized. In our laboratory, three active substances which show SRS-activity have been isolated from the shocked lung of guinea-pigs by means of fractionation with sephadex LH-20, and some of their properties, physicochemical and biological, are described.