Histamine and a Lipid‐Soluble Smooth‐Muscle Stimulating Principle (‘SRS’) in Anaphylactic Reaction

The relationship between the occurrence of histamine and ‘SRS’ in anaphylactic reaction was investigated in guinea‐pig tissue. The temperature and pH curves for histamine and ‘SRS’ were similar. Anoxia and lack of calcium inhibited equally the appearance of both. When histamine release was inhibited by polymeric enzyme inhibitors or by an organic dye, there was concomitant inhibition of ‘SRS’. Moreover, enzyme inhibitors which react with sulphydryl or amino groups — iodoacetate, allicin, 2:.l‐dinitrofluoro‐benzene, phenylisocyanate and acetic anhydride — blocked both histamine and ‘SRS’. Glutathione and cysteine partly reversed the inhibitory effect of iodoacetate on both histamine and ‘SRS’. While histamine is released from a loose binding in the tissue, ‘SRS’ seems to be formed during anaphylactic reaction. The observations may be explained by postulating that antigen‐antibody reaction in anaphylaxis activates an enzyme system, probably with essential sulphydryl and amino groups in the mast cells, and results in the appearance of both histamine and ‘SRS’.