SRS -->
slow-reacting substance
medical dictionary

Slow-reacting substance of anaphylaxis (SRS-A), a leukotriene of low molecular weight which is released in anaphylactic shock and produces slower and more prolonged contraction of muscle than does histamine; it is active in the presence of antihistamines (but not epinephrine) and seems not to occur preformed in mast cells, but as a result of an antigen-antibody reaction on the granules.

Compare: peptidyl leukotrienes.

Synonyms: slow-reacting factor of anaphylaxis.

Acronym: SRS

(05 Mar 2000)