![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Leukotriene_C4.svg/640px-Leukotriene_C4.svg.png&w=640&q=50)
Slow-reacting substance of anaphylaxis
From Wikipedia, the free encyclopedia
The slow-reacting substance of anaphylaxis or SRS-A is a mixture of the leukotrienes LTC4, LTD4 and LTE4. Mast cells secrete it during the anaphylactic reaction, inducing inflammation.[1] It can be found in basophils.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Leukotriene_C4.svg/320px-Leukotriene_C4.svg.png)
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Leukotriene_D4.svg/320px-Leukotriene_D4.svg.png)
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Leukotriene_E4.svg/320px-Leukotriene_E4.svg.png)
It induces prolonged, slow contraction of smooth muscle and has a major bronchoconstrictor role in asthma.[2] Compared to histamine, it is approximately 1000 times more potent and has a slower onset but longer duration of action.[citation needed]