Do H1 and H2 blockers block mediators other than histamine? 

Do H1 and H2 blockers block mediators other than histamine? 

In another lecture, Dr. Dempsey talked about it affecting Heparin. Are there other mediators that it affects? 

Yeah, that's a good question. At the simple level, an H1 or H2 blocker is basically an antihistamine, and so they can block histamine receptors depending on which one, all over the body. That is blocking the histamine that the Mast Cells are producing, but Mast Cells themselves have histamine receptors on their surface. 

So, these antihistamines can bind to the Mast Cell and actually,  basically send a signal to the Mast Cell to stop degranulating, stop releasing other mediators. It's not specifically stopping Heparin, it's just one of the mediators we talked about in that lecture, but it's really stabilizing the Mast Cell in a way so that it stops reacting, in addition to the way it's actually acting in the perforae by blocking histamine.