The title is a bit long but it might be okay as some sort of secondary title. Anyway, my biological knowledge isn't really sufficient to correct it, I think. Merely because I don't have a clue as to what kind of experimental study you're talking about, haha. The structure of a "relationship/relation between" sentence is usually like this though:
An experimental study of the relation(ship) between "A" and "B".
or, with more than 2 factors:
An experimental study of the relation(ship) between "A", "B", "..." , "..." and "Z".
So basically, I think you're using "and" too many times. I don't know whether the study is about the relationship between all these factors or about some of them. My guess is that it's better this way:
"An experimental study of the relation(ship) between Cilazapril、Valsartan, mRNA, protein expressions of atrial Calpains and atrial structural remodeling in atrial fibrillation dogs."