[Histonet] HCN4 staining

[Shaw, Sharon]

Hello,

I'm hoping somebody out there can give me some help with HCN4 staining, I was asked to stain HCN4 on mouse heart and it needs to stain the SA node. It is very hard to find that area since the node is very small. I have tried serial sections but not sure I hit the area or if I'm having problems with the stain.
The antibody is Rat monoclonal
Secondary Alexa Flour 488 goat anti-rat
Counter stain is Hoechst

I tried frozen and paraffin sections with no luck

Any suggestions will help greatly

Thanks,
Sharon