[Histonet] Muscarinic receptor detecting

I am currently trying to detect the existence of different muscarinic receptor subtypes in human tissues using immunofluorescence. My samples are OCT imbedded. I have tried fixation with 4% paraformaldehyde, acetone, acetone:methanol, 95% ethanol, neutral buffered formalin. I have used primary antibodies from R & D and Biogenesis. So far all the antibodies light up the whole cell with no intensified staining on the plasma membrane.

I wonder if any one has done stainings on muscarinic receptors or other 7 transmembrane protein receptors and like to share your success with me.