Any Specific Vital Stains, Dyes? - (Sep/05/2008 )

I've been growing primary cardiac myocytes in layers of Matrigel to try and image some broad mechanics (with a confocal microscope). Of course, that calls for some strong but low-toxicity vital dyes. I've tried a few, with Calcein AM and Hoechst 33342 performing great. However, it's come to a point where I need to better discern the muscle cells from contaminating fibroblasts within the culture.

So is there such thing as cytoskeletal-specific vital dyes? I mean, phalloidin works without fixing, but kills the cells pretty quickly.