A method for staining 3T3 cell nuclei with propidium iodide in hypotonic solution

A modification of the propidium-iodide hypotonic sodium citrate method has been developed specifically for high-resolution staining of mouse 3T3 cell nuclei for analysis by flow cytometry. The method employs a brief treatment of cells at 37 degrees C with Triton X-100 and RNAse in the presence of propidium iodide in hypotonic sodium citrate, followed by restoration to isotonicity with NaCl. The average CV obtained for the G1 peak was 3.5%, and the samples were stable for 1-2 weeks at 4 degrees C. Compared to this technique, previously described propidium iodide-staining methods gave poor resolution with 3T3 cells.