[A flow cytometric study of the effects of benzalkonium chloride on the cell cycle]

The effects of benzalkonium chloride (BAK) on the cell cycle of Chang's cultured human conjunctival cells were investigated by a flow cytometer (FCM). The cells were exposed to BAK solutions for 60 sec and after 12-48 hrs were fixed in 20% ethanol, treated by 0.25% RNase and stained by 0.005% propidium iodide. DNA histograms were analyzed by the FCM. As a result, although many cells were damaged by exposure to solutions of 0.0025% or 0.005% BAK, they began to grow again 48 hrs later. BAK decreased red fluorescence intensity in DNA histograms. The histogram shifted to the left 12 hrs after the cells were exposed to 0.0025% or 0.005% BAK solutions and recovered 48 hrs later. The DNA synthetic phase of the cell cycle was inhibited by exposure to solutions of 0.0025% BAK and then recovered 48 hrs later.