Fig. 4. Short exposures to extracellular ATP or UTP do not interfere with dye coupling. The histogram shows the proportion of dye-coupled ATP-s cells when treated with 100 µM and 500 µM ATP or UTP. The drugs were applied 5 minutes before the experiment and maintained in the culture during the injection procedure. Data represent the mean±s.d. number of injected cells that displayed dye coupling in an individual Petri-dish culture. At least 30 cells per dish were injected with Lucifer Yellow, for a total of 90 cells injected. No difference was observed between ATP-s cells treated or untreated with extracellular ATP and UTP (P>0.05).