Effect of high extracellular [K+] on egress. At 30 h postinvasion, the culture medium was switched to either ECB, which allows K+ efflux, or ICB, which blocks K+ efflux. Percent egress is the percentage of lysed vacuoles at 42 h, 48 h, or 54 h postinvasion relative to the level at 30 h postinvasion. Data are means from three independent experiments. Error bars, standard deviations.