FIG. 1.

Preincubation time course of SMase induction of Stx sensitivity on endothelial cells. HDMEC were preincubated with SMase (0.067 U/ml) for the times indicated. Following the removal of SMase, the cells were incubated with purified Stx2 (0.1 nM) for 24 h, after which cell viability was determined as described in Materials and Methods. Data are presented as the means of results from triplicate samples, and cell viability is expressed as a percentage of the cell viability of the control sample, which was incubated in the absence of SMase and Stx2. These results are representative of results from multiple trials. The incubation of HDMEC with SMase alone did not reduce cell viability.