PSAC activity does not require sustained parasite viability. (A) Sorbitol-induced lysis time course with and without 200 μM furosemide (lower and upper curves, respectively) after cold storage for 7 days. The half-time in this lysis experiment, 6 minutes, is unchanged from that with viable parasites (Figure 3B and Wagner et al13 ). (B) Cold storage kills P falciparum trophozoites. Cultures were seeded immediately after percoll-sorbitol enrichment (day 0) or after storage at 4°C for 7 days; viability was assessed after 24 hours by counting the percentage of RBCs infected with ring-stage parasites (mean ± SEM, n = 3). The cold-stored culture was maintained for an additional week without the appearance of any parasites, verifying complete killing.
