Effects of mefloquine and thapsigargin treatment on viability of rat neurons in vitro . A: The effect of mefloquine (Mef, 10 or 80 μM for 5 min), before and after pretreatment with thapsigargin (Thaps, 1 μM or DMSO, 0.4% for 5 min), on the viability of rat neurons was assessed using the MTT assay. Data shown are from eight replicate experiments. There was a significant interaction between mefloquine and thapsigargin (two way ANOVA, P < 0.01, n = 48). Thapsigargin had a neuroprotective effect against the toxic action of mefloquine, as indicated by the partial prevention (by 60%) of the reduction in viability (A540 units) caused by mefloquine.