Using Fura-2AM microfluorimetry, we have shown for the first time that preincubation of macrophages with the calsequestrin inhibitor neuroleptic trifluoperazine leads to a significant inhibition of the store-dependent Ca ²⁺ entry induced by endoplasmic Ca ²⁺-ATPase inhibitors thapsigargin or cyclopiazonic acid in rat peritoneal macrophages. The results suggest calsequestrin involvement in the regulation of the store-dependent Ca ²⁺ entry in macrophages.