Comparison between the effects of the microsomal Ca(2+)-translocase inhibitors thapsigargin and 2,5-di-(t-butyl)-1,4-benzohydroquinone on cellular calcium fluxes.

The effects of two inhibitors of the microsomal Ca(2+)-ATPase, thapsigargin and 2,5-di-(t-butyl)-1,4-benzohydroquinone, were compared in hepatocytes and in a T-cell line (JURKAT). Both compounds mobilized the same intracellular Ca2+ pool, which contained the Ins(1,4,5)P3-sensitive store, in hepatocytes and in JURKAT cells. The mobilization of the internal Ca2+ store with either compound activated Mn2+ entry in JURKAT cells, but not in hepatocytes. This suggests different properties of the bivalent-cation entry pathway between these cell types.