ObjectiveTo determine the effects of angiotensin II (AII) (1–8) on cytosolic free calcium concentrations in the absence and in the presence of the selective angiotensin subtype 1 (AT1) receptor antagonist losartan and of the selective angiotensin subtype 2-receptor antagonist P-186 in human peripheral blood mononuclear cells (PBMC). We also assessed the effect of the AII analogues AII (2–8), AII (3–8) and AII (4–8) on the cytosolic free-calcium concentration in human PBMC.MethodsThe cytosolic free-calcium concentration was assayed in human peripheral blood mononuclear cells by measuring the fluorescence of fura-2 entrapped by these cells.ResultsAdministration of AII caused a concentration-dependent increase in the cytosolic free-calcium concentration in human peripheral blood mononuclear cells with a half-maximal increase at 5 × 10−8mol/l. Also administration of the heptapeptide AII (2–8) increased the intracellular free-calcium concentration in human PBMC, whereas AII (3–8) and AII (4–8) had no effect. The AII (1–8)-induced rise in cytosolic free-calcium concentration was blocked completely by losartan but not by P-186.ConclusionOur data demonstrate that the effects of AII on the cytosolic free-calcium concentration in human PBMC are AT1receptor-mediated since they were abolished by the specific AII AT1receptor antagonist losartan but not by the specific angiotensin subtype 2 receptor antagonist P-186.