Author:

Keywords:

Angiotensin II, Calcium, Cytosol, Fluorescent Dyes, Fura-2, Humans, Monocytes, Peptide Fragments, Receptor, Angiotensin, Type 1, Receptor, Angiotensin, Type 2, Receptors, Angiotensin, Science & Technology, Life Sciences & Biomedicine, Peripheral Vascular Disease, Cardiovascular System & Cardiology, angiotensin II, mononuclear cells, cytosolic calcium, CONVERTING-ENZYME, BINDING, IDENTIFICATION, EXPRESSION, INCREASES, HYPERTENSION, MACROPHAGES, METABOLISM, SECRETION, PLATELETS, In Vitro Techniques, 1102 Cardiorespiratory Medicine and Haematology, 1103 Clinical Sciences, 1116 Medical Physiology, Cardiovascular System & Hematology, 3201 Cardiovascular medicine and haematology, 3202 Clinical sciences

Abstract:

OBJECTIVE: To 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. METHODS: The cytosolic free-calcium concentration was assayed in human peripheral blood mononuclear cells by measuring the fluorescence of fura-2 entrapped by these cells. RESULTS: Administration 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 x 10(-8) mol/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. CONCLUSION: Our data demonstrate that the effects of AII on the cytosolic free-calcium concentration in human PBMC are AT1 receptor-mediated since they were abolished by the specific AII AT1 receptor antagonist losartan but not by the specific angiotensin subtype 2 receptor antagonist P-186.