title: Inhibition of suicidal erythrocyte death by probucol.
abstract: Probucol, an antioxidant and anti-inflammatory agent counteracting atherosclerosis and restenosis, is partially effective by influencing suicidal cell death or apoptosis. In analogy to apoptosis of nucleated cells, suicidal death of erythrocytes or eryptosis is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Eryptosis is stimulated by increase in cytosolic Ca(2+) activity, for example, after energy depletion or oxidative stress. The present study explored whether probucol influences eryptosis. Phosphatidylserine exposure was estimated from annexin-V-binding, cell volume from forward scatter (FSC), and cytosolic Ca(2+) concentration from fluo-3 fluorescence in flow cytometry. As a result, energy depletion (48-hour glucose removal) increased annexin-V-binding, decreased FSC, and increased fluo-3 fluorescence. Probucol (≤30 μM) did not significantly modify annexin-V-binding, FSC, or fluo-3 fluorescence in the presence of glucose but (at ≥5 μM) blunted the effect of glucose depletion on annexin-V-binding. Probucol (≥20 μM) only slightly blunted the effects of glucose depletion on FSC and fluo-3 fluorescence. Ca(2+) ionophore ionomycin (1 μM) and oxidative stress (30-minute exposure to 0.3 mM of tert-butylhydroperoxide) increased annexin-V-binding, effects again blunted by 30 μM of probucol. In conclusion, probucol blunts cell membrane scrambling after energy depletion and oxidative stress, effects primarily because of interference with the scrambling effects of increased cytosolic Ca(2+) concentration.
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany.
authors.forename: Nazneen
authors.initials: N
authors.lastname: Shaik
authors.forename: Adrian
authors.initials: A
authors.lastname: Lupescu
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D048429:Cell Size; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D005434:Flow Cytometry; D005947:Glucose / Q000378:metabolism; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects; D010718:Phosphatidylserines / Q000378:metabolism; D011341:Probucol / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D017304:Annexin A5; D000975:Antioxidants; D010718:Phosphatidylserines; D005947:Glucose; D011341:Probucol; D002118:Calcium