title: Amphiphile-induced phosphatidylserine exposure in human erythrocytes.
abstract: Nonionic and anionic water-soluble amphiphiles were shown to increase strongly the binding of fluorescein isothiocyanate-conjugated annexin V (FITC-annexin V) in human erythrocytes pretreated with the aminophospholipid translocase (APLT) inhibitor n-ethylmaleimide (NEM). At high sublytic amphiphile-concentrations the binding of FITC-annexin V, monitored in a flow cytometer, was time- and temperature-dependent and occurred heterogeneously in the cell population, with 43-81% of cells being stained above background following incubation for 60 minutes at 37 degrees C. The increased FITC-annexin V binding apparently indicates an increased flop rate of phosphatidylserine (PS) to the outer membrane leaflet. When the NEM-pretreatment was omitted, the FITC-annexin V binding was markedly, but not completely, reduced. In erythrocytes incubated with a zwitter-ionic amphiphile, a small increase in FITC-annexin V binding was detected, while cationic amphiphiles did not induce an increased FITC-annexin V binding. The potency of amphiphiles to induce PS exposure was not related to the type of shape alteration or vesiculation induced. Our results indicate a significant role of the charge status of a membrane intercalated amphiphile for its capability to induce PS exposure.
authors.affiliation: Department of Biology, Abo Akademi University, Turku, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Hägerstrand
authors.forename: T H
authors.initials: TH
authors.lastname: Holmström
authors.forename: M
authors.initials: M
authors.lastname: Bobrowska-Hägerstrand
authors.forename: J E
authors.initials: JE
authors.lastname: Eriksson
authors.forename: B
authors.initials: B
authors.lastname: Isomaa
mesh_terms: D017304:Annexin A5 / Q000737:chemistry / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate; D006801:Humans; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry / Q000378:metabolism
chemical_list: D017304:Annexin A5; D010718:Phosphatidylserines; D010743:Phospholipids; D013501:Surface-Active Agents; D016650:Fluorescein-5-isothiocyanate