title: Micropipette aspiration of human erythrocytes induces echinocytes via membrane phospholipid translocation.
abstract: When a discocytic erythrocyte (RBC) was partially aspirated into a 1.5-microns glass pipette with a high negative aspiration pressure (delta P = -3.9 kPa), held in the pipette for 30 s (holding time, th), and then released, it underwent a discocyte-echinocyte shape transformation. The degree of shape transformation increased with an increase in th. The echinocytes recovered spontaneously to discocytes in approximately 10 min, and there was no significant difference in recovery time at 20.9 degrees C, 29.5 degrees C, and 37.4 degrees C, respectively. At 11 degrees C the recovery time was significantly elevated to 40.1 +/- 6.7 min. At 20.9 degrees C the shape recovery time varied directly with the isotropic RBC tension induced by the pipetting. Sodium orthovanadate (vanadate, 200 microM), which inhibits the phospholipid translocase, blocks the shape recovery. Chlorpromazine (CP, 25 microM) reversed the pipette-induced echinocytic shape to discocytic in < 2 min, and the RBC became a spherostomatocyte-II after another 30 min. It was hypothesized that the increase in cytosolic pressure during the pipette aspiration induced an isotropic tension in the RBC membrane followed by a net inside-to-outside membrane lipid translocation. After a sudden release of the aspiration pressure the cytosolic pressure and the membrane tension normalized immediately, but the translocated phospholipids remained temporarily "trapped" in the outer layer, causing an area excess and hence the echinocytic shape. The phospholipid translocase activity, when not inhibited by vanadate, caused a gradual return of the translocated phospholipids to the inner layer, and the RBC shape recovered with time.
authors.affiliation: Department of Applied Cell Biophysics, FH Aachen, Jülich, Germany. artmann@fh-aachen.de
authors.forename: G M
authors.initials: GM
authors.lastname: Artmann
authors.forename: K L
authors.initials: KL
authors.lastname: Sung
authors.forename: T
authors.initials: T
authors.lastname: Horn
authors.forename: D
authors.initials: D
authors.lastname: Whittemore
authors.forename: G
authors.initials: G
authors.lastname: Norwich
authors.forename: S
authors.initials: S
authors.lastname: Chien
mesh_terms: D001800:Blood Specimen Collection / Q000295:instrumentation / Q000379:methods; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000097:blood; D002746:Chlorpromazine / Q000494:pharmacology; D003600:Cytosol / Q000502:physiology; D004910:Erythrocyte Membrane / Q000502:physiology / Q000648:ultrastructure*; D004912:Erythrocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008563:Membrane Lipids / Q000097:blood*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000097:blood; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids / Q000097:blood*; D011312:Pressure; D012044:Regression Analysis; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D008563:Membrane Lipids; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D014638:Vanadates; D002746:Chlorpromazine