title: Thermal inactivation of volume-sensitive K⁺,Cl⁻ cotransport and plasma membrane relief changes in human erythrocytes.
abstract: Previously, we reported that in mammalian erythrocytes irreversible annealing of spectrin heterodimers at 49-50 °C abolished cell volume-dependent regulation of ion carriers, thus suggesting an implication of a two-dimensional (2D) membrane carcass in volume sensing and/or signal transduction. To further examine this hypothesis, we employed atomic force microscopy. This method revealed folded membrane relief of fixed human erythrocytes with an average wave height of 3-5 nm covered by globular structures with a diameter of 40-50 nm and an average height of 1-2 nm. Erythrocyte swelling caused by reduction of medium osmolality decreased the height of membrane surface waves by 40 % and increased K(+),Cl(-) cotransport by approximately sixfold. Both volume-sensitive changes of membrane relief and activity of K(+),Cl(-) cotransporter were abolished by a 10-min preincubation at 50 °C. Our results strongly suggest that volume-dependent alterations of the human erythrocyte membrane relief are caused by reorganization of the 2D spectrin-actin network contributing to regulation of the activity of volume-sensitive ion transporters.
authors: Department of Biophysics and Laboratory of Physical Chemistry of Biomembranes, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia.
authors: E Yu
authors: EY
authors: Parshina
authors: A I
authors: AI
authors: Yusipovich
authors: A A
authors: AA
authors: Platonova
authors: R
authors: R
authors: Grygorczyk
authors: G V
authors: GV
authors: Maksimov
authors: S N
authors: SN
authors: Orlov
mesh_terms: D000199:Actins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure*; D002712:Chlorides / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D017136:Ion Transport; D018625:Microscopy, Atomic Force; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D013049:Spectrin / Q000378:metabolism; D027981:Symporters / Q000378:metabolism*; D000096922:K Cl- Cotransporters
chemical_list: D000199:Actins; D002712:Chlorides; D011188:Potassium; D013049:Spectrin; D027981:Symporters; D000096922:K Cl- Cotransporters
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