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Inhibition of erythrocyte phosphatidylserine exposure by urea and Cl-.

Lang, Karl S, Mysina, Svetlana, Lang, Philipp A, Tanneur, Valerie, Kempe, Daniela S, Mack, Andreas F, Huber, Stephan M, Wieder, Thomas, Lang, Florian and Duranton, Christophe (2004) Inhibition of erythrocyte phosphatidylserine exposure by urea and Cl-. American journal of physiology. Renal physiology, 286 (6). F1046-53. ISSN 1931-857X

Item Type: Article

Abstract

Osmotic shock by addition of sucrose to the medium stimulates erythrocyte sphingomyelinase with subsequent ceramide formation and triggers Ca(2+) entry through stimulation of cation channels. Both ceramide and Ca(2+) activate an erythrocyte scramblase, leading to breakdown of phosphatidylserine asymmetry, a typical feature of apoptosis. Because erythrocytes are regularly exposed to osmotic shock during passage of kidney medulla, the present study explored the influence of NaCl and urea on erythrocyte phosphatidylserine exposure as determined by annexin binding. The percentage of annexin-binding erythrocytes increased from <5 to 80 +/- 4% (n = 4) upon addition of 650 mM sucrose, an effect paralleled by activation of the cation channel and stimulation of ceramide formation. The number of annexin-binding erythrocytes increased only to 18% after addition of 325 mM NaCl and was not increased by addition of 650 mM urea. According to whole cell patch-clamp experiments, the cation conductance was activated by replacement of extracellular Cl(-) with gluconate at isotonic conditions or by addition of hypertonic sucrose or urea. Although stimulating the cation conductance, urea abrogated the annexin binding and concomitant increase of ceramide levels induced by osmotic cell shrinkage. In vitro sphingomyelinase assays demonstrated a direct inhibitory effect of urea on sphingomyelinase activity. Urea did not significantly interfere with annexin binding after addition of ceramide. In conclusion, both Cl(-) and urea blunt erythrocyte phosphatidylserine exposure after osmotic shock. Whereas Cl(-) is effective through inhibition of the cation conductance, urea exerts its effect through inhibition of sphingomyelinase, thus blunting formation of ceramide.

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More Information

Depositing User: Svetlana Mysina

Identifiers

Item ID: 10025
ISSN: 1931-857X
URI: http://sure.sunderland.ac.uk/id/eprint/10025

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Catalogue record

Date Deposited: 08 Oct 2018 09:13
Last Modified: 09 Oct 2018 11:16

Contributors

Author: Karl S Lang
Author: Svetlana Mysina
Author: Philipp A Lang
Author: Valerie Tanneur
Author: Daniela S Kempe
Author: Andreas F Mack
Author: Stephan M Huber
Author: Thomas Wieder
Author: Florian Lang
Author: Christophe Duranton

Subjects

Sciences > Biomedical Sciences

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