Decreased Redox-Sensitive Erythrocyte Cation Channel Activity in Aquaporin 9-Deficient Mice

Decreased Redox-Sensitive Erythrocyte Cation Channel Activity in Aquaporin 9-Deficient Mice Survival of the malaria pathogen Plasmodium falciparum in host erythrocytes requires the opening of new permeability pathways (NPPs) in the host cell membrane, accomplishing entry of nutrients, exit of metabolic waste products such as lactate and movement of inorganic ions such as Cl−, Na+ and Ca2+. The molecular identity of NPPs has remained largely elusive but presumably involves several channels, which partially can be activated by oxidative stress in uninfected erythrocytes. One NPP candidate is aquaporin 9 (AQP9), a glycerol-permeable water channel expressed in erythrocytes. Gene-targeted mice lacking functional AQP9 (aqp −/−) survive infection with the malaria pathogen Plasmodium berghei better than their wild-type littermates (aqp9 +/+). In the present study whole-cell patch-clamp recordings were performed to explore whether ion channel activity is different in erythrocytes from aqp −/− and aqp9 +/+ mice. As a result, the cation conductance (K+ > Na+ > Ca2+ ≫ NMDG+) was significantly lower in erythrocytes from aqp −/− than in erythrocytes from aqp9 +/+ mice. Oxidative stress by exposure for 15–30 min to 1 mM H2O2 or 1 mM tert-butyl-hydroperoxide enhanced the cation conductance and increased cytosolic Ca2+ concentration, effects significantly less pronounced in erythrocytes from aqp −/− than in erythrocytes from aqp9 +/+ mice. In conclusion, lack of AQP9 decreases the cation conductance of erythrocytes, an effect that possibly participates in the altered susceptibility of AQP9-deficient mice to infection with P. berghei. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Decreased Redox-Sensitive Erythrocyte Cation Channel Activity in Aquaporin 9-Deficient Mice

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Publisher
Springer Journals
Copyright
Copyright © 2012 by Springer Science+Business Media, LLC
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-012-9482-y
Publisher site
See Article on Publisher Site

Abstract

Survival of the malaria pathogen Plasmodium falciparum in host erythrocytes requires the opening of new permeability pathways (NPPs) in the host cell membrane, accomplishing entry of nutrients, exit of metabolic waste products such as lactate and movement of inorganic ions such as Cl−, Na+ and Ca2+. The molecular identity of NPPs has remained largely elusive but presumably involves several channels, which partially can be activated by oxidative stress in uninfected erythrocytes. One NPP candidate is aquaporin 9 (AQP9), a glycerol-permeable water channel expressed in erythrocytes. Gene-targeted mice lacking functional AQP9 (aqp −/−) survive infection with the malaria pathogen Plasmodium berghei better than their wild-type littermates (aqp9 +/+). In the present study whole-cell patch-clamp recordings were performed to explore whether ion channel activity is different in erythrocytes from aqp −/− and aqp9 +/+ mice. As a result, the cation conductance (K+ > Na+ > Ca2+ ≫ NMDG+) was significantly lower in erythrocytes from aqp −/− than in erythrocytes from aqp9 +/+ mice. Oxidative stress by exposure for 15–30 min to 1 mM H2O2 or 1 mM tert-butyl-hydroperoxide enhanced the cation conductance and increased cytosolic Ca2+ concentration, effects significantly less pronounced in erythrocytes from aqp −/− than in erythrocytes from aqp9 +/+ mice. In conclusion, lack of AQP9 decreases the cation conductance of erythrocytes, an effect that possibly participates in the altered susceptibility of AQP9-deficient mice to infection with P. berghei.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 27, 2012

References

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