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Rapid decrease in cellular sodium and chloride content during cold incubation of cultured liver endothelial cells and
E R Gizewski1, U Rauen, M Kirsch
1Institut für Physiologische Chemie, Universitätsklinikum, Hufelandstrasse 55, D-45122 Essen, Germany.
The Biochemical Journal
|March 15, 1997
Summary
Contrary to popular belief, hypothermia during organ preservation causes cells to lose sodium and chloride, not accumulate them. This early sodium efflux challenges existing theories on cold preservation and cell ion balance.
Area of Science:
- Cellular physiology
- Transplantation medicine
- Biochemistry
Background:
- Hypothermia is standard for organ preservation in transplantation.
- It's widely believed that hypothermia inhibits Na+/K+-ATPase, causing intracellular sodium and chloride accumulation.
- This study investigates the actual ion dynamics during cold preservation.
Purpose of the Study:
- To challenge the prevailing assumption of sodium accumulation during hypothermia.
- To accurately measure intracellular sodium and chloride concentrations in cells during cold storage.
- To determine the direction of ion flux (influx vs. efflux) in the early stages of cold incubation.
Main Methods:
- Cultured liver endothelial cells were subjected to hypothermia in University of Wisconsin (UW) solution.
- Fluorescence microscopy was used to initially assess cellular sodium concentration.
- Capillary electrophoresis was employed to quantify cellular inorganic cations and anions, specifically sodium and chloride.
- Experiments were repeated using different cold incubation solutions and with cultured rat hepatocytes to assess solution and cell type specificity.
Main Results:
- A significant decrease (55%) in cellular sodium concentration was observed within 30 minutes of cold incubation in UW solution.
- Capillary electrophoresis confirmed a reduction in sodium from 104+/-11 to 55+/-4 nmol/mg protein and chloride from 71+/-9 to 25+/-5 nmol/mg protein.
- Similar early decreases in sodium and chloride were noted when using cold Krebs-Henseleit buffer or cell culture medium, indicating the effect is independent of the preservation solution.
- Cultured rat hepatocytes also showed a decrease in sodium content, suggesting the phenomenon is not cell-specific.
Conclusions:
- Contrary to established beliefs, cellular sodium and chloride efflux, rather than influx, predominates during the early phase of hypothermic cold incubation.
- These findings necessitate a re-evaluation of the cellular mechanisms underlying hypothermia-induced ion changes in organ preservation.
- The observed ion efflux challenges current models of cell behavior during cold storage and has implications for optimizing preservation strategies.