Related Experiment Videos
Competition between Li+ and Mg2+ for red blood cell membrane phospholipids: A 31P, 7Li, and 6Li nuclear magnetic
C Srinivasan1, N Minadeo, C F Geraldes
1Department of Chemistry, Loyola University Chicago, Illinois 60626, USA.
Lipids
|December 22, 1999
Summary
Lithium ion (Li+) binds strongly to anionic phospholipids in red blood cell membranes, suggesting a key role for these lipids in lithium
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- The mechanism of lithium ion (Li+) in treating bipolar illness remains unclear despite its long clinical use.
- Previous studies suggest competition between Li+ and magnesium ions (Mg2+) in biological systems.
Purpose of the Study:
- To investigate Li+ and Mg2+ interactions with red blood cell (RBC) membrane components.
- To determine if Li+/Mg2+ competition occurs within RBC membranes.
Main Methods:
- 31P nuclear magnetic resonance (NMR) chemical shift measurements of extracted RBC phospholipids.
- 6Li and 7Li spin-lattice relaxation measurements on RBC membranes.
Main Results:
- Anionic phospholipids (phosphatidylserine, phosphatidylinositol) exhibit the strongest binding affinity for both Li+ and Mg2+.
- Lithium binding constants to phospholipid extracts were determined.
- Removal of the RBC cytoskeleton significantly increased Li+ binding to exposed anionic phospholipids.
Conclusions:
- Phospholipids play a significant role in metal ion binding within RBC membranes.
- The RBC cytoskeleton does not appear to be a major factor in Li+ binding or Li+/Mg2+ competition.