K+ Homeostasis in the Brain: A New Role for Glycogenolysis
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The results of the study of Xu and colleagues in this issue constitute a critical new piece of information on the functional specialization of astrocytes for K+ homeostasis in the brain. The relationship between astrocytes and potassium has been long recognized in half a century of research. Now this relation appears to have found its metabolic correlate in astrocytic glycogen. Xu et al. showed that glycogen is committed to fuel astrocytic K+ uptake, as this process is abolished when glycogenolysis is inhibited even in the presence of glucose. They went further by showing that the cellular mechanisms which selectively mobilize glycogen involve the participation of several intracellular signaling cascades. As with all good science, these findings generate a number of fundamental questions that are open for experimental research.
KeywordsAstrocytes Potassium Glycogen Na+/K+-ATPase signaling
The author S.M. acknowledges the support by the NIH National Center for Research Resources (P41 RR008079, 1UL1 RR033183 and KL2 RR033182) and the National Institute of Biomedical Imaging and Bioengineering (P41 EB015894). Additional CMRR funding is from Minnesota Medical Foundation and NIH P30 NS076408.
- 3.Xu J, Song D, Xue Z, Gu L, Hertz L, Peng L. Requirement of glycogenolysis for uptake of increased extracellular K+ in astrocytes: potential implications for K+ homeostasis and glycogen usage in brain. Neurochem Res. doi: 10.1007/s11064-012-0938-3