The effect of increasing [K+]0 on 3H-glycogen levels was examined in mouse cerebral cortical slices. K+ stimulates in a time- and concentration-dependent manner the hydrolysis of 3H-glycogen. Over 70% of the maximal effect is reached within 30 sec and the EC50 for the glycogenolytic action of K+ is 11 mM. Significant 3H-glycogen hydrolysis occurs at 5-12 mM [K+]0, concentrations reached by the ion in the extracellular space during neuronal activity. The K+-evoked glycogenolysis is Ca2+-dependent, and is inhibited by Ca2+-channel blockers such as Ni2+ and Mn2+, but not by Cd2+, nifedipine, and ω-conotoxin. Furthermore, the effect of K+ is not enhanced by the Ca2+-channel agonist Bay K 8644. This type of pharmacological profile suggests that the activation of voltage-sensitive Ca2+ channels of the T subtype mediates the glycogenolytic action of K+. This set of observations suggests that K+ released in the extracellular space by active neurons may promote the mobilization of energy substrates and therefore play a role in the coupling between neuronal activity and energy metabolism.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Neuroscience|
|State||Published - 1988|
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