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Astrocytic endfoot Ca2+ and BK channels determine both arteriolar dilation and constriction.


ABSTRACT: Neuronal activity is thought to communicate to arterioles in the brain through astrocytic calcium (Ca(2+)) signaling to cause local vasodilation. Paradoxically, this communication may cause vasoconstriction in some cases. Here, we show that, regardless of the mechanism by which astrocytic endfoot Ca(2+) was elevated, modest increases in Ca(2+) induced dilation, whereas larger increases switched dilation to constriction. Large-conductance, Ca(2+)-sensitive potassium channels in astrocytic endfeet mediated a majority of the dilation and the entire vasoconstriction, implicating local extracellular K(+) as a vasoactive signal for both dilation and constriction. These results provide evidence for a unifying mechanism that explains the nature and apparent duality of the vascular response, showing that the degree and polarity of neurovascular coupling depends on astrocytic endfoot Ca(2+) and perivascular K(+).

SUBMITTER: Girouard H 

PROVIDER: S-EPMC2840528 | biostudies-other | 2010 Feb

REPOSITORIES: biostudies-other

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Astrocytic endfoot Ca2+ and BK channels determine both arteriolar dilation and constriction.

Girouard Hélène H   Bonev Adrian D AD   Hannah Rachael M RM   Meredith Andrea A   Aldrich Richard W RW   Nelson Mark T MT  

Proceedings of the National Academy of Sciences of the United States of America 20100202 8


Neuronal activity is thought to communicate to arterioles in the brain through astrocytic calcium (Ca(2+)) signaling to cause local vasodilation. Paradoxically, this communication may cause vasoconstriction in some cases. Here, we show that, regardless of the mechanism by which astrocytic endfoot Ca(2+) was elevated, modest increases in Ca(2+) induced dilation, whereas larger increases switched dilation to constriction. Large-conductance, Ca(2+)-sensitive potassium channels in astrocytic endfeet  ...[more]

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