Referenced in: none

Automatically associated channels: BKβ

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

Authors: Helene Girouard, Adrian D Bonev, Rachael M Hannah, Andrea Meredith, Richard W Aldrich, Mark T Nelson

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 2010 Feb 23 , 107, 3811-6

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20133576

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(+).