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. Author manuscript; available in PMC: 2014 Jul 15.
Published in final edited form as: Nature. 2008 Oct 29;456(7223):745–749. doi: 10.1038/nature07525

Fig. 1.

Fig. 1

Lowering O2 converts astrocyte-mediated vasoconstrictions to vasodilations. (a) Top: astrocytes (red) loaded with Ca2+ indicator surround arteriole. Bottom: astrocyte Ca2+ signals occur coincident with dilation caused by the mGluR agonist t-ACPD in low O2. (b) Top: uncaging astrocyte Ca2+ (indicated by arrow) causes vasodilation in low O2 and is repeatable. Bottom: expanded time scale shows the Ca2+ signal in endfoot 1 (shown in c I) precedes the lumen diameter increase. (c) Overlay of vessel and pseudo colored endfoot Ca2+ changes. Images I-V correspond to times in b. I: control state and regions of interest: endfeet 1-3. Image II: endfoot 1 shows first Ca2+ rise (star) before lumen diameter starts to increase. Vertical dotted line (III-V) indicates previous position of vessel wall. (d) Summary data.