Direct Deviations in Astrocyte Free Ca2+ Concentration Control Multiple Arteriole Tone States

Astrocytes elicit bidirectional control of microvascular diameter in acutely isolated brain slices through vasoconstriction and vasodilation pathways that can be differentially recruited via the free Ca2+ concentration endfeet and/or metabolic status tissue. However, Ca2+-level hypothesis has not been tested using direct manipulation. To overcome this, we used Ca2+-clamp whole-cell patching peri-arteriole astrocytes to change astrocyte-free different concentrations examined vascular response. We discovered clamping at approximate resting value (100 nM) had no impact on arteriole a pre-constricted arteriole. moderate elevation 250 nM elicited sustained was blocked by COX-1 antagonist SC-560 (500 nM). The sensitive state, as it converted when oxygen tension dramatically elevated. In normal oxygen, astrocyte well above level (750 produced vasoconstriction, which 20-HETE blocker HET0016 (1 μM). This response fully addition nM), showing 20-HETE-induced dominated dilatory action COX-1. These data demonstrate changes multiple tone states mediators.