Pratish Thakore,1 Michael G Alvarado,1 Sher Ali,1 Amreen Mughal,2 Paulo W Pires,3 Evan Yamasaki,1 Harry AT Pritchard,1,4 Brant E Isakson,5,6 Cam Ha T Tran,7 and Scott Earley1
1Department of Pharmacology, Reno School of Medicine (United States); 2Department of Pharmacology, University of Vermont (United States); 3Department of Physiology, University of Arizona (United States); 4Institute of Cardiovascular Sciences, University of Manchester (United Kingdom); 5Department of Molecular Physiology and Biological Physics, University of Virginia (United States); 6Robert M. Berne Cardiovascular Research Center, University of Virginia (United States)
7Department of Physiology & Cell Biology, Reno School of Medicine (United States)"
Calcium Imaging, Neuroscience
"Cerebral blood flow is dynamically regulated by neurovascular coupling to meet the dynamic metabolic demands of the brain. We hypothesized that TRPA1 channels in capillary endothelial cells are stimulated by neuronal activity and instigate a propagating retrograde signal that dilates upstream parenchymal arterioles to initiate functional hyperemia. We find that activation of TRPA1 in capillary beds and post-arteriole transitional segments with mural cell coverage initiates retrograde signals that dilate upstream arterioles. These signals exhibit a unique mode of biphasic propagation. Slow, short-range intercellular Ca2+ signals in the capillary network are converted to rapid electrical signals in transitional segments that propagate to and dilate upstream arterioles. We further demonstrate that TRPA1 is necessary for functional hyperemia and neurovascular coupling within the somatosensory cortex of mice in vivo. These data establish endothelial cell TRPA1 channels as neuronal activity sensors that initiate microvascular vasodilatory responses to redirect blood to regions of metabolic demand.
Baseline Ca2+ activity was recorded for the first 60 s (~1380 frames), then the capillary bed was picospritzed with AITC (30 µM) or ATP (10 µM), and the preparations were recorded for an additional 60 s (~1380 frames). Videos were obtained using a custom-built upright microscope (Olympus BX51 WI) equipped with epifluorescence illumination (CoolLED pE-300white, CoolLED Ltd., UK), a 20x water-immersion objective (numerical aperture 0.5, Olympus), and an ORCA-Fusion Digital CMOS C14440-20UP camera.
Product Associated Features
CoolLED’s pE-300white offers intense, broad-spectrum LED illumination to excite a range of fluorophores, including the calcium indicator GCaMP8.
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