Biology subjects

Pires, P. W.

Publications and source records attributed to Pires, P. W..

2 recordsLinked to original sources

bioRxiv2023

BKCa nitrosylation is associated with cerebral microvascular dysfunction in female 5x-FAD mice

BackgroundCerebral microvascular dysfunction and nitro-oxidative stress are present in patients with Alzheimers disease (AD) and may contribute to disease progression and severity. Large conductance Ca2+-activated K+ channels (BKCa) play an essential role in vasodilatory responses and maintenance of myogenic tone in resistance arteries. BKCa impairment can lead to microvascular dysfunction and hemodynamic deficits in the brain. We hypothesized that reduced BKCa function in cerebral arteries mediates microvascular and neurovascular responses in the 5x-FAD model of AD. MethodsBKCa activity in the cerebral microcirculation was assessed by patch clamp electrophysiology and pressure myography, in situ Ca2+ sparks by spinning disk confocal microscopy, hemodynamics by laser speckle contrast imaging. Molecular and biochemical analyses were conducted by affinity-purification assays, qPCR, Western blots and immunofluorescence. ResultsWe observed that pial arteries from 5-6 months-old male and female 5x-FAD mice exhibited a hyper-contractile phenotype than wild-type (WT) littermates, which was linked to lower vascular BKCa activity and reduced open probability. In males, BKCa dysfunction is likely a consequence of an observed lower expression of the pore-forming subunit BK and blunted frequency of Ca2+ sparks, which are required for BKCa activity. However, in females, impaired BKCa function is, in part, a consequence of reversible nitro-oxidative changes in the BK subunit, which reduces its open probability and regulation of vascular tone. We further show that BKCa function is involved in neurovascular coupling in mice, and its dysfunction is linked to neurovascular dysfunction in the model. ConclusionThese data highlight the central role played by BKCa in cerebral microvascular and neurovascular regulation, as well as sex-dependent mechanisms underlying its dysfunction in a mouse model of AD.

physiology↗

bioRxiv2020

Brain Endothelial Cell TRPA1 Channels Initiate Neurovascular Coupling

Blood flow regulation in the brain is dynamically regulated to meet the metabolic demands of active neuronal populations. Recent evidence has demonstrated that capillary endothelial cells are essential mediators of neurovascular coupling that sense neuronal activity and generate a retrograde, propagating, hyperpolarizing signal that dilates upstream arterioles. Here, we tested the hypothesis that transient receptor potential ankyrin 1 (TRPA1) channels in capillary endothelial cells are significant contributors to functional hyperemic responses that underlie neurovascular coupling in the brain. Using an integrative ex vivo and in vivo approach, we demonstrate the functional presence of TRPA1 channels in brain capillary endothelial cells, and show that activation of these channels within the capillary bed, including the post-arteriole transitional region covered by ensheathing mural cells, initiates a retrograde signal that dilates upstream parenchymal arterioles. Notably, this signaling exhibits a unique biphasic mode of propagation that begins within the capillary network as a short-range, Ca2+ signal dependent on endothelial pannexin-1 channel/purinergic P2X receptor communication pathway and then is converted to a rapid, inward-rectifying K+ channel-mediated electrical signal in the post-arteriole transitional region that propagates upstream to parenchymal arterioles. Two-photon laser-scanning microscopy further demonstrated that conductive vasodilation occurs in vivo, and that TRPA1 is necessary for functional hyperemia within the somatosensory cortex of mice. Together, these data establish a role for endothelial TRPA1 channels as sensors of neuronal activity and show that they respond accordingly by initiating a vasodilatory response that redirects blood to regions of metabolic demand.

neuroscience↗