Biology subjects

Sancho, M.

Publications and source records attributed to Sancho, M..

10 recordsLinked to original sources

bioRxiv2026

Neurons entrain and shape an intrinsic arteriole rhythm that distributes blood across the cortical mantle

The cerebral arteriole network distributes blood across cortex through branches whose diameters oscillate near a frequency fvaso ~ 0.1 Hz. We asked whether the spatiotemporal pattern of these vaso-oscillations reflects neuronal entrainment of an intrinsic vascular oscillation. Three findings support this: First, suppressing endothelial hyperpolarization left resting-state oscillations intact but weakened the vascular response to neural activity, showing that vasomotion originates within the arteriole network rather than following neuronal drive. Second, arterioles amplify sensory drive selectively rather than faithfully: neural activity near 0.1 Hz is resonantly enhanced to form a strong peak in the vascular response. Third, neuronal frequency sets spatial reach, and areas compete: when two neighboring cortical areas are driven simultaneously, the one nearer fvaso captures more vascular territory. Neurons therefore entrain an intrinsic vascular rhythm and stimulation frequency governs how vasomotion distributes blood, shapes functional brain images, and may influence interstitial fluid transport.

neuroscience↗

bioRxiv2026

Electromechanical Dynamics and Myogenic Responses in Cerebral Smooth Muscle Cells and Capillary Pericytes

Cerebral blood flow (CBF) control is essential for normal brain function and is disrupted in pathological conditions. Arterial diameters are tightly regulated to provide on demand increases in blood flow in regions of neuronal activity. Pericytes (PCs) exhibit robust myogenic tone and may also respond to neuronal activity to fine-tune local resistance and blood flow. Thus, mural control of microcirculatory resistance may extend beyond arteries and arterioles. Yet, PCs electrophysiology and contractility have not been thoroughly characterized, and this prohibits an integrated view of brain blood flow control. In this study, we develop a detailed mathematical model of mural cell electrophysiology, Ca2+ dynamics and biomechanics. The model is informed by electrophysiological data in smooth muscle cells (SMCs) or PCs and predictions are compared against pressure-induced responses in isolated arterioles and capillaries, respectively. Simulations recapitulate myogenic constrictions and examine differences in contractile dynamics as we move from arterioles to proximal and distal capillaries. In arteriole-to-capillary transitional (ACT) zone PCs, increased mechanosensitivity, more Ca2+ influx through non-selective cation (NSC) channels and/or a higher sensitivity of the contractile apparatus to Ca2+ can compensate for reduced L-type voltage-operated (VOCC) Ca2+ influx and allow for robust constrictions at the lower operating pressures of capillaries relative to the arterioles. A significant Ca2+ influx through NSC relative to VOCC, however, can decouple the PCs contractile apparatus from electrical signaling. Vasoactivity to chemomechanical stimuli along the arteriole to capillary axis is progressively driven by VOCC-independent Ca2+ influx and Ca2+ sensitization with slow kinetics. The proposed cell model can form the basis for detailed multiscale and multicellular models that will examine physiological function at a single vessel or vascular network levels and investigate CBF control in health and in disease. Key pointsO_LIA mural cell model of electrophysiology, calcium (Ca2+) dynamics and biomechanics is informed by data and adapted for modeling cerebral arteriole smooth muscle cells and capillary pericytes. C_LIO_LIIon channel activities are characterized by patch-clamp electrophysiology in isolated cerebral smooth muscle cell and pericytes, and capillary and arteriole electromechanical responses to transmural pressure changes are assessed using novel ex vivo preparations. C_LIO_LIMyogenic constrictions in arterioles can be reproduced by pressure-induced non-selective cation channel (NSC) activation that depolarizes the cell, opens L-type Ca2+ channels (VOCCs) and increases Ca2+ influx. C_LIO_LIRobust myogenic constrictions in arteriole-to-capillary transition (ACT) zone pericytes may reflect significant Ca2+ influx through NSC, increased mechanosensitivity, or higher sensitivity of the contractile apparatus to Ca2+, potentially compensating for reduced VOCC density relative to arteriolar smooth muscle. C_LIO_LIA significant contribution of NSC relative to VOCC in Ca2+ influx, can decouple the contractile apparatus from electrical signaling. C_LIO_LIThe model shows how gradients in ionic activities, mechanosensitivity and/or Ca2+ sensitivity can alter contractile phenotype and electromechanical coupling along the arteriole to capillary continuum. C_LIO_LIThe proposed model can form the basis for detailed multiscale and multicellular models that will investigate cerebral blood flow control in health and in disease. C_LI

physiology↗

bioRxiv2025

Endothelial Arf6 sustains capillary electrical signaling and cerebral blood flow through PIP2 regeneration and activation of Kir2.1 channels.

Brain capillaries sense neural activity and direct blood flow to active regions--a process termed neurovascular coupling that underlies activity-dependent increases in local perfusion (functional hyperemia). A key contributor to functional hyperemic responses is the capillary endothelial cell (cEC) inward rectifier K+ (Kir2.1) channel, which is activated by neuronal activity-derived extracellular K+ and initiates vasodilatory electrical signals that propagate through the vascular network. Kir2.1 channel function requires continual production of its lipid cofactor, phosphatidylinositol-4,5-bisphosphate (PIP2), and is compromised in mouse models of cerebral small vessel (cSVD). Although decreased PIP2 availability is a common feature of cSVD, mechanisms underlying PIP2 synthesis remain poorly understood. We hypothesized that Arf6, a small GTPase expressed in cECs that stimulates PIP2 production, is critical for this process. Using patch-clamp electrophysiology, we demonstrate that inhibiting Arf6 activity progressively decreased cEC Kir2.1 channel activity. This deficit corresponded to loss of capillary-to-arteriole electrical signaling in isolated vessels and diminished functional hyperemia in vivo. Exogenously provided PIP2 restored Kir2.1 currents and functional hyperemia after Arf6 inhibition or genetic knockdown. Collectively, our data indicate that cEC Arf6 sustains Kir2.1 activity by maintaining PIP2 levels and demonstrate that diminished PIP2 synthesis is sufficient to impair functional hyperemia. Furthermore, we identify Arf6 as a mechanistic link between PIP2 production and endothelial electrical signaling, highlighting Arf6 as a potential therapeutic target for restoring functional hyperemia. Significance StatementActive brain regions send electrical signals through capillaries to dilate upstream arterioles and increase blood flow. The resulting activity-dependent increase in local blood flow (functional hyperemia) is mediated through inward-rectifier potassium (Kir2.1) channels. These channels-- and hence functional hyperemia--require continuous regeneration of the lipid cofactor PIP2 (phosphatidylinositol-4,5-bisphosphate). If PIP2 is deficient, electrical signaling fails--a defect characteristic of models of cerebral small vessel disease and Alzheimers disease. We identify the small GTPase Arf6 as a key to maintaining PIP2 and thus preserving capillary Kir2.1 activity and functional hyperemia. Our findings reveal an important pathway for PIP2 homeostasis and position Arf6 as a cornerstone upholding functional hyperemic responses, highlighting Arf6 as a target for restoring cerebral blood flow in disease.

neuroscience↗

bioRxiv2025

Adenosine and acute low oxygen conditions suppress urinary bladder contractility through the activation of adenosine 2B receptors and large-conductance calcium-activated potassium channels

Under healthy conditions the urinary bladder undergoes relatively long periods of filling with well-spaced voiding events to ensure proper storage and removal of urine respectively. During the filling phase, distinct contractile events in detrusor urinary smooth muscle (UBSM) elicit transient non-voiding pressure events and associated bursts in afferent nerve activity to relay the sensation of bladder fullness. The mechanisms that regulate UBSM excitability and associated non-voiding pressure events under physiological and pathological conditions are poorly understood. Here we investigated the role of adenosine signaling in regulating urinary bladder contractility. Using an ex vivo pressurized bladder preparation from mice and patch-clamp electrophysiology in isolated UBSM we evaluated whole bladder transient pressure events, whole bladder detrusor Ca2+ activity, and single UBSM ion channel activity. We found that adenosine suppresses bladder activity through activation of A2B adenosine receptors and downstream activation of large-conductance calcium-activated potassium (BKCa) channels. We further demonstrated that acute exposure to low oxygen conditions using a chemical oxygen scavenger potently suppresses bladder contractility through the A2B receptor pathway. These results highlight the prominent role adenosine receptors and downstream potassium channels play in regulating urinary bladder contractility in physiological and pathological contexts.

physiology↗

bioRxiv2023

CaV3.1 Channels Facilitate Calcium Wave Generation and Myogenic Tone Development in Mouse Mesenteric Arteries.

BackgroundThe myogenic response is the mechanism whereby intraluminal pressure elicits arterial constriction pursuant to the maintenance of tissue perfusion. Smooth muscle [Ca2+] is a key determinant of constriction, a process intimately tied to L-type (CaV1.2) Ca2+ channels. While important, other Ca2+ channels, in particular T-type, are expressed and could contribute to pressure regulation within defined voltage ranges. This study examined the role of one T-type Ca2+ channel using mesenteric arteries from C57BL/6 wild type and CaV3.1-/- mice. MethodsPatch-clamp electrophysiology, pressure myography, non-invasive blood pressure measurements and rapid Ca2+ imaging were employed to define the CaV3.1-/- phenotype relative to C57BL/6. Proximity ligation assay tested the closeness of CaV3.1 channels to inositol triphosphate receptors (IP3R). Nifedipine (0.3 M) and 2-APB (50 M) were used to block L-type Ca2+ channels and IP3Rs, respectively. ResultsInitial experiments confirmed the absence of CaV3.1 expression and whole-cell current in global deletion mice, a change that coincided with a reduction in systemic blood pressure. Mesenteric arteries from CaV3.1-/- mice produced less myogenic tone than C57BL/6, particularly at lower pressures (20-60 mmHg) where membrane potential is more hyperpolarized. This reduction in myogenic tone correlated with diminished Ca2+ wave generation in the CaV3.1-/- mice. These asynchronous events are dependent upon Ca2+ release from the sarcoplasmic reticulum which is insensitive to L-type Ca2+ channel blockade. A close physical association (<40 nm) between IP3R1 and CaV3.1 was confirmed by proximity ligation assay; blockade of IP3R in nifedipine-treated C57BL/6 arteries rendered a CaV3.1-/- contractile phenotype. ConclusionFindings indicate that Ca2+ influx through CaV3.1 channels contributes to myogenic tone development at hyperpolarized voltages by triggering a Ca2+-induced Ca2+ release mechanism tied to the sarcoplasmic reticulum. This study helps establish CaV3.1 as a potential therapeutic target in the control of blood pressure. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=160 SRC="FIGDIR/small/528095v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1b3fe9forg.highwire.dtl.DTLVardef@11954borg.highwire.dtl.DTLVardef@607417org.highwire.dtl.DTLVardef@65964c_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

bioRxiv2021

Electro-Metabolic Sensing Through Capillary ATP-Sensitive K+ Channels and Adenosine to Control Cerebral Blood Flow

The dense network of capillaries composed of capillary endothelial cells (cECs) and pericytes lies in close proximity to all neurons, ideally positioning it to sense neuro/glial-derived compounds that regulate regional and global cerebral perfusion. The membrane potential (VM) of vascular cells serves as the essential output in this scenario, linking brain activity to vascular function. The ATP-sensitive K+ channel (KATP) is a key regulator of vascular VM in other beds, but whether brain capillaries possess functional KATP channels remains unknown. Here, we demonstrate that brain capillary ECs and pericytes express KATP channels that robustly control VM. We further show that the endogenous mediator adenosine acts through A2A receptors and the Gs/cAMP/PKA pathway to activate capillary KATP channels. Moreover, KATP channel stimulation in vivo causes vasodilation and increases cerebral blood flow (CBF). These findings establish the presence of KATP channels in cECs and pericytes and suggest their significant influence on CBF. HIGHLIGHTSO_LICapillary network cellular components--endothelial cells and pericytes--possess functional KATP channels. C_LIO_LIActivation of KATP channels causes profound hyperpolarization of capillary cell membranes. C_LIO_LICapillary KATP channels are activated by exogenous adenosine via A2A receptors and cAMP-dependent protein kinase. C_LIO_LIKATP channel activation by adenosine or synthetic openers increases cerebral blood flow. C_LI

neuroscience↗

bioRxiv2021

Traumatic Brain Injury Impairs Systemic Vascular Function Through Altered Lipid Metabolism and Disruption of Inward-Rectifier Potassium (Kir2.1) Channels

BACKGROUND AND PURPOSETrauma can lead to widespread vascular endothelial dysfunction, but the underlying mechanisms remain largely unknown. Strong inward-rectifier potassium channels (Kir2.1) play a critical role in the dynamic regulation of regional perfusion and blood flow. Kir2.1 channel activity is modulated by phosphatidylinositol 4,5-bisphosphate (PIP2), a minor membrane phospholipid that is degraded by phospholipase A2 (PLA2) in conditions of oxidative stress or severe inflammation. We hypothesized that PLA2-induced depletion of PIP2 impairs Kir2.1 channel function. METHODSA fluid percussion injury model of traumatic brain injury (TBI) in rats was used to study mesenteric resistance arteries 24 hours after injury. Patch-clamp electrophysiology in freshly isolated endothelial and smooth muscle cells was performed to monitor Kir2.1 conductance, and the functional responses of intact arteries were assessed using pressure myography. We analyzed circulating PLA2, hydrogen peroxide (H2O2), and metabolites to identify alterations in signaling pathways associated with PIP2 in TBI. RESULTSElectrophysiology analysis of endothelial and smooth muscle cells revealed a significant reduction of Ba2+-sensitive Kir2.1 currents after TBI. Additionally, dilations to elevated extracellular potassium and BaCl2- or ML 133-induced constrictions in pressurized arteries were significantly decreased following TBI, consistent with an impairment of Kir2.1 channel function. The addition of a PIP2 analog to the patch pipette successfully rescued endothelial Kir2.1 currents after TBI. Both H2O2 and PLA2 activity were increased after injury. Metabolomics analysis demonstrated altered lipid metabolism signaling pathways, including increased arachidonic acid, and fatty acid mobilization after TBI. CONCLUSIONSOur findings support a model in which increased H2O2-induced PLA2 activity after trauma hydrolyzes endothelial PIP2, resulting in impaired Kir2.1 channel function.

physiology↗

bioRxiv2020

Differences in mitochondrial activity trigger cell competition during early mouse development.

Cell competition is emerging as a quality control mechanism that eliminates unfit cells in a wide range of settings from development to the adult. However, the nature of the cells normally eliminated by cell competition and what triggers their elimination remains poorly understood. In mouse, prior to gastrulation 35% of epiblast cells are eliminated. Here we have performed single cell transcriptional profiling of these cells and find that they show the hallmarks of cell competition and have mitochondrial defects. We demonstrate that mitochondrial defects are common to a range of different loser cell types and that manipulating mitochondrial function is sufficient to trigger competition. Importantly, we show that in the embryo cell competition eliminates cells with mitochondrial DNA mutations and that even non-pathological changes in mitochondrial DNA sequence can induce cell competition. Our results therefore suggest that cell competition is a purifying selection that optimises mitochondrial performance prior to gastrulation.

developmental biology↗

bioRxiv2019

Intercellular Conduction Optimizes Arterial Network Function and Conserves Blood Flow Homeostasis during Cerebrovascular Challenges

Cerebral arterial networks match blood flow delivery with neural activity. Neurovascular response begins with a stimulus and a focal change in vessel diameter, which by themselves is inconsequential to blood flow magnitude, until they spread and alter the contractile status of neighboring arterial segments. We sought to define the mechanisms underlying integrated vascular behavior and considered the role of intercellular electrical signalling in this phenomenon. Electron microscopic and histochemical analysis revealed the structural coupling of cerebrovascular cells and the expression of gap junctional subunits at the cell interfaces, enabling intercellular signaling among vascular cells. Indeed, robust vasomotor conduction was detected in human and mice cerebral arteries after focal vessel stimulation; a response attributed to endothelial gap junctional communication, as its genetic alteration attenuated this behavior. Conducted responses was observed to ascend from the penetrating arterioles, influencing the contractile status of cortical surface vessels, in a simulated model of cerebral arterial network. Ascending responses recognised in vivo after whisker stimulation, were significantly attenuated in mice with altered endothelial gap junctional signalling confirming that gap junctional communication drives integrated vessel responses. The diminishment in vascular communication also impaired the critical ability of the cerebral vasculature to maintain blood flow homeostasis and hence tissue viability, after stroke. Our findings establish the integral role of intercellular electrical signalling in transcribing focal stimuli into coordinated changes in cerebrovascular contractile activity and expose, a hitherto unknown mechanism for flow regulation after stroke.\n\nSignificanceNeurovascular responses are viewed as a one step process whereby stimuli derived from neural cells focally diffuse to a neighboring vessel, altering its contractile state. While focal changes in tone can subtly tune flow distribution, they cant substantively change \"perfusion magnitude\" as vascular resistance is broadly distributed along the cerebral arterial tree. We report that nature overcomes this biophysical constraint by conducting electrical signals among coupled vascular cells, along vessels, and across branch points. Our quantitative exploration of intercellular conduction illustrates how network coordination optimizes blood flow delivery in support of brain function. Diminishing the ability of vascular cells to electrically communicate, mitigates the brains ability to regulate perfusion during functional hyperemia and after stroke, the latter advancing tissue injury.

neuroscience↗

bioRxiv2018

Membrane Lipid-KIR2.x Channel Interactions Enable Hemodynamic Sensing in Cerebral Arteries

Inward rectifying (KIR) K+ channels are present in cerebral arterial smooth muscle and endothelial cells, a tandem arrangement suggestive of a dynamic yet undiscovered role for this channel. We explored whether vascular KIR channels were uniquely modulated by membrane lipids and hemodynamic stimuli. A KIR current was isolated in smooth muscle and endothelial cells of rat cerebral arteries and molecular analyses confirmed KIR2.1/KIR2.2 mRNA and protein expression. Electrophysiology next revealed that endothelial KIR was sensitive to phosphatidylinositol 4,5- bisphosphate (PIP2), with depletion impairing flow-induced activation of the channel. In contrast, smooth muscle KIR was sensitive to membrane cholesterol, with sequestration blocking pressures ability to inhibit this channel. Membrane lipids helped confer KIR mechanosensitivity to intact arteries; virtual models then reconceptualised KIR as a dynamic regulator of basal tone development. We conclude that specific membrane lipid-KIR interactions enable unique channel populations to sense hemodynamic stimuli and set brain perfusion.

neuroscience↗