Calum Wilson

• Doctor of Engineering
• Lecturer at University of Strathclyde

Key points The endothelium plays a pivotal role in the vascular response to chemical and mechanical stimuli. The endothelium is exquisitely sensitive to ACh, although the physiological significance of ACh‐induced activation of the endothelium is unknown. In the present study, we investigated the mechanisms of flow‐mediated endothelial calcium signa...

Endothelial cells are reported to be glycolytic and to minimally rely on mitochondria for ATP generation. Rather than providing energy, mitochondria in endothelial cells may act as signaling organelles that control cytosolic Ca2+ signaling or modify reactive oxygen species (ROS). To control Ca2+ signaling, these organelles are often observed close...

Pressure myography, one of the most commonly used techniques in vascular research, measures the diameter of isolated, pressurized arteries to assess the functional activity of smooth muscle and endothelial cells. Despite the widespread adoption of this technique for assessing vascular function, there are only a small number of commercial systems an...

Endothelial cells line all blood vessels and are critical regulators of vascular tone. In hypertension, disruption of endothelial function alters the release of endothelial-derived vasoactive factors and results in increased vascular tone. Although the release of endothelial-derived vasodilators occurs in a Ca2+-dependent manner, little is known on...

Background Obesity is a major risk factor for diabetes and cardiovascular diseases such as hypertension, heart failure, and stroke. Impaired endothelial function occurs in the earliest stages of obesity and underlies vascular alterations that give rise to cardiovascular disease. However, the mechanisms that link weight gain to endothelial dysfuncti...

An increase in cytoplasmic Ca²⁺ concentration activates multiple cellular activities, including cell division, metabolism, growth, contraction and death. In smooth muscle Ca²⁺ entry via voltage‐dependent Ca²⁺ channels leads to a relatively uniform increase in cytoplasmic Ca²⁺ levels that facilitates co‐ordinated contraction throughout the cell. How...

VasoTracker 2 is an open-source platform for studying blood vessel dynamics, featuring versatile diameter-tracking software and complementary low-cost hardware components. This system surpasses existing tools through accessible, high-resolution analysis across multiple imaging modalities, enabling comprehensive assessment of vascular dynamics in bo...

Introduction Endothelial cell (EC) ion channels regulate blood vessel diameter via calcium-dependent nitric oxide production and plasma membrane hyperpolarization. While the role of calcium-permeable cation channels is well established, the physiological significance of EC anion channels is less understood. Recently, the calcium-activated chloride...

BACKGROUND Endothelial cell TRPV4 (transient receptor potential vanilloid 4) channels provide a control point that is pivotal in regulating blood vessel diameter by mediating the Ca ²⁺ -dependent release of endothelial-derived vasoactive factors. In hypertension, TRPV4-mediated control of vascular function is disrupted, but the underlying mechanism...

The contractility of vascular smooth muscle cells (VSMCs) is a major contributor of vascular tone and blood pressure. In VSMCs, intracellular Ca ²⁺ level determines the contractile activity that generates the force to contract arteries. A major source of Ca ²⁺ is via influx through voltage dependent Ca ²⁺ channels (VDCCs). While mitochondria are no...

Introduction: The coordination of blood flow in response to localized increases in metabolic activity is vital for tissue function. This adaptive response typically involves the release of vasoactive factors leading to local vasodilation. This local vasodilation must propagate upstream to proximal feed arterioles and arteries to ensure a coordinate...

The endothelium is a sophisticated coordination center that controls a wide range of vascular functions, which include the regulation of blood pressure and blood flow via changes in vascular contractility. To coordinate vascular function, cell communication and interactions are required for tissue level responses to emerge. A significant form of ce...

The endothelium is the innermost layer of all blood vessels. It controls numerous cardiovascular functions including vascular contractility, haemostasis, inflammation and the exchange of nutrients and waste products between circulating blood and tissue. To control each cardiovascular function, the endothelium processes and responds to endless strea...

Background and Purpose The single layer of cells lining all blood vessels, the endothelium, is a sophisticated signal co‐ordination centre that controls a wide range of vascular functions including the regulation of blood pressure and blood flow. To co‐ordinate activities, communication among cells is required for tissue level responses to emerge....

Background: Endothelial cell TRPV4 channels provide a control point that is pivotal in regulating blood vessel diameter by mediating the Ca2+-dependent release of endothelial-derived vasoactive factors. In hypertension, TRPV4-mediated control of vascular function is disrupted but the underlying mechanisms, and precise physiological consequences rem...

Pyruvate is oxidized to acetyl‐CoA by pyruvate dehydrogenase which is localized in the mitochondrial matrix. The mitochondrial pyruvate carrier (MPC) is composed of SLC54 family members (MPC1 and MPC2) [1, 5], which form functional hetero-dimers [9, 8]. The MPC is expressed in the inner mitochondrial membrane and involved in the import of pyruvate...

Protease-activated receptor-1 &-2 (PAR1 and PAR2) are expressed widely in cardiovascular tissues including endothelial and smooth muscle cells. PAR1 and PAR2 may regulate blood pressure via changes in vascular contraction or relaxation mediated by endothelial Ca 2+ signaling, but the mechanisms are incompletely understood. By using single-cell Ca 2...

Arteries and veins are lined by non-proliferating endothelial cells that play a critical role in regulating blood flow. Endothelial cells also regulate tissue perfusion, metabolite exchange, and thrombosis. It is thought that endothelial cells rely on ATP generated via glycolysis, rather than mitochondrial oxidative phosphorylation, to fuel each of...

Significance The endothelium is the single layer of cells lining all blood vessels and acts as a central control hub to regulate multiple cardiovascular functions in response to hundreds of physiological stimuli. The detection of various physiological stimuli is distributed in spatially separated sites across the endothelium. Distributed sensing is...

Protease activated receptors (PARs), a subfamily of G‐protein‐coupled receptors, are activated by cleavage of its extracellular domains. Four mammalian PAR members have been identified (PAR1‐4). PAR1 is the thrombin receptor, while PAR2 is activated physiologically by peptides or N‐terminal proteolytic cleavage. The resulting cleaved N‐termini acts...

The endothelium is the innermost layer of all blood vessels and it controls a host of cardiovascular functions including vascular contractility, hemostasis, inflammation and the exchange of nutrients and waste products between circulating blood and tissue. The importance of the endothelium is clear since changes in the behaviour of this single laye...

Arteries and veins are lined by non‐proliferating endothelial cells that play a critical role in regulating blood flow. Endothelial cells also regulate tissue perfusion, metabolite exchange, and thrombosis. It is thought that endothelial cells rely on ATP generated via glycolysis to fuel each of these energy‐demanding processes. However, endothelia...

The endothelium is a sheet of highly‐specialised cells that line every blood vessel. Endothelial cells detect, integrate and respond to information from numerous signals, passing this information to neighbouring endothelial cells via intercellular communication to coordinate vascular contractility, inflammation and exchange of products between the...

Background and Purpose Ca²⁺ influx via TRPV4 channels triggers Ca²⁺ release from the IP3‐sensitive internal store to generate repetitive oscillations. Although mitochondria are acknowledged regulators of IP3‐mediated Ca²⁺ release, how TRPV4‐mediated Ca²⁺ signals are regulated by mitochondria is unknown. We show that depolarised mitochondria switch...

Arteries and veins are lined by non-proliferating endothelial cells that play a critical role in regulating blood flow. Endothelial cells also regulate tissue perfusion, metabolite exchange, and thrombosis. It is thought that endothelial cells rely on ATP generated via glycolysis to fuel each of these energy-demanding processes. However, endothelia...

Mitochondria are significant regulators of intracellular Ca2+ signalling in the vascular endothelium. Depolarization of the mitochondrial membrane potential (Δψm) inhibits IP3-mediated Ca2+ release and may regulate Ca2+ influx across the plasma membrane. However, precisely how Ca2+ influx is regulated by mitochondria in the endothelium is unknown....

Background and Purpose Ca influx via TRPV4 triggers Ca release from the IP-sensitive internal store to generate repetitive oscillations. While mitochondria are acknowledged regulators of IP-mediated Ca release, how TRPV4-mediated Ca signals are regulated by mitochondria is unknown. We show that depolarised mitochondria switch TRPV4 signalling from...

Photouncaging delivers compounds with high spatial and temporal control to induce or inhibit biological processes but the released compounds may diffuse out. We here demonstrate that sulfonate anions can be...

Background and Purpose Coordinated endothelial control of cardiovascular function is proposed to occur by endothelial cell communication via gap junctions and connexins. To study intercellular communication, the pharmacological agents carbenoxolone (CBX) and 18β‐glycyrrhetinic acid (18βGA) are used widely as connexin inhibitors and gap junction blo...

Pyruvate is oxidized to acetyl‐CoA by pyruvate dehydrogenase which is localized in the mitochondrial matrix. The mitochondrial pyruvate carrier (MPC) is a hetero-oligomer composed of SLC54 family members (MPC1 and MPC2). The MPC is expressed in the inner mitochondrial membrane and involved in the import of pyruvate into mitochondria [1, 5]. Ubiquit...

Rationale Obesity is a major risk factor for diabetes and cardiovascular diseases such as hypertension, heart failure, and stroke. Impaired endothelial function occurs in the earliest stages of obesity and underlies vascular alterations giving rise to cardiovascular disease. However, the mechanisms that link weight gain to endothelial dysfunction a...

Background and Purpose FK506 and rapamycin are modulators of FK‐binding proteins (FKBP) that are used to suppress immune function after organ and hematopoietic stem cell transplantations. The drugs share the unwanted side‐effect of evoking hypertension that is associated with reduced endothelial function and nitric oxide production. The underlying...

Side viewing GRIN imaging systems may be used to investigate calcium signalling events in the vascular endothelium. However, curvature of the artery wall and inherent field curvature in the GRIN system serve to degrade image field of view and resolution. In this work we quantify these aberrations, with an aim to introduce corrections into the imagi...

Hydrogen peroxide (H2O2) is a mitochondrial-derived reactive oxygen species (ROS) that regulates vascular signalling transduction, vasocontraction and vasodilation. Although the physiological role of ROS in endothelial cells is acknowledged, the mechanisms underlying H2O2 regulation of signalling in native, fully-differentiated endothelial cells is...

Rapid imaging of multiple focal planes without sample movement may be achieved through remote refocusing, where imaging is carried out in a plane conjugate to the sample plane. The technique is ideally suited to studying the endothelial and smooth muscle cell layers of blood vessels. These are intrinsically linked through rapid communication and mu...

Background and Purpose The TRPV4 ion channels are Ca²⁺ permeable, non‐selective cation channels that mediate large, but highly localized, Ca²⁺ signals in the endothelium. The mechanisms that permit highly localized Ca²⁺ changes to evoke cell‐wide activity are incompletely understood. Here, we tested the hypothesis that TRPV4‐mediated Ca²⁺ influx ac...

The endothelium is the single layer of cells lining all blood vessels, and it is a remarkable cardiovascular control centre. Each endothelial cell has only a small number (on average six) of interconnected neighbours. Yet this arrangement produces a large repertoire of behaviours, capable of controlling numerous cardiovascular functions in a flexib...

The endothelium is the innermost layer of all blood vessels and changes in the behavior of this single layer of cells underlie almost all cardiovascular disease. To regulate cardiovascular function, the endothelium must integrate hundreds of signals. These signals can arrive from as close as neighboring cells to substances circulating in the blood...

Hydrogen peroxide (H 2 O 2 ) is a key mitochondrial derived reactive oxygen species (ROS) that acts as a signalling hub in regulating signalling transduction, vasocontraction and vasodilation. Although the physiological roles of ROS in mechano‐stress signal transduction, vascular relaxation and permeability of endothelial cells is acknowledged, the...

Pressure myography has long been the gold standard technique for assessing the function of blood vessels ex vivo . The technique utilizes diameter measurement of isolated, pressurized arteries to report on the functional activity of smooth muscle and/or endothelial cells. However, despite the capability of the pressure myograph to assess vascular f...

The vascular endothelium lines the the entire vascular network and is a critical regulator of vascular tone given its ability to sense the complex composition of vasoactive substances in the circulating blood, as well as hemodynamic stresses and mechanical forces acting on the blood vessel wall. TRPV4 is a Ca ²⁺ permeable cation channel which is ex...

The endoplasmic reticulum (ER) is integral to the regulation of cytoplasmic Ca ²⁺ concentration in endothelial cells. Ca ²⁺ release from the ER is controlled by two intracellular receptor/channel complexes, the inositol 1,4,5‐triphosphate receptor (IP3R) and the ryanodine receptor (RyR). These receptors have been shown to be regulated by the access...

Rapid multiplane imaging is often required when imaging dynamic processes at high magnification in live samples. However, during rapid focus switching, image quality is compromised by the repeated, rapid agitation of the sample itself and movement of the immersion medium used for the high NA lens. Remote refocusing has been successful in minimising...

Blood flow, blood clotting, angiogenesis, vascular permeability, and vascular remodeling are each controlled by a large number of variable, noisy, and interacting chemical inputs to the vascular endothelium. The endothelium processes the entirety of the chemical composition to which the cardiovascular system is exposed, carrying out sophisticated c...

The endothelium is the innermost layer of blood vessels and it is a complex signal processing centre that controls almost all cardiovascular function. The endothelium uses a multitude of receptors to detect multiple simultaneously arriving extracellular signals that provide cues to physiological state and to determine cellular responses. Ca ²⁺ sign...

Endothelial cells have a dense mitochondrial complement. However, ATP production in endothelial cells is largely independent of mitochondrial oxidative pathways. As a result, the regulation of endothelial function by mitochondria has, in contrast to smooth muscle cells, been neglected and the precise role of the organelle is unresolved. We recently...

The endothelium is a complex network of cells that lines the entire vasculature and controls virtually all cardiovascular functions. Changes in the behaviour of endothelial cells underlies almost all cardiovascular disease. To regulate cardiovascular function, the endothelium integrates hundreds of signals that provide constant instructions. Signal...

The vascular endothelium is the innermost layer of cells lining blood vessels and is the key regulator of vascular tone. A critical feature of endothelial signalling, in the control of vascular function, is the endothelium's ability to coordinate function by communicating information between cells. Changes in the intracellular Ca ²⁺ concentration i...

The endothelium is the innermost lining of blood vessels and plays a significant role in controlling virtually every cardiovascular function. Constant signalling among endothelial cells and between endothelial cells and blood cells and smooth muscle cells is critical for the control of blood fluidity, vascular tone and angiogenesis. Intracellular C...

The endothelium is the single, innermost, layer of cells in blood vessels and it controls almost all cardiovascular functions. The endothelium regulates immune responses, blood coagulation, angiogenesis, vessel repair, and vascular permeability. To regulate function, the endothelium continuously monitors multiple chemicals that are circulating in t...

In small arteries, increased vascular reactivity contributes to the raised blood pressure that characterizes established hypertension. Endothelial function is altered in hypertension and may confer protection against the increased vascular reactivity but the precise mechanisms involved are unresolved. Here, in isolated small mesenteric arteries fro...

Calcium Imaging Across Large Areas of Intact Vascular Endothelium Reveals Stimulus-Specific Sensory Cells

The endothelium is the single layer of cells that lines the entire cardiovascular system and regulates vascular tone and blood–tissue exchange, recruits blood cells, modulates blood clotting, and determines the formation of new blood vessels. To control each function, the endothelium uses a remarkable sensory capability to continuously monitor vani...

Aging is the summation of many subtle changes which result in altered cardiovascular function. Impaired endothelial function underlies several of these changes and precipitates plaque development in larger arteries. The endothelium transduces chemical and mechanical signals into changes in the cytoplasmic calcium concentration to control vascular f...

Movie S9. Flow‐mediated Ca2+ signalling in mesenteric artery endothelia is abolished by atropine. The movie shows two sequential experimental recordings obtained from a single en face carotid artery preparation. The first recording shows a control response to flow (flow was initiated at t = 17 s). The second recording shows a response to flow in th...

Movie S3. Exogenous ACh augments flow‐mediated Ca2+ signalling. Ca2+ signalling was examined in a cut‐opened (en face) preparation of an carotid artery in which the endothelium was loaded with the Ca2+ indicator, Cal‐520/AM. The timescale of the Ca2+ imaging recording is indicated at the top right of the movie panel. Flow (1.5 ml min−1) was initiat...

Movie S4. Flow‐mediated Ca2+ signals originate in distinct subcellular locations. The movie shows active Ca2+ wavefronts (green; obtained by sequential subtraction of raw imaging data) overlaid on a single Ca2+ image (grey; obtained by averaging raw imaging data). The movie begins at the onset of flow, and is first played before being rewound and p...

Movie S7. Prolonged activation of TRPV4 channels induces large‐scale propagating Ca2+ waves in en face carotid artery preparations. The movie shows active Ca2+ wavefronts (green; obtained by sequential subtraction of raw imaging data) overlaid on a single Ca2+ image (grey; obtained by averaging raw imaging data). Scale bar = 50 μm.

Movie S1. Flow‐mediated Ca2+ signals in the endothelium of a carotid artery. Ca2+ signalling was examined in a cut‐opened (en face) preparation of an artery in which the endothelium was loaded with the Ca2+ indicator, Cal‐520/AM. The movie shows a raw 5 min long Ca2+ imaging recording (left; Played at 10× speed) and baseline‐corrected Ca2+ signals...

Movie S6. Activation of TRPV4 channels induces local Ca2+ signals followed by global Ca2+ increases in en face carotid artery preparations. The movie begins just prior to the onset of activation (t = 20 s) by the specific TRPV4 agonist, GSK1016790A (30 nm). Scale bar = 50 μm.

Movie S8. Flow‐mediated Ca2+ signalling in carotid artery endothelia is abolished by atropine. The movie shows three sequential experimental recordings obtained from a single en face carotid artery preparation. The first recording shows a control response to flow (flow was initiated at t = 15 s). The second recording shows a control response during...

Movie S2. Flow‐mediated Ca2+ signals in the endothelium of a second‐order mesenteric artery. Ca2+ signalling was examined in a cut‐opened (en face) preparation of an artery in which the endothelium was loaded with the Ca2+ indicator, Cal‐520/AM. The timescale of the Ca2+ imaging recording is indicated at the top right of the movie panel. Flow (1.5...

Movies S5. Spontaneous Ca2+ signals in the endothelium of a mesenteric artery. Ca2+ signalling was examined in a cut‐opened (en face) preparation of an artery in which the endothelium was loaded with the Ca2+ indicator, Cal‐520/AM. The movie shows a raw 60 s long Ca2+ imaging recording (left) and a binary image highlighting locations of spontaneous...

In smooth muscle, Ca2+ release from the internal store into the cytoplasm occurs via inositol trisphosphate (IP3R) and ryanodine receptors (RyR). The internal Ca2+ stores containing IP3R and RyR may be arranged as multiple separate compartments with various IP3R and RyR arrangements, or there may be a single structure containing both receptors. The...

The flow of blood generates mechanical forces (e.g. shear‐stress) that are important physiological regulators of vascular tone. The vascular endothelium senses these forces and, in response, releases various vasodilators (e.g. nitric oxide) that relax smooth muscle cells in a process termed flow‐mediated vasodilation. Whilst some elements of the si...

Agonist-mediated signaling by the endothelium controls virtually all vascular functions. Because of the large diversity of agonists, each with varying concentrations, background noise often obscures individual cellular signals. How the endothelium distinguishes low-level fluctuations from noise and decodes and integrates physiologically relevant in...

Movie S2. ACh activated IP3‐evoked endothelial Ca2+ signals which were recorded from inside pressurized arteries. At 60 mmHg, ACh caused an initial burst of Ca2+ increases that propagate as waves. As ACh‐evoked Ca2+ waves expanded collision between adjacent cells occurred and wave annihilation occurred. As a result of multiple waves progressions an...

Movie S3. ACh activated IP3‐evoked Ca2+ signals were significantly attenuated as the artery transmural pressure increased from 60 mmHg to 110 mmHg to 160 mmHg. After each application of ACh the bath solution was washed with >20 times the bath volume, and the artery was allowed to re‐equilibrate for 20 minutes before the next pressure change and ACh...

Movie S1. ACh‐evoked endothelial Ca2+ signals in a pressurised (60 mmHg) rat carotid artery. Activation of IP3‐evoked endothelial Ca2+ signals, by bath application of ACh (100 μM), causes a rise in cytoplasmic Ca2+ concentration in the majority of cells across the field of view. The movie is composed of raw data, to which a 5‐frame rolling average...

Key points Increased pressure suppresses endothelial control of vascular tone but it remains uncertain (1) how pressure is sensed by the endothelium and (2) how the vascular response is inhibited. This study used a novel imaging method to study large numbers of endothelial cells in arteries that were in a physiological configuration and held at nor...

Aging is the summation of many, mostly invisible, but deleterious changes associated with altered structure and function of the cardiovascular system. Age‐induced impairment of endothelial function contributes to and reinforces the changes that occur in vascular disease. Normally, the endothelium transduces multiple chemical and mechanical signals...

Ca ²⁺ signalling in the endothelium is central to the control of vascular function and to the changes that occur in vascular disease. However, visualizing Ca ²⁺ signals in endothelial cells in intact, pressurised arteries is difficult (particularly in the larger arteries where atherosclerosis and re‐stenosis occurs), due to medial and adventitial t...

The diversity of mitochondrial arrangements, which arise from the organelle being static or moving, or fusing and dividing in a dynamically reshaping network, is only beginning to be appreciated. While significant progress has been made in understanding the proteins that reorganise mitochondria, the physiological significance of the various arrange...

Communication between the endothelium and smooth muscle is central to the control of vascular function. However, understanding this communication has been hampered by an inability to simultaneously measure the various signalling events that occur in endothelial and smooth muscle cells in arteries at physiological pressures. Here we describe the dev...

Mitochondrial Ca(2+) uptake contributes important feedback controls to limit the time course of Ca(2+) signals. Mitochondria regulate cytosolic [Ca(2+) ] over an exceptional breath of concentrations (~200 nM to > 10 μM) to provide a wide dynamic range in the control of Ca(2+) signals. Ca(2+) uptake is achieved by passing the ion down the electroche...

Objective: Mitochondria are widely described as being highly dynamic and adaptable organelles, and their movement is thought to be vital for cell function. Yet, in various native cells, including those of heart and smooth muscle, mitochondria are stationary and rigidly structured. The significance of the differences in mitochondrial behavior to th...