Livestreaming Can Augment the Observation of Veterinary Post-mortem Examinations.

The creation of interactive livestreaming post-mortem examination sessions for veterinary students is described, including the technological and pedagogical issues that were considered and a detailed description of the solution developed. We used the Hero 7 Go Pro camera ( https://gopro.com/en/gb ) and livestreamed using Zoom ( https://explore.

NO-induced vasodilation correlates directly with BP in smooth muscle-Na/Ca exchanger-1-engineered mice: elevated BP does not attenuate endothelial function.

Arterial smooth muscle Na/Ca exchanger-1 (SM-NCX1) promotes vasoconstriction or vasodilation by mediating, respectively, Ca influx or efflux. In vivo, SM-NCX1 mediates net Ca influx to help maintain myogenic tone (MT) and neuronally activated constriction. SM-NCX1-TG (overexpressing transgenic) mice have increased MT and mean blood pressure (MBP; +13.

Na/Ca exchanger overexpression in smooth muscle augments cytosolic Ca in femoral arteries of living mice.

Plasma membrane Na/Ca exchanger-1 (NCX1) helps regulate the cytosolic Ca concentration ([Ca]) in arterial myocytes. NCX1 mediates both Ca entry and exit and tends to promote net Ca entry in partially constricted arteries. Mean blood pressure (telemetry) is elevated by ≈10 mmHg in transgenic (TG) mice that overexpress NCX1 specifically in smooth muscle.

Hypoxia selectively upregulates cation channels and increases cytosolic [Ca] in pulmonary, but not coronary, arterial smooth muscle cells.

Ca signaling, particularly the mechanism via store-operated Ca entry (SOCE) and receptor-operated Ca entry (ROCE), plays a critical role in the development of acute hypoxia-induced pulmonary vasoconstriction and chronic hypoxia-induced pulmonary hypertension. This study aimed to test the hypothesis that chronic hypoxia differentially regulates the expression of proteins that mediate SOCE and ROCE [stromal interacting molecule (STIM), Orai, and canonical transient receptor potential channel TRPC6] in pulmonary (PASMC) and coronary (CASMC) artery smooth muscle cells. The resting cytosolic [Ca] ([Ca]) and the stored [Ca] in the sarcoplasmic reticulum were not different in CASMC and PASMC.

Imaging sympathetic neurogenic Ca signaling in blood vessels.

We review the information that has been provided by optical imaging experiments directed at understanding the role and effects of sympathetic nerve activity (SNA) in the functioning of blood vessels. Earlier studies utilized electric field stimulation of nerve terminals (EFS) in isolated arteries and vascular tissues (ex vivo) to elicit SNA, but more recently, imaging studies have been conducted in vivo, enabling the study of SNA in truly physiological conditions. Ex vivo: In vascular smooth muscle cells (VSMC) of isolated arteries, the three sympathetic neurotransmitters, norepinephrine (NE), ATP and neuropeptide Y (NPY), elicit or modulate distinct patterns of Ca signaling, as revealed by confocal imaging of exogenous fluorescent Ca indicators.

Pivotal role of α2 Na pumps and their high affinity ouabain binding site in cardiovascular health and disease.

Reduced smooth muscle (SM)-specific α2 Na pump expression elevates basal blood pressure (BP) and increases BP sensitivity to angiotensin II (Ang II) and dietary NaCl, whilst SM-α2 overexpression lowers basal BP and decreases Ang II/salt sensitivity. Prolonged ouabain infusion induces hypertension in rodents, and ouabain-resistant mutation of the α2 ouabain binding site (α2 mice) confers resistance to several forms of hypertension. Pressure overload-induced heart hypertrophy and failure are attenuated in cardio-specific α2 knockout, cardio-specific α2 overexpression and α2 mice.

Reduction of Mitochondria-Endoplasmic Reticulum Interactions by Acetylcholine Protects Human Umbilical Vein Endothelial Cells From Hypoxia/Reoxygenation Injury.

Objective: We explored the role of endoplasmic reticulum (ER)-mitochondria Ca(2+) cross talk involving voltage-dependent anion channel-1 (VDAC1)/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex and mitofusin 2 in endothelial cells during hypoxia/reoxygenation (H/R), and investigated the protective effects of acetylcholine.

Approach And Results: Acetylcholine treatment during reoxygenation prevented intracellular and mitochondrial Ca(2+) increases and alleviated ER Ca(2+) depletion during H/R in human umbilical vein endothelial cells. Consequently, acetylcholine enhanced mitochondrial membrane potential and inhibited proapoptotic cascades, thereby reducing cell death and preserving endothelial ultrastructure.

PC-PLC/sphingomyelin synthase activity plays a central role in the development of myogenic tone in murine resistance arteries.

Myogenic tone is an intrinsic property of the vasculature that contributes to blood pressure control and tissue perfusion. Earlier investigations assigned a key role in myogenic tone to phospholipase C (PLC) and its products, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). Here, we used the PLC inhibitor, U-73122, and two other, specific inhibitors of PLC subtypes (PI-PLC and PC-PLC) to delineate the role of PLC in myogenic tone of pressurized murine mesenteric arteries.

Ca(2+) signaling in arterioles and small arteries of conscious, restrained, optical biosensor mice.

Unlabelled: Two-photon fluorescence microscopy and conscious, restrained optical biosensor mice were used to study smooth muscle Ca(2+) signaling in ear arterioles. Conscious mice were used in order to preserve normal mean arterial blood pressure (MAP) and sympathetic nerve activity (SNA). ExMLCK mice, which express a genetically-encoded smooth muscle-specific FRET-based Ca(2+) indicator, were equipped with blood pressure telemetry and immobilized for imaging.

A method for noninvasive longitudinal measurements of [Ca2+] in arterioles of hypertensive optical biosensor mice.

We used two-photon (2-p) Förster resonance energy transfer (FRET) microscopy to provide serial, noninvasive measurements of [Ca(2+)] in arterioles of living "biosensor" mice. These express a genetically encoded Ca(2+) indicator (GECI), either FRET-based exMLCK or intensity-based GCaMP2. The FRET ratios, Rmin and Rmax, required for in vivo Ca(2+) calibration of exMLCK were obtained in isolated arteries.

Intravital Förster resonance energy transfer imaging reveals elevated [Ca2+]i and enhanced sympathetic tone in femoral arteries of angiotensin II-infused hypertensive biosensor mice.

Artery narrowing in hypertension can only result from structural remodelling of the artery, or increased smooth muscle contraction. The latter may occur with, or without, increases in [Ca(2+)]i. Here, we sought to measure, in living hypertensive mice, possible changes in artery dimensions and/or [Ca(2+)]i, and to determine some of the mechanisms involved.

High vascular tone of mouse femoral arteries in vivo is determined by sympathetic nerve activity via α1A- and α1D-adrenoceptor subtypes.

Background And Purpose: Determining the role of vascular receptors in vivo is difficult and not readily accomplished by systemic application of antagonists or genetic manipulations. Here we used intravital microscopy to measure the contributions of sympathetic receptors, particularly α1-adrenoceptor subtypes, to contractile activation of femoral artery in vivo.

Experimental Approach: Diameter and intracellular calcium ([Ca(2+)]i) in femoral arteries were determined by intravital fluorescence microscopy in mice expressing a Myosin Light Chain Kinase (MLCK) based calcium-calmodulin biosensor.

Vascular tone and Ca(2+) signaling in murine cremaster muscle arterioles in vivo.

Objectives: We sought to determine some of the molecular requirements for basal state "tone" of skeletal muscle arterioles in vivo, and whether asynchronous Ca(2+) waves are involved or not.

Methods: Cremaster muscles of anesthetized exMLCK and smGCaMP2 biosensor mice were exteriorized, and the fluorescent arterioles were visualized with wide-field, confocal or multiphoton microscopy to observe Ca(2+) signaling and arteriolar diameter.

Results: Basal state tone of the arterioles was ~50%.

Increased arterial smooth muscle Ca2+ signaling, vasoconstriction, and myogenic reactivity in Milan hypertensive rats.

The Milan hypertensive strain (MHS) rats are a genetic model of hypertension with adducin gene polymorphisms linked to enhanced renal tubular Na(+) reabsorption. Recently we demonstrated that Ca(2+) signaling is augmented in freshly isolated mesenteric artery myocytes from MHS rats. This is associated with greatly enhanced expression of Na(+)/Ca(2+) exchanger-1 (NCX1), C-type transient receptor potential (TRPC6) protein, and sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2) compared with arteries from Milan normotensive strain (MNS) rats.

How NaCl raises blood pressure: a new paradigm for the pathogenesis of salt-dependent hypertension.

Excess dietary salt is a major cause of hypertension. Nevertheless, the specific mechanisms by which salt increases arterial constriction and peripheral vascular resistance, and thereby raises blood pressure (BP), are poorly understood. Here we summarize recent evidence that defines specific molecular links between Na(+) and the elevated vascular resistance that directly produces high BP.

Gender differences in myogenic regulation along the vascular tree of the gerbil cochlea.

Regulation of cochlear blood flow is critical for hearing due to its exquisite sensitivity to ischemia and oxidative stress. Many forms of hearing loss such as sensorineural hearing loss and presbyacusis may involve or be aggravated by blood flow disorders. Animal experiments and clinical outcomes further suggest that there is a gender preference in hearing loss, with males being more susceptible.

Endothelial dysfunction in rat mesenteric artery after regional cardiac ischaemia-reperfusion.

In most previous studies, ischaemia-reperfusion (I/R)-induced vascular injury referred to injury in the tissue or blood vessel that was directly subjected to I/R. However, less attention has been focused on remote vascular injury that might be caused by cardiac I/R. In the present study, we aimed to assess whether cardiac I/R could affect vasoconstriction and vasodilatation in mesenteric arteries from Sprague-Dawley rats.

Exercise improves the dilatation function of mesenteric arteries in postmyocardial infarction rats via a PI3K/Akt/eNOS pathway-mediated mechanism.

Myocardial infarction (MI) has been shown to induce endothelial dysfunction in peripheral resistance arteries and thus increase peripheral resistance. This study was designed to investigate the underlying mechanisms of post-MI-related dysfunctional dilatation of peripheral resistance arteries and, furthermore, to examine whether exercise may restore dysfunctional dilatation of peripheral resistance arteries. Adult male Sprague-Dawley rats were divided into three groups: sham-operated, MI, and MI + exercise.

Tumor necrosis factor-α enhances microvascular tone and reduces blood flow in the cochlea via enhanced sphingosine-1-phosphate signaling.

Background And Purpose: We sought to demonstrate that tumor necrosis factor (TNF)-α, via sphingosine-1-phosphate signaling, has the potential to alter cochlear blood flow and thus, cause ischemic hearing loss.

Methods: We performed intravital fluorescence microscopy to measure blood flow and capillary diameter in anesthetized guinea pigs. To measure capillary diameter ex vivo, capillary beds from the gerbil spiral ligament were isolated from the cochlear lateral wall and maintained in an organ bath.

In vivo assessment of artery smooth muscle [Ca2+]i and MLCK activation in FRET-based biosensor mice.

The cellular mechanisms that control arterial diameter in vivo, particularly in hypertension, are uncertain. Here, we report a method that permits arterial intracellular Ca(2+) concentration ([Ca(2+)](i)), myosin light-chain kinase (MLCK) activation, and artery external diameter to be recorded simultaneously with arterial blood pressure (BP) in living mice under 1.5% isofluorane anesthesia.

Sympathetic nerves and the endothelium influence the vasoconstrictor effect of low concentrations of ouabain in pressurized small arteries.

We hypothesized that in salt-dependent forms of hypertension, endogenous ouabain acts on arterial smooth muscle to cause enhanced vasoconstriction. Here, we tested for the involvement of the arterial endothelium and perivascular sympathetic nerve terminals in ouabain-induced vasoconstriction. Segments of rat mesenteric or renal interlobar arteries were pressurized to 70 mmHg at 37 degrees C and exposed to ouabain (10(-11)-10(-7) M).

Knockout of Na+/Ca2+ exchanger in smooth muscle attenuates vasoconstriction and L-type Ca2+ channel current and lowers blood pressure.

Mice with smooth muscle (SM)-specific knockout of Na(+)/Ca(2+) exchanger type-1 (NCX1(SM-/-)) and the NCX inhibitor, SEA0400, were used to study the physiological role of NCX1 in mouse mesenteric arteries. NCX1 protein expression was greatly reduced in arteries from NCX1(SM-/-) mice generated with Cre recombinase. Mean blood pressure (BP) was 6-10 mmHg lower in NCX1(SM-/-) mice than in wild-type (WT) controls.

Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance.

Prolonged ouabain administration to normal rats causes sustained blood pressure (BP) elevation. This ouabain-induced hypertension (OH) has been attributed, in part, to the narrowing of third-order resistance arteries (approximately 320 microm internal diameter) as a result of collagen deposition in the artery media. Here we describe the structural and functional properties of fourth-order mesenteric small arteries from control and OH rats, including the effect of low-dose ouabain on myogenic tone in these arteries.

Role of store-operated Ca(2+) entry in adenosine-induced vasodilatation of rat small mesenteric artery.

Store-operated Ca(2+) entry (SOCE) has recently been proposed to contribute to Ca(2+) influx in vascular smooth muscle cells (VSMCs). Adenosine is known for its protective role against hypoxia and ischemia by increasing nutrient and oxygen supply through vasodilation. This study was designed to examine the hypothesis that SOCE have a functional role in adenosine-induced vasodilation.