Advanced glycated end-products inhibit dilation through constitutive endothelial RAGE and Nox1/4 in rat isolated skeletal muscle arteries.

Objective: This study investigated the actions of advanced glycated end-products (AGE), their receptors (RAGE), and NAD(P)H oxidase (Nox) subtypes 1, 2, and 4 on mechanisms of endothelium-dependent dilation of the rat cremaster muscle artery (CMA).

Methods: Immunofluorescence studies were used to examine expression of RAGE in rat arteries. ROS accumulation was measured using luminescence and fluorescence assays.

Effect of β /β -adrenoceptor blockade on β -adrenoceptor activity in the rat cremaster muscle artery.

Background And Purpose: The physiological role of vascular β -adrenoceptors is not fully understood. Recent evidence suggests cardiac β -adrenoceptors are functionally effective after down-regulation of β /β -adrenoceptors. The functional interaction between the β -adrenoceptor and other β-adrenoceptor subtypes in rat striated muscle arteries was investigated.

Agonist-evoked endothelial Ca signalling microdomains.

Localized, oscillating Ca signals have been identified in discrete microdomains of vascular endothelial cells. At myoendothelial contacts (between endothelial and smooth muscle cells), both endothelial Ca pulsars (IP-mediated release of intracellular Ca) and Ca sparklets (extracellular Ca entry via TRP channels) contribute to endothelium-dependent hyperpolarization of smooth muscle, vasodilation, and feedback control of vasoconstriction. Ca sparklets occurring at close-contact domains between endothelial cells are possibly involved in conducted hyperpolarization and spreading vasodilation in arterial networks.

Transient receptor potential canonical type 3 channels: Interactions, role and relevance - A vascular focus.

Transient receptor potential canonical type 3 channels (TRPC3) are expressed in neural, cardiac, respiratory and vascular tissues, with both similarities and differences between human and animal models for the same cell types. In common with all members of the six subfamilies of TRP channels, TRPC3 are non-voltage gated, non-selective cation channels that are mainly permeated by Ca, and have distinct molecular, biophysical, anatomical and functional properties. TRP channels are present in excitable and non-excitable cells where they sense and respond to a wide variety of physical and chemical stimuli.

TRPV3 expression and vasodilator function in isolated uterine radial arteries from non-pregnant and pregnant rats.

This study investigated the expression and function of transient receptor potential vanilloid type-3 ion channels (TRPV3) in uterine radial arteries isolated from non-pregnant and twenty-day pregnant rats. Immunohistochemistry (IHC) suggested TRPV3 is primarily localized to the smooth muscle in arteries from both non-pregnant and pregnant rats. IHC using C' targeted antibody, and qPCR of TRPV3 mRNA, suggested pregnancy increased arterial TRPV3 expression.

Activation of endothelial IKCa channels underlies NO-dependent myoendothelial feedback.

Agonist-induced vasoconstriction triggers a negative feedback response whereby movement of charged ions through gap junctions and/or release of endothelium-derived (NO) limit further reductions in diameter, a mechanism termed myoendothelial feedback. Recent studies indicate that electrical myoendothelial feedback can be accounted for by flux of inositol trisphosphate (IP3) through myoendothelial gap junctions resulting in localized increases in endothelial Ca(2+) to activate intermediate conductance calcium-activated potassium (IKCa) channels, the resultant hyperpolarization then conducting back to the smooth muscle to attenuate agonist-induced depolarization and tone. In the present study we tested the hypothesis that activation of IKCa channels underlies NO-mediated myoendothelial feedback.

Regulator of G protein signaling 5 is a determinant of gestational hypertension and preeclampsia.

Preeclampsia is a systemic vascular disorder of pregnancy and is associated with increased sensitivity to angiotensin II (AngII) and hypertension. The cause of preeclampsia remains unknown. We identified the role of regulator of G protein (heterotrimeric guanine nucleotide-binding protein) signaling 5 (RGS5) in blood pressure regulation during pregnancy and preeclampsia.

Effect of diet-induced obesity on BK(Ca) function in contraction and dilation of rat isolated middle cerebral artery.

This study examined the effect of diet-induced obesity on the functional role of large-conductance Ca²⁺-activated K⁺ channels (BK(Ca)) in rat middle cerebral arteries. Male Sprague-Dawley rats were fed a control (chow) or high-fat diet for 16-20 weeks. Diet-induced obesity decreased maximum bradykinin-induced dilation of isolated, pressurized (80 mmHg) arteries, but vasodilation induced by sodium nitroprusside (SNP) was unaltered.

Pregnancy-induced remodelling and enhanced endothelium-derived hyperpolarization-type vasodilator activity in rat uterine radial artery: transient receptor potential vanilloid type 4 channels, caveolae and myoendothelial gap junctions.

In pregnancy, the vasculature of the uterus undergoes rapid remodelling to increase blood flow and maintain perfusion to the fetus. The present study determines the distribution and density of caveolae, transient receptor potential vanilloid type 4 channels (TRPV4) and myoendothelial gap junctions, and the relative contribution of related endothelium-dependent vasodilator components in uterine radial arteries of control virgin non-pregnant and 20-day late-pregnant rats. The hypothesis examined is that specific components of endothelium-dependent vasodilator mechanisms are altered in pregnancy-related uterine radial artery remodelling.

Enhanced contractility in pregnancy is associated with augmented TRPC3, L-type, and T-type voltage-dependent calcium channel function in rat uterine radial artery.

In pregnancy, α-adrenoceptor-mediated vasoconstriction is augmented in uterine radial arteries and is accompanied by underlying changes in smooth muscle (SM) Ca(2+) activity. This study aims to determine the Ca(2+) entry channels associated with altered vasoconstriction in pregnancy, with the hypothesis that augmented vasoconstriction involves transient receptor potential canonical type-3 (TRPC3) and L- and T-type voltage-dependent Ca(2+) channels. Immunohistochemistry showed TRPC3, L-type Cav1.

Endothelial control of vasodilation: integration of myoendothelial microdomain signalling and modulation by epoxyeicosatrienoic acids.

Endothelium-derived epoxyeicosatrienoic acids (EETs) are fatty acid epoxides that play an important role in the control of vascular tone in selected coronary, renal, carotid, cerebral and skeletal muscle arteries. Vasodilation due to endothelium-dependent smooth muscle hyperpolarization (EDH) has been suggested to involve EETs as a transferable endothelium-derived hyperpolarizing factor. However, this activity may also be due to EETs interacting with the components of other primary EDH-mediated vasodilator mechanisms.

Advanced glycation end products acutely impair ca(2+) signaling in bovine aortic endothelial cells.

Post-translational modification of proteins in diabetes, including formation of advanced glycation end products (AGEs) are believed to contribute to vascular dysfunction and disease. Impaired function of the endothelium is an early indicator of vascular dysfunction in diabetes and as many endothelial cell processes are dependent upon intracellular [Ca(2+)] and Ca(2+) signaling, the aim of this study was to examine the acute effects of AGEs on Ca(2+) signaling in bovine aortic endothelial cells (BAEC). Ca(2+) signaling was studied using the fluorescent indicator dye Fura-2-AM.

Increased caveolae density and caveolin-1 expression accompany impaired NO-mediated vasorelaxation in diet-induced obesity.

Diet-induced obesity induces changes in mechanisms that are essential for the regulation of normal artery function, and in particular the function of the vascular endothelium. Using a rodent model that reflects the characteristics of human dietary obesity, in the rat saphenous artery we have previously demonstrated that endothelium-dependent vasodilation shifts from an entirely nitric oxide (NO)-mediated mechanism to one involving upregulation of myoendothelial gap junctions and intermediate conductance calcium-activated potassium channel activity and expression. This study investigates the changes in NO-mediated mechanisms that accompany this shift.

Transient receptor potential canonical type 3 channels facilitate endothelium-derived hyperpolarization-mediated resistance artery vasodilator activity.

Aims: Microdomain signalling mechanisms underlie key aspects of artery function and the modulation of intracellular calcium, with transient receptor potential (TRP) channels playing an integral role. This study determines the distribution and role of TRP canonical type 3 (C3) channels in the control of endothelium-derived hyperpolarization (EDH)-mediated vasodilator tone in rat mesenteric artery.

Methods And Results: TRPC3 antibody specificity was verified using rat tissue, human embryonic kidney (HEK)-293 cells stably transfected with mouse TRPC3 cDNA, and TRPC3 knock-out (KO) mouse tissue using western blotting and confocal and ultrastructural immunohistochemistry.

Dietary obesity increases NO and inhibits BKCa-mediated, endothelium-dependent dilation in rat cremaster muscle artery: association with caveolins and caveolae.

Obesity is a risk factor for hypertension and other vascular disease. The aim of this study was to examine the effect of diet-induced obesity on endothelium-dependent dilation of rat cremaster muscle arterioles. Male Sprague-Dawley rats (213 ± 1 g) were fed a cafeteria-style high-fat or control diet for 16-20 wk.

Calcium and endothelium-mediated vasodilator signaling.

Vascular tone refers to the balance between arterial constrictor and dilator activity. The mechanisms that underlie tone are critical for the control of haemodynamics and matching circulatory needs with metabolism, and thus alterations in tone are a primary factor for vascular disease etiology. The dynamic spatiotemporal control of intracellular Ca(2+) levels in arterial endothelial and smooth muscle cells facilitates the modulation of multiple vascular signaling pathways.

Myoendothelial contacts, gap junctions, and microdomains: anatomical links to function?

In several species and in many vascular beds, ultrastructural studies describe close contact sites between the endothelium and smooth muscle of <∼20nm. Such sites are thought to facilitate the local action of signaling molecules and/or the passage of current, as metabolic and electrical coupling conduits between the arterial endothelium and smooth muscle. These sites have the potential for bidirectional communication between the endothelium and smooth muscle, as a key pathway for coordinating vascular function.

Differential effects of diet-induced obesity on BKCa {beta}1-subunit expression and function in rat skeletal muscle arterioles and small cerebral arteries.

Mechanisms underlying obesity-related vascular dysfunction are unclear. This study examined the effect of diet-induced obesity on expression and function of large conductance Ca(2+)-activated potassium channel (BK(Ca)) in rat pressurized small resistance vessels with myogenic tone. Male Sprague-Dawley rats fed a cafeteria-style high fat diet (HFD; ∼30% energy from fat) for 16-20 wk were ∼30% heavier than controls fed standard chow (∼13% fat).

Endothelium-dependent vasodilation in human mesenteric artery is primarily mediated by myoendothelial gap junctions intermediate conductance calcium-activated K+ channel and nitric oxide.

Myoendothelial microdomain signaling via localized calcium-activated potassium channel (K(Ca)) and gap junction connexins (Cx) is critical for endothelium-dependent vasodilation in rat mesenteric artery. The present study determines the relative contribution of NO and gap junction-K(Ca) mediated microdomain signaling to endothelium-dependent vasodilation in human mesenteric artery. The hypothesis tested was that such activity is due to NO and localized K(Ca) and Cx activity.

Endothelium-dependent vasodilation in myogenically active mouse skeletal muscle arterioles: role of EDH and K(+) channels.

As smooth muscle cell (SMC) membrane potential (E(m)) is critical for vascular responsiveness, and arteriolar SMCs are depolarized at physiological intraluminal pressures, we hypothesized that myogenic tone impacts on dilation mediated by endothelium-derived hyperpolarization (EDH). Studies were performed on cannulated mouse cremaster arterioles [diameter, 33+/-2 microm (n=23) at 60 mmHg; SMC Em -34.6+/-1.

Heterogeneity in function of small artery smooth muscle BKCa: involvement of the beta1-subunit.

Arteriolar myogenic vasoconstriction occurs when increased stretch or membrane tension leads to smooth muscle cell depolarization and opening of voltage-gated Ca2+ channels. To prevent positive feedback and excessive pressure-induced vasoconstriction, studies in cerebral artery smooth muscle have suggested that activation of large conductance, Ca2+-activated K+ channels (BKCa) provides an opposing hyperpolarizing influence reducing Ca2+ channel activity. We have hypothesized that this mechanism may not equally apply to all vascular beds.

Membrane cholesterol depletion with beta-cyclodextrin impairs pressure-induced contraction and calcium signalling in isolated skeletal muscle arterioles.

Objective: Given evidence for clustering of signalling molecules and ion channels in cholesterol-rich membrane domains, the involvement of such structures in arteriolar smooth muscle mechanotransduction was examined.

Method: To determine the contribution of smooth muscle cholesterol-rich membrane domains to the myogenic response, isolated arterioles were exposed to the cholesterol-depleting agent beta-cyclodextrin (1-10 mM) in the absence and presence of excess exogenous cholesterol.

Results: beta-Cyclodextrin significantly impaired pressure-induced vasoconstriction, while excess cholesterol attenuated this effect.

Arteriolar myogenic signalling mechanisms: Implications for local vascular function.

Arterioles typically exist in a state of partial constriction that is related to the level of intraluminal pressure. This vasomotor response is a function of the vascular smooth muscle and occurs independently of neurohumoral and endothelial input. The physiological relevance of myogenic constriction relates to the setting of peripheral resistance, provision of a level of tone that vasodilators can access, and a contribution to control of capillary pressure.