Calcium dynamics in vascular smooth muscle

Primary Hyperparathyroidism and Pulmonary Embolism in Patients With a Fractured Neck of Femur

Two patients aged 82 and 77, with a fractured neck of the femur, were found to have primary hyperparathyroidism, characterized by hypercalcemia and hypercalciuria. Post-surgery, both developed pulmonary embolism (PE), highlighting a possible link between hypercalcemia and increased hypercoagulation risk. There have been few case reports suggesting the association between hypercalcemia due to hyperparathyroidism and the increase in tendency of hypercoagulation and subsequent risk of venous thromboembolism (VTE). This case series offers insights into how ionized calcium influences thrombin formation, platelet activation and aggregation, and activation of clotting factors such as factor VII and factor X, raising questions about the role of chronic hypercalcemia in VTE. Further research is needed to 1) establish whether chronic hypercalcemia in the absence of fracture can modulate the risk of hypercoagulation; 2) determine whether chronic hypercalcemia in individuals with bone fracture may represent a significantly higher hypercoagulability risk during the postoperative periods.

Effect of Torilis japonica Fruit Extract for Endothelium-Independent Vasorelaxation and Blood Pressure Lowering in Rats

Torilis japonica (TJ) fruit, is a herb that is traditionally used for erectile dysfunction (ED). Given the shared mechanisms of ED and hypertension through vascular smooth muscle, we hypothesized that TJ would be effective in vasodilation and blood pressure reduction. This study confirmed the authenticity of TJ samples via DNA barcoding and quantified the main active compound, torilin, using HPLC. TJ was extracted with distilled water (TJW) and 50% ethanol (TJE), yielding torilin contents of 0.35 ± 0.01% and 2.84 ± 0.02%, respectively. Ex vivo tests on thoracic aortic rings from Sprague-Dawley rats showed that TJE (3-300 µg/mL) induced endothelium-independent, concentration-dependent vasodilation, unlike TJW. Torilin caused concentration-dependent relaxation with an EC50 of 210 ± 1.07 µM. TJE's effects were blocked by a voltage-dependent K+ channel blocker and alleviated contractions induced by CaCl2 and angiotensin II. TJE inhibited vascular contraction induced by phenylephrine or KCl via extracellular CaCl2 and enhanced inhibition with nifedipine, indicating involvement of voltage-dependent and receptor-operated Ca2+ channels. Oral administration of TJE (1000 mg/kg) significantly reduced blood pressure in spontaneously hypertensive rats. These findings suggest TJ extract's potential for hypertension treatment through vasorelaxant mechanisms, though further research is needed to confirm its efficacy and safety.

The incidence of admission ionised hypocalcaemia in paediatric major trauma-A systematic review and meta-analysis

OBJECTIVES

In adult major trauma patients admission hypocalcaemia occurs in approximately half of cases and is associated with increased mortality. However, data amongst paediatric patients are limited. The objectives of this review were to determine the incidence of admission ionised hypocalcaemia in paediatric major trauma patients and to explore whether hypocalcaemia is associated with adverse outcomes.

METHODS

A systematic review was conducted following PRISMA guidelines. All studies including major trauma patients <18 years old, with an ionised calcium concentration obtained in the Emergency Department (ED) prior to the receipt of blood products in the ED were included. The primary outcome was incidence of ionised hypocalcaemia. Random-effects Sidik-Jonkman modelling was executed for meta-analysis of mortality and pH difference between hypo- and normocalcaemia, Odds ratio (OR) was the reporting metric for mortality. The reporting metric for the continuous variable of pH difference was Glass' D (a standardized difference). Results are reported with 95% confidence intervals (CIs) and significance was defined as p <0.05.

RESULTS

Three retrospective cohort studies were included. Admission ionised hypocalcaemia definitions ranged from <1.00 mmol/l to <1.16 mmol/l with an overall incidence of 112/710 (15.8%). For mortality, modelling with low heterogeneity (I2 39%, Cochrane's Q p = 0.294) identified a non-significant (p = 0.122) estimate of hypocalcaemia increasing mortality (pooled OR 2.26, 95% CI 0.80-6.39). For the pH difference, meta-analysis supported generation of a pooled effect estimate (I2 57%, Cochrane's Q p = 0.100). The effect estimate of the mean pH difference was not significantly different from null (p = 0.657), with the estimated pH slightly lower in hypocalcaemia (Glass D standardized mean difference -0.08, 95% CI -0.43 to 0.27).

CONCLUSION

Admission ionised hypocalcaemia was present in at least one in six paediatric major trauma patients. Ionised hypocalcaemia was not identified to have a statistically significant association with mortality or pH difference.

A Lifelike guided journey through the pathophysiology of pulmonary hypertension-from measured metabolites to the mechanism of action of drugs

Introduction

Pulmonary hypertension (PH) is a pathological condition that affects approximately 1% of the population. The prognosis for many patients is poor, even after treatment. Our knowledge about the pathophysiological mechanisms that cause or are involved in the progression of PH is incomplete. Additionally, the mechanism of action of many drugs used to treat pulmonary hypertension, including sotatercept, requires elucidation.

Methods

Using our graph-powered knowledge mining software Lifelike in combination with a very small patient metabolite data set, we demonstrate how we derive detailed mechanistic hypotheses on the mechanisms of PH pathophysiology and clinical drugs.

Results

In PH patients, the concentration of hypoxanthine, 12(S)-HETE, glutamic acid, and sphingosine 1 phosphate is significantly higher, while the concentration of L-arginine and L-histidine is lower than in healthy controls. Using the graph-based data analysis, gene ontology, and semantic association capabilities of Lifelike, led us to connect the differentially expressed metabolites with G-protein signaling and SRC. Then, we associated SRC with IL6 signaling. Subsequently, we found associations that connect SRC, and IL6 to activin and BMP signaling. Lastly, we analyzed the mechanisms of action of several existing and novel pharmacological treatments for PH. Lifelike elucidated the interplay between G-protein, IL6, activin, and BMP signaling. Those pathways regulate hallmark pathophysiological processes of PH, including vasoconstriction, endothelial barrier function, cell proliferation, and apoptosis.

Discussion

The results highlight the importance of SRC, ERK1, AKT, and MLC activity in PH. The molecular pathways affected by existing and novel treatments for PH also converge on these molecules. Importantly, sotatercept affects SRC, ERK1, AKT, and MLC simultaneously. The present study shows the power of mining knowledge graphs using Lifelike's diverse set of data analytics functionalities for developing knowledge-driven hypotheses on PH pathophysiological and drug mechanisms and their interactions. We believe that Lifelike and our presented approach will be valuable for future mechanistic studies of PH, other diseases, and drugs.

Tissue-specific Cre driver mice to study vascular diseases

Vascular diseases, including atherosclerosis and abdominal aneurysms, are the primary cause of mortality and morbidity among the elderly worldwide. The life quality of patients is significantly compromised due to inadequate therapeutic approaches and limited drug targets. To expand our comprehension of vascular diseases, gene knockout (KO) mice, especially conditional knockout (cKO) mice, are widely used for investigating gene function and mechanisms of action. The Cre-loxP system is the most common method for generating cKO mice. Numerous Cre driver mice have been established to study the main cell types that compose blood vessels, including endothelial cells, smooth muscle cells, and fibroblasts. Here, we first discuss the characteristics of each layer of the arterial wall. Next, we provide an overview of the representative Cre driver mice utilized for each of the major cell types in the vessel wall and their most recent applications in vascular biology. We then go over Cre toxicity and discuss the practical methods for minimizing Cre interference in experimental outcomes. Finally, we look into the future of tissue-specific Cre drivers by introducing the revolutionary single-cell RNA sequencing and dual recombinase system.

Vascular dysfunction caused by loss of Brn-3b/POU4F2 transcription factor in aortic vascular smooth muscle cells is linked to deregulation of calcium signalling pathways

Phenotypic and functional changes in vascular smooth muscle cells (VSMCs) contribute significantly to cardiovascular diseases (CVD) but factors driving early adverse vascular changes are poorly understood. We report on novel and important roles for the Brn-3b/POU4F2 (Brn-3b) transcription factor (TF) in controlling VSMC integrity and function. Brn-3b protein is expressed in mouse aorta with localisation to VSMCs. Male Brn-3b knock-out (KO) aortas displayed extensive remodelling with increased extracellular matrix (ECM) deposition, elastin fibre disruption and small but consistent narrowing/coarctation in the descending aortas. RNA sequencing analysis showed that these effects were linked to deregulation of genes required for calcium (Ca2+) signalling, vascular contractility, sarco-endoplasmic reticulum (S/ER) stress responses and immune function in Brn-3b KO aortas and validation studies confirmed changes in Ca2+ signalling genes linked to increased intracellular Ca2+ and S/ER Ca2+ depletion [e.g. increased, Cacna1d Ca2+ channels; ryanodine receptor 2, (RyR2) and phospholamban (PLN) but reduced ATP2a1, encoding SERCA1 pump] and chaperone proteins, Hspb1, HspA8, DnaJa1 linked to increased S/ER stress, which also contributes to contractile dysfunction. Accordingly, vascular rings from Brn-3b KO aortas displayed attenuated contractility in response to KCl or phenylephrine (PE) while Brn-3b KO-derived VSMC displayed abnormal Ca2+ signalling following ATP stimulation. This data suggests that Brn-3b target genes are necessary to maintain vascular integrity /contractile function and deregulation upon loss of Brn-3b will contribute to contractile dysfunction linked to CVD.

CaV3.1 channels facilitate calcium wave generation and myogenic tone development in mouse mesenteric arteries

The arterial myogenic response to intraluminal pressure elicits constriction to maintain tissue perfusion. Smooth muscle [Ca2+] is a key determinant of constriction, tied to L-type (CaV1.2) Ca2+ channels. While important, other Ca2+ channels, particularly T-type could contribute to pressure regulation within defined voltage ranges. This study examined the role of one T-type Ca2+ channel (CaV3.1) using C57BL/6 wild type and CaV3.1-/- mice. Patch-clamp electrophysiology, pressure myography, blood pressure and Ca2+ imaging defined the CaV3.1-/- phenotype relative to C57BL/6. CaV3.1-/- mice had absent CaV3.1 expression and whole-cell current, coinciding with lower blood pressure and reduced mesenteric artery myogenic tone, particularly at lower pressures (20-60 mmHg) where membrane potential is hyperpolarized. This reduction coincided with diminished Ca2+ wave generation, asynchronous events of Ca2+ release from the sarcoplasmic reticulum, insensitive to L-type Ca2+ channel blockade (Nifedipine, 0.3 µM). Proximity ligation assay (PLA) confirmed IP3R1/CaV3.1 close physical association. IP3R blockade (2-APB, 50 µM or xestospongin C, 3 µM) in nifedipine-treated C57BL/6 arteries rendered a CaV3.1-/- contractile phenotype. Findings indicate that Ca2+ influx through CaV3.1 contributes to myogenic tone at hyperpolarized voltages through Ca2+-induced Ca2+ release tied to the sarcoplasmic reticulum. This study helps establish CaV3.1 as a potential therapeutic target to control blood pressure.

Primary Failure Eruption: Genetic Investigation, Diagnosis and Treatment: A Systematic Review

AIM

The aim of this systematic review is to explore the pathology, diagnosis, treatment, and genetic basis of Primary Failure of Eruption (PFE) in the field of pediatric dentistry and orthodontics.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed for this review. The databases PubMed, Science Direct, Scopus, and Web of Science were searched from 1 July 2013 to 1 July 2023, using keywords "primary failure of tooth eruption" OR "primary failure of eruption" OR "tooth eruption failure" OR "PFE" AND "orthodontics". The study selection process involved screening articles based on the inclusion and exclusion criteria.

RESULTS

A total of 1151 results were obtained from the database search, with 14 papers meeting the inclusion criteria. The review covers various aspects of PFE, including its clinical features, diagnosis, treatment options, and genetic associations with mutations in the PTH1R gene. Differentiation between PFE and Mechanical Failure of Eruption (MFE) is crucial for accurate treatment planning. Orthodontic and surgical interventions, along with multidisciplinary approaches, have been employed to manage PFE cases. Genetic testing for PTH1R mutations plays a significant role in confirming the diagnosis and guiding treatment decisions, although some cases may not be linked to this mutation.

CONCLUSIONS

This systematic review provides valuable insights into the diagnosis, treatment, and genetic basis of PFE. Early diagnosis and personalized treatment planning are crucial for successful management. Genetic testing for PTH1R mutations aids in accurate diagnosis and may influence treatment decisions. However, further research is needed to explore the complex genetic basis of PFE fully and improve treatment outcomes for affected individuals.

Redox Metabolism and Vascular Calcification in Chronic Kidney Disease

Vascular calcification (VC) is a common complication in patients with chronic kidney disease which increases their mortality. Although oxidative stress is involved in the onset and progression of this disorder, the specific role of some of the main redox regulators, such as catalase, the main scavenger of H2O2, remains unclear. In the present study, epigastric arteries of kidney transplant recipients, a rat model of VC, and an in vitro model of VC exhibiting catalase (Cts) overexpression were analysed. Pericalcified areas of human epigastric arteries had increased levels of catalase and cytoplasmic, rather than nuclear runt-related transcription factor 2 (RUNX2). In the rat model, advanced aortic VC concurred with lower levels of the H2O2-scavenger glutathione peroxidase 3 compared to controls. In an early model of calcification using vascular smooth muscle cells (VSMCs), Cts VSMCs showed the expected increase in total levels of RUNX2. However, Cts VMSCs also exhibited a lower percentage of the nucleus stained for RUNX2 in response to calcifying media. In this early model of VC, we did not observe a dysregulation of the mitochondrial redox state; instead, an increase in the general redox state was observed in the cytoplasm. These results highlight the complex role of antioxidant enzymes as catalase by regulation of RUNX2 subcellular location delaying the onset of VC.

Vasorelaxant effect of Alpinia zerumbet's essential oil on rat resistance artery involves blocking of calcium mobilization

Alpinia zerumbet is a plant from the Zingiberaceae family, popularly used for hypertension treatment. Several studies have demonstrated Alpinia zerumbet vasodilator effect on conductance vessels but not on resistance vessels. Thereby, the aim of this study was to verify the vasodilator effect of the essential oil of Alpinia zerumbet (EOAz) on isolated rat resistance arteries and characterize its mechanism of action. Therefore, the effect of EOAz (3 to 3000 μg/mL) was verified in second-order branches of the mesenteric artery (SOBMA) pre-contracted by KCl and U46619. To study the mechanism of action, the influence of several inhibitors (TEA, 4-AP, Glibenclamide, Atropine, L-NAME, ODQ and indomethacin) on the vasodilator effect of EOAz was evaluated. Some protocols were also performed aiming to study the effect of EOAz on Ca2+ influx and release from intracellular storage. Furthermore, the binding energy of the main constituents with calcium channels were evaluated by molecular docking. Results showed an endothelium-independent vasorelaxant effect of EOAz on SOBMA, and only ODQ and L-NAME produced significant alteration on its pEC50. Regarding the calcium assays, contraction reduction caused by incubation with EOAz was observed in all three protocols. Hence, our results suggest that EOAz has a vasodilator effect mediated by inhibition of Ca2+ influx and release from intracellular storage, as well as an activation of the NOS/sGC pathway.

Interactions between Mediterranean Diet Supplemented with Dairy Foods and the Gut Microbiota Influence Cardiovascular Health in an Australian Population

The impact of a Mediterranean diet on the intestinal microbiome has been linked to its health benefits. We aim to evaluate the effects of a Mediterranean diet supplemented with dairy foods on the gut microbiome in Australians at risk of cardiovascular disease. In a randomised controlled cross-over study, 34 adults with a systolic blood pressure ≥120 mmHg and with risk factors for cardiovascular disease were randomly allocated to a Mediterranean diet with 3-4 daily serves of dairy foods (Australian recommended daily intake (RDI) of 1000-1300 mg per day (MedDairy)) or a low-fat (LFD) control diet. Between each 8-week diet, participants underwent an 8-week washout period. Microbiota characteristics of stool samples collected at the start and end of each diet period were determined by 16S rRNA amplicon sequencing. MedDairy-associated effects on bacterial relative abundance were correlated with clinical, anthropometric, and cognitive outcomes. No change in the overall faecal microbial structure or composition was observed with either diet (p > 0.05). The MedDairy diet was associated with changes in the relative abundance of several bacterial taxa, including an increase in Butyricicoccus and a decrease in Colinsella and Veillonella (p < 0.05). Increases in Butyricicoccus relative abundance over 8 weeks were inversely correlated with lower systolic blood pressure (r = -0.38, p = 0.026) and positively correlated with changes in fasting glucose levels (r = 0.39, p = 0.019), specifically for the MedDairy group. No significant associations were observed between the altered taxa and anthropometric or cognitive measures (p > 0.05). Compared to a low-fat control diet, the MedDairy diet resulted in changes in the abundance of specific gut bacteria, which were associated with clinical outcomes in adults at risk of CVD.

Diversity of cells and signals in the cardiovascular system

This white paper is the outcome of the seventh UC Davis Cardiovascular Research Symposium on Systems Approach to Understanding Cardiovascular Disease and Arrhythmia. This biannual meeting aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2022 Symposium was 'Cell Diversity in the Cardiovascular System, cell-autonomous and cell-cell signalling'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies, and challenges in examining cell and signal diversity, co-ordination and interrelationships involved in cardiovascular function. This paper originates from the topics of formal presentations and informal discussions from the Symposium, which aimed to develop a holistic view of how the multiple cell types in the cardiovascular system integrate to influence cardiovascular function, disease progression and therapeutic strategies. The first section describes the major cell types (e.g. cardiomyocytes, vascular smooth muscle and endothelial cells, fibroblasts, neurons, immune cells, etc.) and the signals involved in cardiovascular function. The second section emphasizes the complexity at the subcellular, cellular and system levels in the context of cardiovascular development, ageing and disease. Finally, the third section surveys the technological innovations that allow the interrogation of this diversity and advancing our understanding of the integrated cardiovascular function and dysfunction.

β3 Receptor Signaling in Pregnant Human Myometrium Suggests a Role for β3 Agonists as Tocolytics

Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. At the present time, nothing can reliably halt labor once it begins. The knowledge that agonists of the β2 adrenergic receptor relax airway smooth muscle and are effective in the treatment of asthma led to the notion that β2 mimetics would prevent preterm birth by relaxing uterine smooth muscle. The activation of cAMP-dependent protein kinase by β2 receptors is unable to provide meaningful tocolysis. The failure of β2 agonists such as ritodrine and terbutaline to prevent preterm birth suggests that the regulation of uterine smooth muscle is disparate from that of airway. Other smooth muscle quiescent-mediating molecules, such as nitric oxide, relax vascular smooth muscle in a cGMP-protein kinase G-dependent manner; however, nitric oxide activation of protein kinase G fails to explain the relaxation of the myometrium to nitric oxide. Moreover, nitric oxide-mediated relaxation is blunted in preterm labor, and thus, for this reason and because of the fall in maternal blood pressure, nitric oxide cannot be employed as a tocolytic. The β3 adrenergic receptor-mediated relaxation of the human myometrium is claimed to be cAMP-dependent protein kinase-dependent. This is scientifically displeasing given the failure of β2 agonists as tocolytics and suggests a non-canonical signaling role for β3AR in myometrium. The addition of the β3 agonist mirabegron to pregnant human myometrial strips in the tissue bath relaxes oxytocin-induced contractions. Mirabegron stimulates nitric oxide production in myometrial microvascular endothelial cells, and the relaxation of uterine tissue in vitro is partially blocked by the addition of the endothelial nitric oxide synthase blocker Nω-Nitro-L-arginine. Recent data suggest that both endothelial and smooth muscle cells respond to β3 stimulation and contribute to relaxation through disparate signaling pathways. The repurposing of approved medications such as mirabegron (Mybetriq™) tested in human myometrium as uterine tocolytics can advance the prevention of preterm birth.

Adverse effects of copper, manganese and mercury, alone and in mixtures on the aorta and heart of Spraque-Dawley rats

Cardiovascular diseases (CVD) are a common global cause of death and are therefore a major health concern. Inhaled or ingested environmental heavy metals contribute to the development of CVD. The aim of this study was to address the limited information available on the effect of relevant dosages of metals in mixtures. Three metals with reported effects on the cardiovascular system (CVS) were identified, and these metals were copper (Cu), manganese (Mn) and mercury (Hg). In Sprague-Dawley rats, the adverse effects of copper (Cu), manganese (Mn) and mercury (Hg), alone and as part of mixtures, on the blood parameters, the aorta and heart were investigated. Forty-eight male Sprague-Dawley rats were randomly divided into eight groups (n = 6): control, Cu, Mn, Hg, Cu + Mn, Cu + Hg, Mn + Hg and Cu, Mn + Hg. The seven experimental groups received the metal mixtures at 100 times the World Health Organisation (WHO) safety limit for drinking water (2 mg/L for Cu, 0.4 mg/L for Mn and 0.06 mg/L for Hg) via oral gavage for 28 days. After 28 days, compared with the control, red blood cell levels were increased for Cu + Hg. All other measured blood parameters were unchanged. Morphological changes in the tunica media were connective tissue deposition and an abundance of collagen type I in the metal exposed aortic tissues. In the cardiac tissue of metal-exposed rats, changes in the cardiomyocyte and myofibrillar arrangement, with an increase in collagen type I and III was observed. Ultrastructurally, the aortic collagen and elastin band arrangement and the cardiac mitochondrial and myofibrillar arrangement and structures were altered in the experimental groups. These changes indicated that exposure to these metals in rats caused minor changes in the blood parameters, however, the changes in tissue and cellular structure indicated an increased risk for the development of CVD.

MasR and pGCA receptor activation protects primary vascular smooth muscle cells and endothelial cells against oxidative stress via inhibition of intracellular calcium

Cardiovascular diseases (CVDs) are associated with vascular smooth muscle cell (VSMC) and endothelial cell (EC) damage. Angiotensin1-7 (Ang1-7) and B-type natriuretic peptide (BNP) are responsible for vasodilation and regulation of blood flow. These protective effects of BNP are primarily mediated by the activation of sGCs/cGMP/cGKI pathway. Conversely, Ang1-7 inhibits Angiotensin II-induced contraction and oxidative stress via Mas receptor activation. Thus, the aim of the study was to determine the effect of co-activation of MasR and particulate guanylate cyclase receptor (pGCA) pathways by synthesized novel peptide (NP) in oxidative stress-induced VSMCs and ECs. MTT and Griess reagent assay kits were used for the standardization of the oxidative stress (H₂ O₂ ) induced model in VSMCs. The expression of targeted receptors in VSMC was done by RT-PCR and Western blot analysis. Protective effect of NP in VSMC and EC was determined by immunocytochemistry, FACS analysis, and Western blot analysis. Underlying mechanisms of EC-dependent VSMC relaxation were done by determining downstream mRNA gene expression and intracellular calcium imaging of cells. Synthesized NP significantly improved oxidative stress-induced injury in VSMCs. Remarkably, the actions of NP were superior to that of the Ang1-7 and BNP alone. Further, a mechanistic study in VSMC and EC suggested the involvement of upstream mediators of calcium inhibition for the therapeutic effect. NP is reported to possess vascular protective activities and is also involved in the improvement of endothelial damage. Moreover, it is highly effective than that of individual peptides BNP and Ang1-7 and therefore it may represent a promising strategy for CVDs.

Novel identification and modulation of the mechanosensitive Piezo1 channel in human myometrium

Approximately 10% of US births deliver preterm before 37 weeks of completed gestation. Premature infants are at risk for life-long debilitating morbidities and death, and spontaneous preterm labour explains 50% of preterm births. In all cases existing treatments are ineffective, and none are FDA approved. The mechanisms that initiate preterm labour are not well understood but may result from dysfunctional regulation of quiescence mechanisms. Human pregnancy is accompanied by large increases in blood flow, and the uterus must enlarge by orders of magnitude to accommodate the growing fetus. This mechanical strain suggests that stretch-activated channels may constitute a mechanism to explain gestational quiescence. Here we identify for the first time that Piezo1, a mechanosensitive cation channel, is present in the uterine smooth muscle and microvascular endothelium of pregnant myometrium. Piezo is downregulated during preterm labour, and stimulation of myometrial Piezo1 in an organ bath with the agonist Yoda1 relaxes the tissue in a dose-dependent fashion. Further, stimulation of Piezo1 while inhibiting protein kinase A, AKT, or endothelial nitric oxide synthase mutes the negative inotropic effects of Piezo1 activation, intimating that actions on the myocyte and endothelial nitric oxide signalling contribute to Piezo1-mediated contractile dynamics. Taken together, these data highlight the importance of stretch-activated channels in pregnancy maintenance and parturition, and identify Piezo1 as a tocolytic target of interest. KEY POINTS: Spontaneous preterm labour is a serious obstetric dilemma without a known cause or effective treatments. Piezo1 is a stretch-activated channel important to muscle contractile dynamics. Piezo1 is present in the myometrium and is dysregulated in women who experience preterm labour. Activation of Piezo1 by the agonist Yoda1 relaxes the myometrium in a dose-dependent fashion, indicating that Piezo1 modulation may have therapeutic benefits to treat preterm labour.

Effect of Different Extraction Methods on Anthocyanin Content in Hibiscus sabdariffa L. and their Antiplatelet and Vasorelaxant Properties

Hibiscus sabdariffa L. is a worldwide component for tea and beverages, being a natural source of anthocyanins, which are associated with cardiovascular activities. To investigate this relationship, we explored different methods of aqueous extraction on the anthocyanin content and antioxidant activity of H. sabdariffa L. calyx extract (HSCE). Pharmacological effects via platelet aggregation, calcium mobilization, cyclic nucleotide levels, vasodilator-stimulated phosphoprotein Ser157 and Ser239, and on the vasomotor response of aortic rings isolated from mice are studied herewith. We found that the application of ultrasonic turbolization, 20 min, combined with acidified water was significantly more effective in the extraction process, providing extracts with the highest levels of anthocyanins (8.73 and 9.63 mg/100 g) and higher antioxidant activity (6.66 and 6.78 μM trolox/g of sample). HSCE significantly inhibited (100-1000 μg/mL) arachidonic acid-induced platelet aggregation, reduced calcium mobilization, and increased cAMP and cGMP levels with VASPSer157 and VASPSer239 phosphorylation. Vasorelaxation reduction was confirmed by the aortic rings and endothelium assays treated with nitric oxide synthase inhibitors, soluble guanylyl cyclase (sGC) oxidizing agent, or Ca²⁺-activated K⁺ channel inhibitor. The increasing of cGMP levels could be understood considering the sGC stimulation by HSCE compounds in the specific stimulus domain, which allows an understanding of the observed antiplatelet and vasorelaxant properties of H. sabdariffa L. calyx extract.

Dibazol-induced relaxation of ophthalmic artery in C57BL/6J mice is correlated with the potency to inhibit voltage-gated Ca2+ channels

We aimed to explore the effect of dibazol on the ophthalmic artery (OA) and ophthalmic artery smooth muscle cells (OASMCs) of C57BL/6J mice as well as the underlying mechanisms. The OA of C57BL/6J mice was isolated under a dissecting microscope for primary OASMCs culture and myogenic tests. OASMCs were identified through morphological and immunofluorescence analyses. Morphology changes in the OASMCs were examined by staining using rhodamine-phalloidin. We performed a collagen gel contraction assay to measure the contractile and relaxant activities of the OASMCs. The molecular probe Fluo-4 AM was used to examine intracellular free Ca²⁺ levels ([Ca²⁺]_in). The myogenic effects of OA were examined using wire myography. Additionally, the whole-cell patch-clamp technique was used to investigate the mechanisms underlying the relaxant effect of dibazol on L-type voltage-gated Ca²⁺ channels (LVGC) in isolated cells. 10^-5 M dibazol significantly inhibited the contraction of OASMCs and increased the [Ca²⁺]_in response to 30 mM KCl in a concentration-dependent manner. Dizabol had a more significant relaxant effect than 10^-5 M isosorbide dinitrate (ISDN). Similarly, dibazol showed a significant dose-dependent relaxant effect on OA contraction induced by 60 mM KCl or 0.3 μM 9,11-Dideoxy-9α,11α-methanoepoxy prostaglandin F_2α (U46619). The current-voltage (I-V) curve revealed that dibazol decreased Ca²⁺ currents in a concentration-dependent manner. In conclusion, dibazol exerted relaxant effects on the OA and OASMCs, which may involve the inhibition of the Ca²⁺ influx through LVGC in the cells.

Investigation of electrical stimulation on phenotypic vascular smooth muscle cells differentiation in tissue-engineered small-diameter vascular graft

In the development of vascular tissue engineering, particularly in the case of small diameter vessels, one of the key obstacles is the blockage of these veins once they enter the in vivo environment. One of the contributing factors to this problem is the aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) from the media layer of the artery to the interior of the channel. Two distinct phenotypes have been identified for smooth muscle cells, namely synthetic and contractile. Since the synthetic phenotype plays an essential role in the unusual growth and migration, the aim of this study was to convert the synthetic phenotype into the contractile one, which is a solution to prevent the abnormal growth of VSMCs. To achieve this goal, these cells were subjected to electrical signals, using a 1000 μA sinusoidal stimulation at 10 Hz for four days, with 20 min duration per 24 h. The morphological transformations and changes in the expression of vimentin, nestin, and β-actin proteins were then studied using ICC and flow cytometry assays. Also, the expression of VSMC specific markers such as smooth muscle myosin heavy chain (SMMHC) and smooth muscle alpha-actin (α-SMA) were evaluated using RT-PCR test. In the final phase of this study, the sheep decellularized vessel was employed as a scaffold for seeding these cells. Based on the results, electrical stimulation resulted in some morphological alterations in VSMCs. Furthermore, the observed reductions in the expression levels of vimentin, nestin and β-actin proteins and increase in the expression of SMMHC and α-SMA markers showed that it is possible to convert the synthetic phenotype to the contractile one using the studied regime of electrical stimulation. Finally, it can be concluded that electrical stimulation can significantly affect the phenotype of VSMCs, as demonstrated in this study.

MicroRNA-423-5p Mediates Cocaine-Induced Smooth Muscle Cell Contraction by Targeting Cacna2d2

Cocaine abuse increases the risk of atherosclerotic cardiovascular disease (CVD) and causes acute coronary syndromes (ACS) and hypertension (HTN). Significant research has explored the role of the sympathetic nervous system mediating the cocaine effects on the cardiovascular (CV) system. However, the response of the sympathetic nervous system alone is insufficient to completely account for the CV consequences seen in cocaine users. In this study, we examined the role of microRNAs (miRNAs) in mediating the effect of cocaine on the CV system. MiRNAs regulate many important biological processes and have been associated with both response to cocaine and CV disease development. Multiple miRNAs have altered expression in the CV system (CVS) upon cocaine exposure. To understand the molecular mechanisms underlying the cocaine response in the CV system, we studied the role of miRNA-423-5p and its target Cacna2d2 in the regulation of intracellular calcium concentration and SMC contractility, a critical factor in the modulation of blood pressure (BP). We used in vivo models to evaluate BP and aortic stiffness. In vitro, cocaine treatment decreased miR-423-5p expression and increased Cacna2d2 expression, which led to elevated intracellular calcium concentrations and increased SMC contractility. Overexpression of miR-423-5p, silencing of its target Cacna2d2, and treatment with a calcium channel blocker reversed the elevated SMC contractility caused by cocaine. In contrast, suppression of miR-423-5p increased the intracellular calcium concentration and SMC contractibility. In vivo, smooth muscle-specific overexpression of miR-423-5p ameliorated the increase in BP and aortic stiffness associated with cocaine use. Thus, miR-423-5p regulates SMC contraction by modulating Cacna2d2 expression increasing intracellular calcium concentrations. Modulation of the miR-423-5p-Cacna2d2-Calcium transport pathway may represent a novel therapeutic strategy to improve cocaine-induced HTN and aortic stiffness.

Relationship between blood calcium level and post-milking teat canal closure in dairy cows

The teat canal-one of the primary defense mechanisms of the udder-ensures the milk flow during milking in bovines and prevents pathogens from entering the udder by forming a barrier through the elastic muscle and keratin layers tightly closing the surrounding area. The current study investigated the effects of blood calcium status on teat closure in cows after milking. The study covered 200 healthy teats, of which 100 were from normocalcemic (NC) cows and 100 were from subclinical hypocalcemic (SCH) cows. Teat canal length (TCL) and width (TCW) were measured with ultrasonography at 0-min pre-milking and 15- and 30-min post-milking. Cylindrically shaped teat canal volume (TCV) was calculated by deriving from TCL and TCW. Time-dependent changes in teat canal closure and their relationships with blood calcium levels were analyzed. The results showed that the calcium level did not affect TCL, TCW, and TCV (P > 0.05) during the 15-min post-milking period. However, TCL (P < 0.001), TCW (P < 0.05), and TCV (P < 0.001) were lower in NC cows than in SCH cows at 30-min post-milking. At 15-min post-milking, no correlation existed between the teat canal closure (ΔTCL, ΔTCW, and ΔTCV) and the blood calcium level, while significant correlations were available between the teat canal closure and the blood calcium level {ΔTCL (r: - 0.288, P < 0.001), ΔTCW (r: - 0.260, P < 0.001), ΔTCV (r: - 0.150, P < 0.05)} at 30-min post-milking. The current study concluded that the blood calcium status significantly impacts the teat canal closure in bovines, and calcium status should be meticulously monitored with the mastitis control program to apply necessary strategic steps.

Chemo-mechanical modeling of smooth muscle cell activation for the simulation of arterial walls under changing blood pressure

In this paper, a novel chemo-mechanical model is proposed for the description of the stretch-dependent chemical processes known as Bayliss effect and their impact on the active contraction in vascular smooth muscle. These processes are responsible for the adaptive reaction of arterial walls to changing blood pressure by which the blood vessels actively support the heart in providing sufficient blood supply for varying demands in the supplied tissues. The model is designed to describe two different stretch-dependent mechanisms observed in smooth muscle cells (SMCs): a calcium-dependent and a calcium-independent contraction. For the first one, stretch of the SMCs leads to an inlet of calcium ions which activates the myosin light chain kinase (MLCK). The increased activity of MLCK triggers the contractile units of the cells resulting in the contraction on a comparatively short time scale. For the calcium-independent contraction mechanism, stretch-dependent receptors of the cell membrane stimulate an intracellular reaction leading to an inhibition of the antagonist of MLCK, the myosin light chain phosphatase resulting in a contraction on a comparatively long time scale. An algorithmic framework for the implementation of the model in finite element programs is derived. Based thereon, it is shown that the proposed approach agrees well with experimental data. Furthermore, the individual aspects of the model are analyzed in numerical simulations of idealized arteries subject to internal pressure waves with changing intensities. The simulations show that the proposed model is able to describe the experimentally observed contraction of the artery as a reaction to increased internal pressure, which can be considered a crucial aspect of the regulatory mechanism of muscular arteries.

The inhibitory effect of escitalopram on mouse detrusor contractility: The role of L-type calcium channels

Selective serotonin reuptake inhibitors (SSRIs) are associated with urinary problems attributed to their central effects. ESC is a preferred SSRI and several case reports described that ESC is related to urinary retention. However, the direct effect of ESC on detrusor contractility is still not completely elucidated. Thus, we investigated the effect of ESC on detrusor contractility and mechanism(s) of its action in isolated mouse detrusor strips. Molecular docking and measurement of intracellular calcium were performed to determine the possible calcium channel blocking effect of ESC. The contractile responses to carbachol (CCh), KCl and electrical field stimulation of detrusor strips were significantly abolished by ESC (10 or 100 μM). ESC relaxed KCl-precontracted detrusor strips concentration-dependently, which was not affected by tetraethylammonium, glibenclamide, 4-aminopyridine, propranolol, L-NAME or methylene blue. ESC (10 or 100 μM) reduced both the CaCl₂- and CCh-induced contractions under calcium-free conditions, indicating the role of calcium-involved mechanisms in ESC-mediated relaxation. Furthermore, ESC significantly decreased Bay K8644-induced contraction and the cytosolic calcium level in fura-2-loaded A7r5 cells. Molecular docking study also revealed the potential of ESC to bind L-type calcium (Ca_v1) channels. Our results demonstrate that ESC inhibits detrusor contractility via blocking Ca_v1 channels, which provides evidence for the direct effect of ESC on detrusor contractility and its mechanism.

Does sex influence near-infrared spectroscopy-derived indicators of microvascular reactivity and the response to acute dietary capsaicin

Endothelial dysfunction is associated with cardiovascular disease development, nitric oxide (NO) deficiencies, and may be limb or sex-specific. Prior in vitro work indicated that the transient receptor potential vanilloid channel-1 (TRPV₁) is expressed in human arteries and the TRPV₁ agonist capsaicin alters vasodilation in an endothelium-dependent manner; however, it is unknown if this translates in vivo or is limb or sex-dependent. Therefore, we sought to determine if there was limb or sex-specificity in the effect of capsaicin on microvascular function using near-infrared spectroscopy (NIRS)-derived tissue oxygen saturation (StO₂) reperfusion slope. In a blinded placebo-controlled crossover design, 45 young males (M: n = 25) and females (F: n = 20), the reperfusion slopes of the forearm and quadriceps were assessed, and a urine sample obtained to assay for nitrate/nitrite (NOx) concentrations and antioxidant capacity after acutely ingesting placebo or capsaicin. Under placebo, females had greater reperfusion rates in both the forearm (M: 0.44 ± 0.24 vs. F: 0.98 ± 0.46 %/sec; p = 0.002, d = -1.50) and quadricep (M: 0.86 ± 0.31 vs. F: 1.17 ± 0.43 %/sec; p = 0.010, d = -0.85). Capsaicin decreased microvascular responsiveness in the forearm of females (placebo: 0.98 ± 0.45 vs. capsaicin: 0.84 ± 0.45 %/sec) as compared to males (placebo: 0.45 ± 0.24 vs. capsaicin: 0.38 ± 0.16 %/sec, interaction p < 0.001, η² = 0.475). There was a sex*treatment interaction for NOx concentrations, where males increased (placebo: 21.13 ± 12.83 vs. capsaicin: 23.82 ± 13.34 μM), while females decreased (placebo: 22.78 ± 14.40 vs. capsaicin: 14.43 ± 10.01 μM; p = 0.037, η² = 0.042). Using NIRS to assess microvascular function, there is apparent limb and sex-specificity, and, for the first-time, document that acute oral capsaicin alters reperfusion slope in a sexually divergent manner.

Multiphasic changes in smooth muscle Ca2+ transporters during the progression of coronary atherosclerosis

Ischemic heart disease due to macrovascular atherosclerosis and microvascular dysfunction is the major cause of death worldwide and the unabated increase in metabolic syndrome is a major reason why this will continue. Intracellular free Ca²⁺ ([Ca²⁺]_i) regulates a variety of cellular functions including contraction, proliferation, migration, and transcription. It follows that studies of vascular Ca²⁺ regulation in reductionist models and translational animal models are vital to understanding vascular health and disease. Swine with metabolic syndrome (MetS) develop the full range of coronary atherosclerosis from mild to severe disease. Intravascular imaging enables quantitative measurement of atherosclerosis in vivo, so viable coronary smooth muscle (CSM) cells can be dispersed from the arteries to enable Ca²⁺ transport studies in native cells. Transition of CSM from the contractile phenotype in the healthy swine to the proliferative phenotype in mild atherosclerosis was associated with increases in SERCA activity, sarcoplasmic reticulum Ca²⁺, and voltage-gated Ca²⁺ channel function. In vitro organ culture confirmed that SERCA activation induces CSM proliferation. Transition from the proliferative to a more osteogenic phenotype was associated with decreases in all three Ca²⁺ transporters. Overall, there was a biphasic change in Ca²⁺ transporters over the progression of atherosclerosis in the swine model and this was confirmed in CSM from failing explanted hearts of humans. A major determinant of endolysosome content in human CSM is the severity of atherosclerosis. In swine CSM endolysosome Ca²⁺ release occurred through the TPC2 channel. We propose a multiphasic change in Ca²⁺ transporters over the progression of coronary atherosclerosis.

Vascular CaV1.2 channels in diabetes

Diabetic vasculopathy is a significant cause of morbidity and mortality in the diabetic population. Hyperglycemia, one of the central metabolic abnormalities in diabetes, has been associated with vascular dysfunction due to endothelial cell damage. However, studies also point toward vascular smooth muscle as a locus for hyperglycemia-induced vascular dysfunction. Emerging evidence implicates hyperglycemia-induced regulation of vascular L-type Ca²⁺ channels Ca_V1.2 as a potential mechanism for vascular dysfunction during diabetes. This chapter summarizes our current understanding of vascular Ca_V1.2 channels and their regulation during physiological and hyperglycemia/diabetes conditions. We will emphasize the role of Ca_V1.2 in vascular smooth muscle, the effects of elevated glucose on Ca_V1.2 function, and the mechanisms underlying its dysregulation in hyperglycemia and diabetes. We conclude by examining future directions and gaps in knowledge regarding Ca_V1.2 regulation in health and during diabetes.

Endothelial Cells and the Cerebral Circulation

Endothelial cells form the innermost layer of all blood vessels and are the only vascular component that remains throughout all vascular segments. The cerebral vasculature has several unique properties not found in the peripheral circulation; this requires that the cerebral endothelium be considered as a unique entity. Cerebral endothelial cells perform several functions vital for brain health. The cerebral vasculature is responsible for protecting the brain from external threats carried in the blood. The endothelial cells are central to this requirement as they form the basis of the blood-brain barrier. The endothelium also regulates fibrinolysis, thrombosis, platelet activation, vascular permeability, metabolism, catabolism, inflammation, and white cell trafficking. Endothelial cells regulate the changes in vascular structure caused by angiogenesis and artery remodeling. Further, the endothelium contributes to vascular tone, allowing proper perfusion of the brain which has high energy demands and no energy stores. In this article, we discuss the basic anatomy and physiology of the cerebral endothelium. Where appropriate, we discuss the detrimental effects of high blood pressure on the cerebral endothelium and the contribution of cerebrovascular disease endothelial dysfunction and dementia. © 2022 American Physiological Society. Compr Physiol 12:3449-3508, 2022.

RuBPY decreases intracellular calcium by decreasing influx and increasing storage

RuBPY is a ruthenium complex NO donor that presents a nitrite in its moiety and has been shown to induce vasodilation in various arteries, as well as arterial pressure reduction with no changes in heart rate. Since vascular tone is highly dependent on the cytosolic calcium concentration ([Ca²⁺ ]c), the current study aimed to investigate the effects of RuBPY on the intracellular mobilization of calcium stores of rat aortic vascular smooth muscle cells. Vascular reactivity experiments were performed in isolated aortic rings that were contracted with a high concentration of KCl or phenylephrine (Phe). Moreover, primary cultured vascular smooth muscle cells were used to measure [Ca²⁺ ]c by confocal microscopy. The NO donor RuBPY decreased the [Ca²⁺ ]c and reduced KCl and Phe -induced contractile responses. The selective inhibitor of sarco-endoplasmic Ca-ATPase (SERCA) with thapsigargin impaired the effect of RuBPY on Phe -induced contractile response. RuBPY also reduced caffeine-induced contraction, and the contraction dependent on the capacitive Ca²⁺ influx. Therefore, our results suggest that NO released from RuBPY decreased [Ca²⁺ ]c by calcium influx blockade, and activation of guanylyl-cyclase-cGMP-GK pathway. These results indicate that RuBPY increases Ca²⁺ storage in the sarcoplasmic reticulum by SERCA activation, and also by capacitive Ca²⁺ influx inhibition, which is dependent on the intracellular release of nitric oxide from this compound. This article is protected by copyright. All rights reserved.

Ability of 2-Chloro-N-(1-(3,4-dimethoxyphenyl)propan-2-yl)-2-phenylacetamide to Stimulate Endogenous Nitric Oxide Synthesis

Papaverine is one of the isoquinoline alkaloids derived from opium which is a vasodilator and smooth muscle relaxant. Using its chemical structure as a basic model, we synthesized 2-chloro-N-(1-(3,4-dimethoxyphenyl)propan-2-yl)-2-phenylacetamide as an isoquinoline precursor (IQP). Aim: Clarifying the nature of the relationship between IQP as a new biologically active molecule and the neurotransmitters acetylcholine (ACh) and serotonin (5-hydroxytryptamine, 5-HT), as well as with the nitric oxide (NO). Materials and methods: The IQP compound was tested on the isolated gastric smooth muscle preparations (SMPs) from rats to determine its effects on spontaneous contractile activity. NO concentration in tissue homogenates was determined, and immunohistochemistry was used to visualize the expression of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) in smooth muscle (SM) cells. Results: The data from the isometric measurements suggest that IQP has an additional specific action affecting the intracellular signaling pathways of 5-HT. Using immunohistochemistry, we found that the combination of 5-HT and IQP affected the density and intensity of nNOS-positive cells, which increase significantly in the myenteric plexus and SM cells. Conclusions: In conclusion, IQP is involved in the regulation of intestinal neurons expressing nNOS, affects the function of nNOS/NO, and, by this mechanism, probably regulates the spontaneous contractile activity of gastric SM.

A Systemic Review of the Integral Role of TRPM2 in Ischemic Stroke: From Upstream Risk Factors to Ultimate Neuronal Death

Ischemic stroke causes a heavy health burden worldwide, with over 10 million new cases every year. Despite the high prevalence and mortality rate of ischemic stroke, the underlying molecular mechanisms for the common etiological factors of ischemic stroke and ischemic stroke itself remain unclear, which results in insufficient preventive strategies and ineffective treatments for this devastating disease. In this review, we demonstrate that transient receptor potential cation channel, subfamily M, member 2 (TRPM2), a non-selective ion channel activated by oxidative stress, is actively involved in all the important steps in the etiology and pathology of ischemic stroke. TRPM2 could be a promising target in screening more effective prophylactic strategies and therapeutic medications for ischemic stroke.

Mechanisms and Physiological Implications of Cooperative Gating of Ion Channels Clusters

Ion channels play a central role in the regulation of nearly every cellular process. Dating back to the classic 1952 Hodgkin-Huxley model of the generation of the action potential, ion channels have always been thought of as independent agents. A myriad of recent experimental findings exploiting advances in electrophysiology, structural biology, and imaging techniques, however, have posed a serious challenge to this long-held axiom as several classes of ion channels appear to open and close in a coordinated, cooperative manner. Ion channel cooperativity ranges from variable-sized oligomeric cooperative gating in voltage-gated, dihydropyridine-sensitive Ca_v1.2 and Ca_v1.3 channels to obligatory dimeric assembly and gating of voltage-gated Na_v1.5 channels. Potassium channels, transient receptor potential channels, hyperpolarization cyclic nucleotide-activated channels, ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP₃Rs) have also been shown to gate cooperatively. The implications of cooperative gating of these ion channels range from fine tuning excitation-contraction coupling in muscle cells to regulating cardiac function and vascular tone, to modulation of action potential and conduction velocity in neurons and cardiac cells, and to control of pace-making activity in the heart. In this review, we discuss the mechanisms leading to cooperative gating of ion channels, their physiological consequences and how alterations in cooperative gating of ion channels may induce a range of clinically significant pathologies.

Opposing Responses of the Calcium Channel Blocker Nicardipine to Vascular Stiffness in the Elastic and Muscular Arteries in Rabbits

AIM

The cardio-ankle vascular index (CAVI) consists of intrinsic and functional arterial stiffness mainly regulated by vasoactive compounds. A new stiffness index of the aorta (aBeta) and iliac-femoral arteries (ifBeta) was determined by applying the CAVI theory to the whole aorta and iliac-femoral arteries. We investigated the changes in aBeta and ifBeta in response to decreased blood pressure (BP) induced by the Ca2＋ channel blocker nicardipine to elucidate the involvement of Ca2＋ in aBeta and ifBeta.

METHODS

Pressure waves at the origin of the aorta (oA), distal end of the abdominal aorta (dA), and left femoral artery (fA) as well as flow waves at the oA were simultaneously recorded before and after the infusion of nicardipine (50 µg/kg/min) for 2 min in 12 male rabbits under pentobarbital anesthesia. Beta was calculated using the following formula: Beta=2ρ / PP×ln (SBP / DBP)×PWV2, where ρ, SBP, DBP, and PP denote blood density and systolic, diastolic, and pulse pressures, respectively. aBeta, ifBeta, and aortic-iliac-femoral Beta (aifBeta) were calculated using aPWV, ifPWV, and aifPWV, respectively.

RESULTS

SBP, mean arterial pressure (MAP), DBP, and total peripheral vascular resistance significantly decreased during the administration of nicardipine, whereas cardiac output significantly increased. aBeta and ifBeta significantly increased and decreased, respectively, whereas aifBeta did not change despite the decrease in BP. ifBeta and aBeta positively and negatively correlated with BP, respectively, whereas aifBeta did not correlate with SBP.

CONCLUSIONS

There were contradictory arterial responses to nicardipine between the elastic and muscular arteries. Unknown vasoconstriction mechanisms that are not involved in Ca2＋ influx may function in the aorta in response to decreased BP.

Relevance of stromal interaction molecule 1 (STIM1) in experimental and human stroke

Stroke represents a main cause of death and permanent disability worldwide. In the attempt to develop targeted preventive and therapeutic strategies, several efforts were performed over the last decades to identify the specific molecular abnormalities preceding cerebral ischemia and neuronal death. In this regard, mitochondrial dysfunction, autophagy, and intracellular calcium homeostasis appear important contributors to stroke development, as underscored by recent pre-clinical evidence. Intracellular calcium (Ca²⁺) homeostasis is regulated, among other mechanisms, by the calcium sensor stromal interaction molecule 1 (STIM1) and calcium release-activated calcium modulator (ORAI) members, which mediate the store-operated Ca²⁺ entry (SOCE). The activity of SOCE is deregulated in animal models of ischemic stroke, leading to ischemic injury exacerbation. We found a different pattern of expression of few SOCE components, dependent from a STIM1 mutation, in cerebral endothelial cells isolated from the stroke-prone spontaneously hypertensive rat (SHRSP), compared to the stroke-resistant (SHRSR) strain, suggesting a potential involvement of this mechanism into the stroke predisposition of SHRSP. In this article, we discuss the relevant role of STIM1 in experimental stroke, as highlighted by the current literature and by our recent experimental findings, and the available evidence in the human disease. We also provide a glance on future perspectives and clinical implications of STIM1.

Hypothalamic miR-204 Induces Alteration of Heart Electrophysiology and Neurogenic Hypertension by Regulating the Sympathetic Nerve Activity: Potential Role of Microbiota

There is abundant evidence demonstrating the association between gut dysbiosis and neurogenic diseases such as hypertension. A common characteristic of resistant hypertension is the chronic elevation in sympathetic nervous system (SNS) activity accompanied by increased release of norepinephrine (NE), indicating a neurogenic component that contributes to the development of hypertension. Factors that modulate the sympathetic tone to the cardiovascular system in hypertensive patients are still poorly understood. Research has identified an interaction between the brain and the gut, and this interaction plays a possible role in the mechanism of heart damage-induced hypertension. Data, however, remain scarce, and further study is required to define the role of microbiota in sympathetic neural function and its relationship with heart damage and blood pressure (BP) control. Experimental evidence has pointed toward a bidirectional relationship between alterations in the types of bacteria present in the gut and neurogenic diseases, such as hypertension. Our published data showed that miR-204, a microRNA that plays an important role in the CNS function, is affected by gut dysbiosis. Therefore, miR-204 could be a key element that regulates normal sinus rhythm and neuronal hypertension. In this review, we will shed light on the potential mechanism by which microbiota affects hypothalamic miR-204, which in turn, could hinder the sympathetic nerve drive to the cardiovascular system leading to arrhythmia and hypertension.

The anti-diabetic drug trelagliptin induces vasodilation via activation of Kv channels and SERCA pumps

AIMS

In this study, we investigated the vasodilatory effects of trelagliptin (a dipeptidyl peptidase-4 inhibitor) and its related mechanisms using rabbit aortic rings.

MAIN METHODS

Arterial tone measurement was performed in rabbit thoracic aortic rings.

KEY FINDINGS

Trelagliptin induced vasodilation in a dose-dependent manner. Pretreatment with the ATP-sensitive K⁺ channel inhibitor glibenclamide, large-conductance Ca²⁺-activated K⁺ channel inhibitor paxilline, and inwardly rectifying K⁺ channel inhibitor Ba²⁺ did not affect the vasodilatory effect of trelagliptin. However, pretreatment with the voltage-dependent K⁺ (Kv) channel inhibitors 4-aminopyridine and tetraethylammonium significantly attenuated the vasodilatory effect of trelagliptin, suggesting that the vasodilatory effect of trelagliptin is associated with Kv channel activation. Although pretreatment with Kv1.5 and Kv2.1 subtype inhibitors did not affect the response to trelagliptin, pretreatment with a Kv7.X subtype inhibitor effectively reduced the vasodilatory effect of trelagliptin. Furthermore, sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitors also significantly attenuated the vasodilatory effect of trelagliptin. These effects, however, were not affected by pretreatment with Ca²⁺ channel inhibitors, adenylyl cyclase/PKA inhibitors, guanylyl cyclase/PKG inhibitors, or removal of the endothelium.

SIGNIFICANCE

From these results, we concluded that the vasodilatory effect of trelagliptin was associated with the activation of Kv channels (primary the Kv7.X subtype) and SERCA pump regardless of other K⁺ channels, Ca²⁺ channels, cAMP/PKA-related or cGMP/PKG-related signaling pathways, and the endothelium. Therefore, caution is required when prescribing trelagliptin to the patients with hypotension and diabetes.

Aldosterone Secretion in Patients With Primary Hyperparathyroidism Without Arterial Hypertension

OBJECTIVE

There is a direct bidirectional link between parathyroid hormone (PTH) and the renin-angiotensin-aldosterone system (RAAS), but few studies evaluated the RAAS in patients with primary hyperparathyroidism (PHPT), mainly biased from concomitant antihypertensive treatment.

METHODS

We retrospectively evaluated a consecutive series of 130 normotensive patients with PHPT comparing aldosterone (ALD) levels and plasma renin activity (PRA) with the demographic, biochemical, or clinical features of PHPT.

RESULTS

No correlation was found between ALD and PRA, and the demographic, biochemical, and bone densitometry parameters in patients with PHPT without hypertension, with the exception of a negative correlation between age and serum PRA. Moreover, there was no significant correlation between PTH and ALD levels even in patients whose PTH level was >100 ng/L (P = .088).

CONCLUSION

In our normotensive patients with PHPT, the ALD, PRA, and aldosterone/renin ratio were not correlated to PTH and calcium levels. In addition, they were neither related to PHPT clinical presentation nor renal function, vitamin D status, bone mass loss, or the presence of comorbidities such as diabetes and obesity. Further studies are needed to clarify the complex interplay between PTH and the RAAS in the modern PHPT presentation.

The inhibitory effect of trimetazidine on detrusor contractility - a potential repositioning of trimetazidine for the treatment of overactive bladder

OBJECTIVES

This study aimed to identify the effect of trimetazidine (TMZ), an antianginal drug, on detrusor smooth muscle (DSM) contractility and its possible mechanisms of action.

METHODS

We performed in-vitro contractility studies on isolated mouse DSM strips and investigated the effect of TMZ on Ca2+ levels in fura-2-loaded A7r5 cells.

KEY FINDINGS

TMZ (300 or 1000 µM) inhibited carbachol (CCh)- and KCl-induced contractions and produced a concentration-dependent (10-1000 µM) relaxation in KCl-precontracted DSM strips. TMZ-induced relaxation was markedly decreased by BaCl2, an inward-rectifying K+ channel blocker, but was not altered by preincubation with tetraethylammonium, glibenclamide, 4-aminopyridine, propranolol, L-NAME or methylene blue. TMZ (300 or 1000 µM) reduced both the CaCl2-induced contraction of depolarized DSM strips under Ca2+-free conditions and the CCh-induced contraction of DSM strips preincubated with nifedipine in Ca2+-containing Krebs solution. Furthermore, TMZ (1000 µM) significantly decreased the Ca2+ levels in fura-2-loaded A7r5 cells.

CONCLUSIONS

TMZ decreased DSM contractility and caused a concentration-dependent relaxation of the tissue possibly through its actions on Ca2+ transients and K+ channels. Our results provide preclinical evidence that TMZ would be a potential candidate to treat disorders related to the overactivity of the bladder.

Cellular and molecular effects of hyperglycemia on ion channels in vascular smooth muscle

Diabetes affects millions of people worldwide. This devastating disease dramatically increases the risk of developing cardiovascular disorders. A hallmark metabolic abnormality in diabetes is hyperglycemia, which contributes to the pathogenesis of cardiovascular complications. These cardiovascular complications are, at least in part, related to hyperglycemia-induced molecular and cellular changes in the cells making up blood vessels. Whereas the mechanisms mediating endothelial dysfunction during hyperglycemia have been extensively examined, much less is known about how hyperglycemia impacts vascular smooth muscle function. Vascular smooth muscle function is exquisitely regulated by many ion channels, including several members of the potassium (K+) channel superfamily and voltage-gated L-type Ca2+ channels. Modulation of vascular smooth muscle ion channels function by hyperglycemia is emerging as a key contributor to vascular dysfunction in diabetes. In this review, we summarize the current understanding of how diabetic hyperglycemia modulates the activity of these ion channels in vascular smooth muscle. We examine underlying mechanisms, general properties, and physiological relevance in the context of myogenic tone and vascular reactivity.

Vascular Kv7 channels control intracellular Ca2+ dynamics in smooth muscle

Voltage-gated Kv7 (or KCNQ) channels control activity of excitable cells, including vascular smooth muscle cells (VSMCs), by setting their resting membrane potential and controlling other excitability parameters. Excitation-contraction coupling in muscle cells is mediated by Ca2+ but until now, the exact role of Kv7 channels in cytosolic Ca2+ dynamics in VSMCs has not been fully elucidated. We utilised microfluorimetry to investigate the impact of Kv7 channel activity on intracellular Ca2+ levels and electrical activity of rat A7r5 VSMCs and primary human internal mammary artery (IMA) SMCs. Both, direct (XE991) and G protein coupled receptor mediated (vasopressin, AVP) Kv7 channel inhibition induced robust Ca2+ oscillations, which were significantly reduced in the presence of Kv7 channel activator, retigabine, L-type Ca2+ channel inhibitor, nifedipine, or T-type Ca2+ channel inhibitor, NNC 55-0396, in A7r5 cells. Membrane potential measured using FluoVolt exhibited a slow depolarisation followed by a burst of sharp spikes in response to XE991; spikes were temporally correlated with Ca2+ oscillations. Phospholipase C inhibitor (edelfosine) reduced AVP-induced, but not XE991-induced Ca2+ oscillations. AVP and XE991 induced a large increase of [Ca2+]i in human IMA, which was also attenuated with retigabine, nifedipine and NNC 55-0396. RT-PCR, immunohistochemistry and electrophysiology suggested that Kv7.5 was the predominant Kv7 subunit in both rat and human arterial SMCs; CACNA1C (Cav1.2; L-type) and CACNA1 G (Cav3.1; T-type) were the most abundant voltage-gated Ca2+ channel gene transcripts in both types of VSMCs. This study establishes Kv7 channels as key regulators of Ca2+ signalling in VSMCs with Kv7.5 playing a dominant role.

An additional physiological role for HSP70: Assistance of vascular reactivity

AIMS

HSP70, a molecular chaperone, helps to maintain proteostasis. In muscle biology, however, evidence suggests HSP70 to have a more versatile range of functions, as genetic deletion of its inducible genes impairs Ca²⁺ handling, and consequently, cardiac and skeletal muscle contractility. Still, it is unknown whether HSP70 is involved in vascular reactivity, an intrinsic physiological mechanism of blood vessels. Therefore, we designed this study to test the hypothesis that proper vascular reactivity requires the assistance of HSP70.

MAIN METHODS

We performed functional studies in a wire-myograph using thoracic aorta isolated from male Sprague Dawley rats. Experiments were conducted with and without an HSP70 inhibitor as well as in heat-stressed vessels. The expression levels of HSP70 were evaluated with Western blotting. NO and ROS levels were assessed with fluorescence microscopy.

KEY FINDINGS

We report that blockade of HSP70 weakens contraction in response to phenylephrine (dose-response) in the aorta. Additionally, we demonstrated that inhibition of HSP70 affects the amplitude of the fast and of the slow components of the time-force curve. Corroborating these findings, we found that inhibition of HSP70, in vessels over-expressing this protein, partly rescues the contractile phenotype of aortic rings. Furthermore, we show that blockade of HSP70 facilitates relaxation in response to acetylcholine and clonidine without affecting the basal levels of NO and ROS.

SIGNIFICANCE

Our work introduces an additional physiological role for HSP70, the assistance of vascular reactivity, which highlights this protein as a new player in vascular physiology, and therefore, uncovers a promising research avenue for vascular diseases.

Aging alters spontaneous and neurotransmitter-mediated Ca2+ signaling in smooth muscle cells of mouse mesenteric arteries

OBJECTIVE

Aging impairs MA dilation by reducing the ability of sensory nerves to counteract sympathetic vasoconstriction. This study tested whether altered SMC Ca²⁺ signals to sympathetic (NE) and sensory (CGRP) neurotransmitters underlie aging-related deficits in vasodilation.

METHODS

MAs from young and old mice were pressurized and loaded with Fluo-4 dye for confocal measurement of SMC Ca²⁺ sparks and waves. Endothelial denudation resolved the influence of ECs. SMCs were immunolabeled for RyR isoforms and compared with transcript levels for RyRs and CGRP receptor components.

RESULTS

SMCs from young vs old mice exhibited more spontaneous Ca²⁺ spark sites with no difference in Ca²⁺ waves. NE reduced spark sites and increased waves for both groups; addition of CGRP restored sparks and reduced waves only for young mice. Endothelial denudation attenuated Ca²⁺ responses to CGRP for young but not old mice, which were already attenuated, suggesting a diminished role for ECs with aging. CGRP receptor expression was similar between ages with increased serum CGRP in old mice, where RyR1 expression was replaced by RyR3.

CONCLUSION

With aging, we suggest that altered RyR expression in SMCs contributes to impaired ability of sensory neurotransmission to restore Ca²⁺ signaling underlying vasomotor control during sympathetic activation.

Disambiguating the role of blood flow and global signal with partial information decomposition

Global signal (GS) is an ubiquitous construct in resting state functional magnetic resonance imaging (rs-fMRI), associated to nuisance, but containing by definition most of the neuronal signal. Global signal regression (GSR) effectively removes the impact of physiological noise and other artifacts, but at the same time it alters correlational patterns in unpredicted ways. Performing GSR taking into account the underlying physiology (mainly the blood arrival time) has been proven to be beneficial. From these observations we aimed to: 1) characterize the effect of GSR on network-level functional connectivity in a large dataset; 2) assess the complementary role of global signal and vessels; and 3) use the framework of partial information decomposition to further look into the joint dynamics of the global signal and vessels, and their respective influence on the dynamics of cortical areas. We observe that GSR affects intrinsic connectivity networks in the connectome in a non-uniform way. Furthermore, by estimating the predictive information of blood flow and the global signal using partial information decomposition, we observe that both signals are present in different amounts across intrinsic connectivity networks. Simulations showed that differences in blood arrival time can largely explain this phenomenon, while using hemodynamic and calcium mouse recordings we were able to confirm the presence of vascular effects, as calcium recordings lack hemodynamic information. With these results we confirm network-specific effects of GSR and the importance of taking blood flow into account for improving de-noising methods. Additionally, and beyond the mere issue of data denoising, we quantify the diverse and complementary effect of global and vessel BOLD signals on the dynamics of cortical areas.

Integration of Rap1 and Calcium Signaling

Ca²⁺ is a universal intracellular signal. The modulation of cytoplasmic Ca²⁺ concentration regulates a plethora of cellular processes, such as: synaptic plasticity, neuronal survival, chemotaxis of immune cells, platelet aggregation, vasodilation, and cardiac excitation–contraction coupling. Rap1 GTPases are ubiquitously expressed binary switches that alternate between active and inactive states and are regulated by diverse families of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Active Rap1 couples extracellular stimulation with intracellular signaling through secondary messengers—cyclic adenosine monophosphate (cAMP), Ca²⁺, and diacylglycerol (DAG). Much evidence indicates that Rap1 signaling intersects with Ca²⁺ signaling pathways to control the important cellular functions of platelet activation or neuronal plasticity. Rap1 acts as an effector of Ca²⁺ signaling when activated by mechanisms involving Ca²⁺ and DAG-activated (CalDAG-) GEFs. Conversely, activated by other GEFs, such as cAMP-dependent GEF Epac, Rap1 controls cytoplasmic Ca²⁺ levels. It does so by regulating the activity of Ca²⁺ signaling proteins such as sarcoendoplasmic reticulum Ca²⁺-ATPase (SERCA). In this review, we focus on the physiological significance of the links between Rap1 and Ca²⁺ signaling and emphasize the molecular interactions that may offer new targets for the therapy of Alzheimer’s disease, hypertension, and atherosclerosis, among other diseases.

Ex Situ Liver Machine Perfusion: The Impact of Fresh Frozen Plasma

The primary aim of this single-center, phase 1 exploratory study was to investigate the safety, feasibility, and impact on intrahepatic hemodynamics of a fresh frozen plasma (FFP)-based perfusate in ex situ liver normothermic machine perfusion (NMP) preservation. Using an institutionally developed perfusion device, 21 livers (13 donations after brain death and 8 donations after circulatory death) were perfused for 3 hours 21 minutes to 7 hours 52 minutes and successfully transplanted. Outcomes were compared in a 1:4 ratio to historical control patients matched according to donor and recipient characteristics and preservation time. Perfused livers presented a very low resistance state with high flow during ex situ perfusion (arterial and portal flows 340 ± 150 and 890 ± 70 mL/minute/kg liver, respectively). This hemodynamic state was maintained even after reperfusion as demonstrated by higher arterial flow observed in the NMP group compared with control patients (220 ± 120 versus 160 ± 80 mL/minute/kg liver, P = 0.03). The early allograft dysfunction (EAD) rate, peak alanine aminotransferase (ALT), and peak aspartate aminotransferase (AST) levels within 7 days after transplantation were lower in the NMP group compared with the control patients (EAD 19% versus 46%, P = 0.02; peak ALT 363 ± 318 versus 1021 ± 999 U/L, P = 0.001; peak AST 1357 ± 1492 versus 2615 ± 2541 U/L, P = 0.001 of the NMP and control groups, respectively). No patient developed ischemic type biliary stricture. One patient died, and all other patients are alive and well at a follow-up of 12-35 months. No device-related adverse events were recorded. In conclusion, with this study, we showed that ex situ NMP of human livers can be performed safely and effectively using a noncommercial device and an FFP-based preservation solution. Future studies should further investigate the impact of an FFP-based perfusion solution on liver hemodynamics during ex situ normothermic machine preservation.

Role of the potassium channels in vasorelaxant effect of asafoetida essential oil

OBJECTIVE

In a previous work, we showed that asafoetida essential oil (AEO), from oleo-gum resin of Ferula asafoetida L. from the Apiaceae family, has a vasodilatory effect. This effect was both endothelium-dependent and endothelium-independent. The present study was designed to determine whether potassium channels and intracellular calcium release contribute to AEO-induced vasodilation.

MATERIALS AND METHODS

Rats' thoracic aorta were isolated and denuded. Following induction of contraction by potassium chloride (60 mM), concentration-response curve was plotted by the cumulative addition of AEO (0.625-80 µl/l to the medium of rings. The vasodilatory effect of AEO was assessed before and after addition of phenylephrine and potassium channel blockers (including barium chloride (BC), 4-aminopyridine (4A) and glibenclamide (Gl)).

RESULTS

AEO relaxed the precontracted rings in a concentration-dependent manner (IC50=23 µl/l). All potassium channel blockers significantly attenuated the vasodilatory activity of AEO when they were added to rings medium before addition of KCl (p<0.01, 4A and Gl groups and p< 0.001, BC group vs. control group) but not after that. In contrast to K channel blockers, adding AEO before or after phenylephrine, the tension was reduced significantly (p<0.05 vs. the control group).

CONCLUSION

The findings of this study indicated that the vasodilatory effect of AEO on denuded-endothelium aortic ring was mediated through activation of potassium channels and reduced intracellular calcium release.

Regulation of Blood Pressure by Targeting CaV1.2-Galectin-1 Protein Interaction

BACKGROUND

L-type Ca_V1.2 channels play crucial roles in the regulation of blood pressure. Galectin-1 (Gal-1) has been reported to bind to the I-II loop of Ca_V1.2 channels to reduce their current density. However, the mechanistic understanding for the downregulation of Ca_V1.2 channels by Gal-1 and whether Gal-1 plays a direct role in blood pressure regulation remain unclear.

METHODS

In vitro experiments involving coimmunoprecipitation, Western blot, patch-clamp recordings, immunohistochemistry, and pressure myography were used to evaluate the molecular mechanisms by which Gal-1 downregulates Ca_V1.2 channel in transfected, human embryonic kidney 293 cells, smooth muscle cells, arteries from Lgasl1^-/- mice, rat, and human patients. In vivo experiments involving the delivery of Tat-e9c peptide and AAV5-Gal-1 into rats were performed to investigate the effect of targeting Ca_V1.2-Gal-1 interaction on blood pressure monitored by tail-cuff or telemetry methods.

RESULTS

Our study reveals that Gal-1 is a key regulator for proteasomal degradation of Ca_V1.2 channels. Gal-1 competed allosterically with the Ca_Vβ subunit for binding to the I-II loop of the Ca_V1.2 channel. This competitive disruption of Ca_Vβ binding led to Ca_V1.2 degradation by exposing the channels to polyubiquitination. It is notable that we demonstrated that the inverse relationship of reduced Gal-1 and increased Ca_V1.2 protein levels in arteries was associated with hypertension in hypertensive rats and patients, and Gal-1 deficiency induces higher blood pressure in mice because of the upregulated Ca_V1.2 protein level in arteries. To directly regulate blood pressure by targeting the Ca_V1.2-Gal-1 interaction, we administered Tat-e9c, a peptide that competed for binding of Gal-1 by a miniosmotic pump, and this specific disruption of Ca_V1.2-Gal-1 coupling increased smooth muscle Ca_V1.2 currents, induced larger arterial contraction, and caused hypertension in rats. In contrasting experiments, overexpression of Gal-1 in smooth muscle by a single bolus of AAV5-Gal-1 significantly reduced blood pressure in spontaneously hypertensive rats.

CONCLUSIONS

We have defined molecularly that Gal-1 promotes Ca_V1.2 degradation by replacing Ca_Vβ and thereby exposing specific lysines for polyubiquitination and by masking I-II loop endoplasmic reticulum export signals. This mechanistic understanding provided the basis for targeting Ca_V1.2-Gal-1 interaction to demonstrate clearly the modulatory role that Gal-1 plays in regulating blood pressure, and offering a potential approach for therapeutic management of hypertension.

Sodium-activated potassium channels moderate excitability in vascular smooth muscle

KEY POINTS

We report that a sodium-activated potassium current, IKNa , has been inadvertently overlooked in both conduit and resistance arterial smooth muscle cells. IKNa is a major K+ resting conductance and is absent in cells of IKNa knockout (KO) mice. The phenotype of the IKNa KO is mild hypertension, although KO mice react more strongly than wild-type with raised blood pressure when challenged with vasoconstrictive agents. IKNa is negatively regulated by angiotensin II acting through Gαq protein-coupled receptors. In current clamp, KO arterial smooth muscle cells have easily evoked Ca2+ -dependent action potentials.

ABSTRACT

Although several potassium currents have been reported to play a role in arterial smooth muscle (ASM), we find that one of the largest contributors to membrane conductance in both conduit and resistance ASMs has been inadvertently overlooked. In the present study, we show that IKNa , a sodium-activated potassium current, contributes a major portion of macroscopic outward current in a critical physiological voltage range that determines intrinsic cell excitability; IKNa is the largest contributor to ASM cell resting conductance. A genetic knockout (KO) mouse strain lacking KNa channels (KCNT1 and KCNT2) shows only a modest hypertensive phenotype. However, acute administration of vasoconstrictive agents such as angiotensin II (Ang II) and phenylephrine results in an abnormally large increase in blood pressure in the KO animals. In wild-type animals Ang II acting through Gαq protein-coupled receptors down-regulates IKNa , which increases the excitability of the ASMs. The complete genetic removal of IKNa in KO mice makes the mutant animal more vulnerable to vasoconstrictive agents, thus producing a paroxysmal-hypertensive phenotype. This may result from the lowering of cell resting K+ conductance allowing the cells to depolarize more readily to a variety of excitable stimuli. Thus, the sodium-activated potassium current may serve to moderate blood pressure in instances of heightened stress. IKNa may represent a new therapeutic target for hypertension and stroke.

Bioinorganics and Wound Healing

Wound dressings and the healing enhancement (increasing healing speed and quality) are two components of wound care that lead to a proper healing. Wound care today consists mostly of providing an optimal environment by removing waste and necrotic tissues from a wound, preventing infections, and keeping the wounds adequately moist. This is however often not enough to re-establish the healing process in chronic wounds; with the local disruption of vascularization, the local environment is lacking oxygen, nutrients, and has a modified ionic and molecular concentration which limits the healing process. This disruption may affect cellular ionic pumps, energy production, chemotaxis, etc., and will affect the healing process. Biomaterials for wound healing range from simple absorbents to sophisticated bioactive delivery vehicles. Often placing a material in or on a wound can change multiple parameters such as pH, ionic concentration, and osmolarity, and it can be challenging to pinpoint key mechanism of action. This article reviews the literature of several inorganic ions and molecules and their potential effects on the different wound healing phases and their use in new wound dressings.

Prosopis alba seed flour improves vascular function in a rabbit model of high fat diet-induced metabolic syndrome

AIMS

Prosopis alba flour is a natural source of nutrient and phytochemicals with potential effects on cardiovascular risk factors. The aim of this work was to examine the effects of dietary supplementation with Prosopis alba seed flour (Pr-Feed) on a high fat diet (FD)-induced rabbit model of metabolic syndrome.

MAIN METHODS

Rabbits were separated in four groups: fed regular diet (CD); CD supplemented with Pr-Feed; fed on 18 % FD; FD supplemented with Pr-Feed. All diets were administrated for 6 weeks. After the feeding period body weights, mean blood pressure, heart rate and visceral abdominal fat (VAF) were determined; glucose tolerance test (GTT) was performed; total cholesterol (TC), HDL-cholesterol, LDL-cholesterol, triglycerides (TG), fasting glucose (FG), aspartate amino transferase, alanine amino transferase, bilirubin and creatinine were measured in serum. Abdominal aorta was excised and vascular function was assessed by acetylcholine relaxation and contractile response to KCl, norepinephrine and angiotensin II.

KEY FINDINGS

Phytochemical analyses showed that the main compounds of Pr-Feed were apigenin C-glycosides. FD increased VAF, FG, TG, reduced HDL-cholesterol and induced abnormal GTT. Pr-Feed addition to FD did not modify these alterations. Aortic rings from rabbits fed on FD exhibited an impaired relaxation-response to acetylcholine and increased agonist vasoconstrictor responses. Pr Feed-supplemented FD improved the response to acetylcholine, and prevented the increase of the contractile response to KCl, norepinephrine and angiotensin II.

SIGNIFICANCE

Results suggest that dietary supplementation with Pr-Feed, rich in apigenin C-glycosides, has vascular protector properties and could be used to prevent vascular alterations characterizing the metabolic syndrome.