Nitric oxide and cGMP cause vasorelaxation by activation of a charybdotoxin-sensitive K channel by cGMP-dependent protein kinase

Comprehensive analysis of perioperative hypotension in photodynamic diagnosis-assisted transurethral resection of bladder tumor with 5-aminolevulinic acid

OBJECTIVE

Intraoperative hypotension remains a serious adverse event of photodynamic diagnosis-assisted transurethral resection of bladder tumor with oral administration of 5-aminolevulinic acid. We conducted a re-analysis of perioperative hypotension in photodynamic diagnosis-assisted transurethral resection of the bladder tumor with oral 5-aminolevulinic acid to ascertain its safety.

METHODS

A total of 407 cases who underwent transurethral resection of bladder tumors in our institution were reviewed (274 cases for the PDD group with photodynamic diagnosis and 133 for the white light (WL) group without). A classification of hypotension severity was devised to identify risk factors for clinically troublesome hypotension. The distribution of hypotension severity in each of the PDD and WL groups was compared. Additionally, the patient background and perioperative data by hypotension severity were compared only in the PDD group.

RESULTS

More patients with moderate and severe hypotension were noted in the PDD group. The renal function was lower with increasing hypotension severity in the PDD group. More patients on general anesthesia were included in the mild and moderate hypotension group, whereas more patients on spinal anesthesia were included in the severe hypotension group. Furthermore, the frequency of side effects other than hypotension tended to increase with hypotension severity.

CONCLUSIONS

Renal function impairment and the other adverse effects of 5-aminolevulinic acid may be risk factors for severe hypotension. Mild or moderate hypotension may be caused by general anesthesia and severe hypotension may be caused by spinal anesthesia. To elucidate specific risk factors, further case-control studies are warranted.

Ion Channels Remodeling in the Regulation of Vascular Hyporesponsiveness During Shock

Shock is characterized with vascular hyporesponsiveness to vasoconstrictors, thereby to cause refractory hypotension, insufficient tissue perfusion, and multiple organ dysfunction. The vascular hyporeactivity persisted even though norepinephrine and fluid resuscitation were administrated, it is of critical importance to find new potential target. Ion channels are crucial in the regulation of cell membrane potential and affect vasoconstriction and vasodilation. It has been demonstrated that many types of ion channels including K+ channels, Ca2+ permeable channels, and Na+ channels exist in vascular smooth muscle cells and endothelial cells, contributing to the regulation of vascular homeostasis and vasomotor function. An increasing number of studies suggested that the structural and functional alterations of ion channels located in arteries contribute to vascular hyporesponsiveness during shock, but the underlying mechanisms remained to be fully clarified. Therefore, the expression and functional changes in ion channels in arteries associated with shock are reviewed, to pave the way for further exploring the potential of ion channel-targeted compounds in treating refractory hypotension in shock.

Microglia-neuron-vascular interactions in ischemia

Cerebral ischemia is a devastating condition that results in impaired blood flow in the brain leading to acute brain injury. As the most common form of stroke, occlusion of cerebral arteries leads to a characteristic sequence of pathophysiological changes in the brain tissue. The mechanisms involved, and comorbidities that determine outcome after an ischemic event appear to be highly heterogeneous. On their own, the processes leading to neuronal injury in the absence of sufficient blood supply to meet the metabolic demand of the cells are complex and manifest at different temporal and spatial scales. While the contribution of non-neuronal cells to stroke pathophysiology is increasingly recognized, recent data show that microglia, the main immune cells of the central nervous system parenchyma, play previously unrecognized roles in basic physiological processes beyond their inflammatory functions, which markedly change during ischemic conditions. In this review, we aim to discuss some of the known microglia-neuron-vascular interactions assumed to contribute to the acute and delayed pathologies after cerebral ischemia. Because the mechanisms of neuronal injury have been extensively discussed in several excellent previous reviews, here we focus on some recently explored pathways that may directly or indirectly shape neuronal injury through microglia-related actions. These discoveries suggest that modulating gliovascular processes in different forms of stroke and other neurological disorders might have presently unexplored therapeutic potential in combination with neuroprotective and flow restoration strategies.

Electrochemical Detection of Gasotransmitters: Status and Roadmap

Gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), are a class of gaseous, endogenous signaling molecules that interact with one another in the regulation of critical cardiovascular, immune, and neurological processes. The development of analytical sensing mechanisms for gasotransmitters, especially multianalyte mechanisms, holds vast importance and constitutes a growing area of study. This review provides an overview of electrochemical sensing mechanisms with an emphasis on opportunities in multianalyte sensing. Electrochemical methods demonstrate good sensitivity, adequate selectivity, and the most well-developed potential for the multianalyte detection of gasotransmitters. Future research will likely address challenges with sensor stability and biocompatibility (i.e., sensor lifetime and cytotoxicity), sensor miniaturization, and multianalyte detection in biological settings.

Vasodilation and Blood Pressure-Lowering Effect of 3-Demethyl-2-Geranyl-4-Prenylbellidifoline, a Xanthone Obtained from Garcinia achachairu, in Hypertensive Rats

3-demethyl-2-geranyl-4-prenylbellidifoline (DGP), a natural xanthone isolated from Garcinia achachairu, has previously demonstrated remarkable diuretic and renal protective actions. The present study expands its actions on the cardiovascular system by evaluating its vasorelaxant and blood pressure-lowering effects in spontaneously hypertensive rats (SHRs). Aortic endothelium-intact (E+) preparations of SHRs pre-contracted by phenylephrine and exposed to cumulative concentrations of G. achachairu extract, fractions, and DGP exhibited a significant relaxation compared to vehicle-only exposed rings. The non-selective muscarinic receptor antagonist (atropine), the non-selective inhibitor of nitric oxide synthase (L-NAME), as well as the inhibitor of soluble guanylate cyclase (ODQ) altogether avoided DGP-induced relaxation. Tetraethylammonium (small conductance Ca2+-activated K+ channel blocker), 4-aminopyridine (a voltage-dependent K+ channel blocker), and barium chloride (an influx-rectifying K+ channel blocker) significantly reduced DGP capacity to induce relaxation without the interference of glibenclamide (an ATP-sensitive inward rectifier 6.1 and 6.2 K+ channel blocker). Additionally, administration of DGP, 1 mg/kg i.v., decreased the mean, systolic, and diastolic arterial pressures, and the heart rate of SHRs. The natural xanthone DGP showed promising potential as an endothelium-dependent vasorelaxant, operating through the nitric oxide pathway and potassium channels, ultimately significantly reducing blood pressure in hypertensive rats.

Role of K+ and Ca2+ Channels in the Vasodilator Effects of Plectranthus barbatus (Brazilian Boldo) in Hypertensive Rats

Plectranthus barbatus, popularly known as Brazilian boldo, is used in Brazilian folk medicine to treat cardiovascular disorders including hypertension. This study investigated the chemical profile by UFLC-DAD-MS and the relaxant effect by using an isolated organ bath of the hydroethanolic extract of P. barbatus (HEPB) leaves on the aorta of spontaneously hypertensive rats (SHR). A total of nineteen compounds were annotated from HEPB, and the main metabolite classes found were flavonoids, diterpenoids, cinnamic acid derivatives, and organic acids. The HEPB promoted an endothelium-dependent vasodilator effect (~100%; EC50 ~347.10 μg/mL). Incubation of L-NAME (a nonselective nitric oxide synthase inhibitor; EC50 ~417.20 μg/mL), ODQ (a selective inhibitor of the soluble guanylate cyclase enzyme; EC50 ~426.00 μg/mL), propranolol (a nonselective α-adrenergic receptor antagonist; EC50 ~448.90 μg/mL), or indomethacin (a nonselective cyclooxygenase enzyme inhibitor; EC50 ~398.70 μg/mL) could not significantly affect the relaxation evoked by HEPB. However, in the presence of atropine (a nonselective muscarinic receptor antagonist), there was a slight reduction in its vasorelaxant effect (EC50 ~476.40 μg/mL). The addition of tetraethylammonium (a blocker of Ca2+-activated K+ channels; EC50 ~611.60 μg/mL) or 4-aminopyridine (a voltage-dependent K+ channel blocker; EC50 ~380.50 μg/mL) significantly reduced the relaxation effect of the extract without the interference of glibenclamide (an ATP-sensitive K+ channel blocker; EC50 ~344.60 μg/mL) or barium chloride (an influx rectifying K+ channel blocker; EC50 ~360.80 μg/mL). The extract inhibited the contractile response against phenylephrine, CaCl2, KCl, or caffeine, similar to the results obtained with nifedipine (voltage-dependent calcium channel blocker). Together, the HEPB showed a vasorelaxant effect on the thoracic aorta of SHR, exclusively dependent on the endothelium with the participation of muscarinic receptors and K+ and Ca2+ channels.

Protective effect of phosphorylated Athyrium multidentatum (Doll.) Ching polysaccharide on vascular endothelial cells in vitro and in vivo

The purpose of this study was to prepare phosphorylated Athyrium multidentatum (Doll.) Ching polysaccharide (PPS) and investigate its protective effect on vascular endothelial cells (VECs) in vitro and in vivo and the underlying mechanisms. Sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP) were used as phosphorylation reagents and PPS was characterized by Fourier transform infrared (FT-IR), 13 C nuclear magnetic resonance (13 C NMR) and 31 P nuclear magnetic resonance (31 P NMR) spectra. Chemical analysis demonstrated that PPS was composed of mannose, glucosamine, rhamnose, glucuronic acid, galacturonic acid, galactosamine, glucose, galactose, xylose, arabinose, and fucose with a molar ratio of 11.36:0.42:4.03:1.12:1.81:0.26:33.25:24.12:6.85:14.46:2.32 and a molecular weight of 28,837 Da. Results from in vitro and in vivo assays revealed that PPS protected human umbilical vein endothelial cells (HUVECs) against H2 O2 -induced oxidative injury and attenuated D-galactose-induced VECs damage in mice. RNA sequencing (RNA-seq) analysis identified 18 differentially expressed genes (DEGs) between D-galactose-treated and PPS-pretreated mice abdominal aorta. A deep analysis of these DEGs disclosed that PPS regulated the expression of genes involved in the functions of vascular endothelium repairment, cell growth and proliferation, cell survival and apoptosis, inflammation, angiogenesis and antioxidant, indicating that these biological processes might play crucial roles in the protective actions of PPS on VECs.

Restriction of C1-inhibitor activity in hereditary angioedema by dominant-negative effects of disease-associated SERPING1 gene variants

BACKGROUND

Patients with hereditary angioedema experience recurrent, sometimes life-threatening, attacks of edema. It is a rare genetic disorder characterized by genetic and clinical heterogenicity. Most cases are caused by genetic variants in the SERPING1 gene leading to plasma deficiency of the encoded protein C1 inhibitor (C1INH). More than 500 different hereditary angioedema-causing variants have been identified in the SERPING1 gene, but the disease mechanisms by which they result in pathologically low C1INH plasma levels remain largely unknown.

OBJECTIVES

The aim was to describe trans-inhibitory effects of full-length or near full-length C1INH encoded by 28 disease-associated SERPING1 variants.

METHODS

HeLa cells were transfected with expression constructs encoding the studied SERPING1 variants. Extensive and comparative studies of C1INH expression, secretion, functionality, and intracellular localization were carried out.

RESULTS

Our findings characterized functional properties of a subset of SERPING1 variants allowing the examined variants to be subdivided into 5 different clusters, each containing variants sharing specific molecular characteristics. For all variants except 2, we found that coexpression of mutant and normal C1INH negatively affected the overall capacity to target proteases. Strikingly, for a subset of variants, intracellular formation of C1INH foci was detectable only in heterozygous configurations enabling simultaneous expression of normal and mutant C1INH.

CONCLUSIONS

We provide a functional classification of SERPING1 gene variants suggesting that different SERPING1 variants drive the pathogenicity through different and in some cases overlapping molecular disease mechanisms. For a subset of gene variants, our data define some types of hereditary angioedema with C1INH deficiency as serpinopathies driven by dominant-negative disease mechanisms.

A synergistic blend of Garcinia mangostana fruit rind and Cinnamomum tamala leaf extracts enhances myogenic differentiation and mitochondrial biogenesis in vitro and muscle growth and strength in mice

Background

A proprietary combination of Garcinia mangostana fruit rind and Cinnamomum tamala leaf extracts (LI80020F4, CinDura®) improved the physical performance and muscle strength of resistance-trained adult males.

Objective

This study assessed the underlying mechanisms of the ergogenic potential of LI80020F4 in in vitro and in vivo models.

Methods

The individual extracts and their combination (LI80020F4) were assessed for nitrite production in EAhy926 human endothelial cells. Subsequent experiments evaluated the effect of LI80020F4 in myotube formation in C2C12 mouse myoblasts, expression of mammalian target of rapamycin (mTOR) signaling proteins, myogenic factors, and mitochondrial functions in L6 rat myoblasts.Moreover, adult male ICR mice were randomly assigned (n = 15) into vehicle control (G1), exercise alone (G2), oxymetholone-16 mg/kg body weight (bw) (G3), and 75 (G4)-, 150 (G5)-, or 300 (G6) mg/kg bw of LI80020F4, orally gavaged for 28 days. G1 and G2 mice received 0.5% carboxymethylcellulose sodium. Following completion, muscle strength and physical performance were assessed on forelimb grip strength and forced swimming test (FST), respectively. Gastrocnemius (GA), tibialis anterior (TA) muscle weights, muscle fiber cross-sectional area (CSA), levels of muscle, and serum protein markers were also determined.

Results

LI80020F4 increased nitrite production in EAhy926 cells in a dose-dependent manner. LI80020F4 induced C2C12 myotube formation, increased mitochondrial biogenesis, upregulated the expressions of activated mTOR and other mitochondria and myogenic proteins, and mitigated H2O2-induced mitochondrial membrane depolarization in the myoblast cells. In the animal study, 75, 150, and 300 mg/kg bw LI80020F4 doses significantly (P < 0.05) increased the animals' forelimb grip strength. Mid- and high-dose groups showed increased swimming time, increased muscle weight, CSA, muscle growth-related, and mitochondrial protein expressions in the GA muscles.

Conclusion

LI80020F4 increases nitric oxide production in the endothelial cells, mitochondrial biogenesis and function, upregulates skeletal muscle growth-related protein expressions and reduces oxidative stress; together, it explains the basis of the ergogenic potential of LI80020F4.

R-(+)-WIN55212-2 protects pericytes from ischemic damage and restores retinal microcirculatory patency after ischemia/reperfusion injury

BACKGROUND AND PURPOSE

Cannabinoids are vasoactive substances that act as key regulators of arterial tone in the blood vessels supplying peripheral tissues and the central nervous system. This study aimed to investigate the potential of R-(+)-WIN55212-2 (WIN), a cannabinoid receptor 1 agonist (CB1), as a treatment for retinal ischemia/reperfusion (I/R) injury.

EXPERIMENTAL APPROACH

Male Wistar rats were subjected to retinal I/R injury by increasing intraocular pressure in the anterior chamber. The rats were randomly divided into four groups: normal control, I/R, vehicle (pre-treated with dimethyl sulfoxide [DMSO] via intraperitoneal injection), and experimental (pre-treated with WIN at a dose of 1 ml/kg via intraperitoneal injection). The rats were sacrificed at different time points of reperfusion (1 hour, 3 hours, 6 hours, and 1 day) after inducing retinal I/R injury, and their retinas were collected for analysis. Oxygen-glucose deprived/reperfusion (OGD/R) was performed by initially perfusing the retinas with oxygenated artificial cerebrospinal fluid (ACSF), then switching to an OGD solution to simulate ischemia, followed by another perfusion with ACSF. Pericyte contraction and the "no-reflow" phenomenon were observed using infrared differential interference contrast (IR-DIC) microscopy and immunohistochemistry. Western blot, enzyme-linked immunosorbent assay (ELISA), and nitric oxide (NO) detection were used to explore the potential mechanism.

KEY RESULTS

In both the OGD/R and I/R models, retinal pericytes exhibited persistent contraction even after reperfusion. The ability of WIN to regulate the tone of retinal pericytes and capillaries was specifically blocked by the BKCa inhibitor iberiotoxin (100 nM). WIN demonstrated a protective effect against retinal I/R injury by preserving blood flow in vessels containing pericytes. Pretreatment with WIN alleviated the persistent contraction and apoptosis of retinal pericytes in I/R-induced rats, accompanied by a reduction in intracellular calcium ion (Ca2+) concentration. The expression of CB1 decreased in a time-dependent manner in the I/R group. After I/R injury, endothelium-derived nitric oxide (eNOS) levels were reduced at all time points, which was successfully reversed by WIN therapy except for the 1 day group. Additionally, the downregulation of cyclic guanosine monophosphate (cGMP) and BKCa expression at 3 hours, 6 hours, and 1 day after I/R injury was restored by pretreatment of WIN.

CONCLUSIONS & IMPLICATIONS

WIN exerted its protective effects on retinal I/R injury by inhibiting the contraction and apoptosis of pericytes through the CB1-eNOS-cGMP-BKCa signaling pathway, thus ameliorated the occlusion of retinal capillaries.

Pharmacotherapy of BPD: Current status & future perspectives

Bronchopulmonary dysplasia (BPD) is a disease exclusive to prematurity and has changed in its definition since Northway first described it in 1967. There have been countless clinical trials evaluating the efficacy of drugs in the treatment and prevention of BPD in human subjects, and an even larger number of animal studies. Despite these, only a handful of drugs are used at the bedside today, primarily due to the lack of consistent efficacy seen in clinical trials or due to reports of adverse effects. This review summarizes the list of the most commonly used drugs and emerging new therapies which target BPD and BPD-related pulmonary hypertension (BPD-PH), including those which have shown promise in human trials but are not yet used routinely.

The new quinazoline derivative (N2-methyl-N4-[(thiophen-2-yl)methyl]quinazoline-2,4-diamine) vasodilates isolated mesenteric arteries through endothelium-independent mechanisms and has acute hypotensive effects in Wistar rats

During the screening of new N2,N4-disubstituted quinazoline 2,4-diamines as phosphodiesterase-5 inhibitors and pulmonary artery vasodilators, one N2-methyl-N4-[(thiophen-2-yl)methyl]quinazoline-2,4-diamine (compound 8) presented a greater selectivity for systemic than pulmonary vasculature. The present study aimed to characterize its vasorelaxant and hypotensive effects in Wistar rats. Vasorelaxant effects of compound 8 and underlying mechanisms were evaluated on isolated mesenteric arteries. Acute hypotensive effect was evaluated in anesthetized rats. Additionally, cell viability and cytochrome P450 (CYP) activities were studied in rat isolated hepatocytes. Nifedipine was used as a comparator. Compound 8 induced a strong vasorelaxant effect, similar to nifedipine. This was unaffected by endothelium removal but was decreased by inhibitors of guanylate cyclase (ODQ) and KCa channel (iberiotoxin). Compound 8 enhanced sodium nitroprusside-induced relaxation, but inhibited vasoconstriction evoked by α1-adrenergic receptor activation and extracellular Ca2+ influx via receptor-operated Ca2+ channels. Acute intravenous infusion of compound 8 (0.05 and 0.1 mg/kg) produced hypotension. It showed similar potency to nifedipine for lowering diastolic and mean arterial blood pressure, but less so for the effect on systolic blood pressure. Compound 8 had no effect on hepatocyte viability and CYP activities except at high concentration (10 μM) at which a weak inhibitory effect on CYP1A and 3A was observed. In conclusion, this study identified a N2-methyl-N4-[(thiophen-2-yl)methyl]quinazoline-2,4-diamine with a potent vasodilator effect on resistance vessels, leading to an acute hypotensive effect and a low risk of liver toxicity or drug-drug interactions. These vascular effects were mediated mainly through sGC/cGMP pathway, opening of KCa channels, and inhibition of calcium entry.

Pathophysiology and probable etiology of cerebral small vessel disease in vascular dementia and Alzheimer's disease

Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.

Physiological and pathological characteristics of vascular endothelial injury in diabetes and the regulatory mechanism of autophagy

Vascular endothelial injury in diabetes mellitus (DM) is the major cause of vascular disease, which is closely related to the occurrence and development of a series of vascular complications and has a serious negative impact on a patient's health and quality of life. The primary function of normal vascular endothelium is to function as a barrier function. However, in the presence of DM, glucose and lipid metabolism disorders, insulin resistance, inflammatory reactions, oxidative stress, and other factors cause vascular endothelial injury, leading to vascular endothelial lesions from morphology to function. Recently, numerous studies have found that autophagy plays a vital role in regulating the progression of vascular endothelial injury. Therefore, this article compares the morphology and function of normal and diabetic vascular endothelium and focuses on the current regulatory mechanisms and the important role of autophagy in diabetic vascular endothelial injury caused by different signal pathways. We aim to provide some references for future research on the mechanism of vascular endothelial injury in DM, investigate autophagy's protective or injurious effect, and study potential drugs using autophagy as a target.

Peptide Lv Promotes Trafficking and Membrane Insertion of KCa3.1 through the MEK1-ERK and PI3K-Akt Signaling Pathways

Peptide Lv is a small endogenous secretory peptide that is proangiogenic through hyperpolarizing vascular endothelial cells (ECs) by enhancing the current densities of KCa3.1 channels. However, it is unclear how peptide Lv enhances these currents. One way to enhance the current densities of ion channels is to promote its trafficking and insertion into the plasma membrane. We hypothesized that peptide Lv-elicited KCa3.1 augmentation occurs through activating the mitogen-activated protein kinase kinase 1 (MEK1)-extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) signaling pathways, which are known to mediate ion channel trafficking and membrane insertion in neurons. To test this hypothesis, we employed patch-clamp electrophysiological recordings and cell-surface biotinylation assays on ECs treated with peptide Lv and pharmaceutical inhibitors of ERK and Akt. Blocking ERK or Akt activation diminished peptide Lv-elicited EC hyperpolarization and increase in KCa3.1 current densities. Blocking PI3K or Akt activation decreased the level of plasma membrane-bound, but not the total amount of KCa3.1 protein in ECs. Therefore, the peptide Lv-elicited EC hyperpolarization and KCa3.1 augmentation occurred in part through channel trafficking and insertion mediated by MEK1-ERK and PI3K-Akt activation. These results demonstrate the molecular mechanisms of how peptide Lv promotes EC-mediated angiogenesis.

L'utilisation du monoxyde d'azote inhalé chez les nouveau-nés

Le monoxyde d'azote inhalé (NOi), un vasodilatateur pulmonaire sélectif, est utilisé pour le traitement des nouveau-nés en insuffisance respiratoire hypoxémique (IRH) associée à une hypertension pulmonaire persistante du nouveau-né. Idéalement, il doit commencer à être administré après la confirmation échocardiographique de ce type d'hypertension. L'utilisation de NOi est recommandée chez les nouveau-nés peu prématurés ou à terme chez qui survient une IRH malgré des stratégies d'oxygénation ou de ventilation optimales. Cependant, il n'est pas recommandé d'y recourir systématiquement chez les nouveau-nés prématurés sous assistance respiratoire. On peut l'envisager comme traitement de secours chez les nouveau-nés prématurés en IRH précoce associée à une rupture prolongée des membranes ou à un oligoamnios, ou en IRH tardive en cas d'hypertension pulmonaire liée à une dysplasie bronchopulmonaire et accompagnée d'une insuffisance ventriculaire droite marquée. On peut aussi l'envisager chez les nouveau-nés atteints d'une hernie diaphragmatique congénitale qui présentent une IRH persistante, malgré un recrutement pulmonaire optimal, des signes échocardiographiques d'hypertension pulmonaire suprasystémique et un fonctionnement ventriculaire gauche approprié.

Inhaled nitric oxide use in newborns

Inhaled nitric oxide (iNO), a selective pulmonary vasodilator, is used as a therapeutic modality in infants with hypoxemic respiratory failure (HRF) associated with persistent pulmonary hypertension of the newborn (PPHN). iNO should ideally be initiated following echocardiographic confirmation of PPHN. Use of iNO is recommended in late preterm and term infants who develop HRF despite optimal oxygenation and ventilation strategies. However, routine iNO use in preterm infants on respiratory support is not recommended. iNO may be considered as a rescue modality in preterm infants with early-onset HRF when associated with prolonged rupture of membranes or oligohydramnios, or late-onset HRF in the context of bronchopulmonary dysplasia-associated pulmonary hypertension (PH) with severe right ventricular failure. A trial of iNO may also be considered for infants with congenital diaphragmatic hernia with persistent HRF despite optimal lung recruitment, and with echocardiographic evidence of supra-systemic PH and adequate left ventricular function.

Impact of COVID-19 on the cardiovascular health of women: a review by the Italian Society of Cardiology Working Group on 'gender cardiovascular diseases'

The coronavirus disease 19 (COVID-19), due to coronavirus 2 (SARS-CoV-2) infection, presents with an extremely heterogeneous spectrum of symptoms and signs. COVID-19 susceptibility and mortality show a significant sex imbalance, with men being more prone to infection and showing a higher rate of hospitalization and mortality than women. In particular, cardiovascular diseases (preexistent or arising upon infection) play a central role in COVID-19 outcomes, differently in men and women. This review will discuss the potential mechanisms accounting for sex/gender influence in vulnerability to COVID-19. Such variability can be ascribed to both sex-related biological factors and sex-related behavioural traits. Sex differences in cardiovascular disease and COVID-19 involve the endothelial dysfunction, the innate immune system and the renin-angiotensin system (RAS). Furthermore, the angiotensin-converting enzyme 2 (ACE2) is involved in disease pathogenesis in cardiovascular disease and COVID-19 and it shows hormone-dependent actions. The incidence of myocardial injury during COVID-19 is sex-dependent, predominantly in association with a greater degree of inflammation and coagulation disorders among men. Its pathogenesis is not fully elucidated, but the main theories foresee a direct role for the ACE2 receptor, the hyperimmune response and the RAS imbalance, which may also lead to isolated presentation of COVID-19-mediated myopericarditis. Moreover, the latest evidence on cardiovascular diseases and their relationship with COVID-19 during pregnancy will be discussed. Finally, authors will analyse the prevalence of the long-covid syndrome between the two sexes and its impact on the quality of life and cardiovascular health.

Vascularized Tissue Organoids

Tissue organoids hold enormous potential as tools for a variety of applications, including disease modeling and drug screening. To effectively mimic the native tissue environment, it is critical to integrate a microvasculature with the parenchyma and stroma. In addition to providing a means to physiologically perfuse the organoids, the microvasculature also contributes to the cellular dynamics of the tissue model via the cells of the perivascular niche, thereby further modulating tissue function. In this review, we discuss current and developing strategies for vascularizing organoids, consider tissue-specific vascularization approaches, discuss the importance of perfusion, and provide perspectives on the state of the field.

Endothelial IK and SK channel activation decreases pulmonary arterial pressure and vascular remodeling in pulmonary hypertension

Endothelial cells (ECs) from small pulmonary arteries (PAs) release nitric oxide (NO) and prostacyclin, which lower pulmonary arterial pressure (PAP). In pulmonary hypertension (PH), the levels of endothelium-derived NO and prostacyclin are reduced, contributing to elevated PAP. Small-and intermediate-conductance Ca²⁺-activated K⁺ channels (IK and SK)-additional crucial endothelial mediators of vasodilation-are also present in small PAs, but their function has not been investigated in PH. We hypothesized that endothelial IK and SK channels can be targeted to lower PAP in PH. Whole-cell patch-clamp experiments showed functional IK and SK channels in ECs, but not smooth muscle cells, from small PAs. Using a SU5416 plus chronic hypoxia (Su + CH) mouse model of PH, we found that currents through EC IK and SK channels were unchanged compared with those from normal mice. Moreover, IK/SK channel-mediated dilation of small PAs was preserved in Su + CH mice. Consistent with previous reports, endothelial NO levels and NO-mediated dilation were reduced in small PAs from Su + CH mice. Notably, acute treatment with IK/SK channel activators decreased PAP in Su + CH mice but not in normal mice. Further, chronic activation of IK/SK channels decreased PA remodeling and right ventricular hypertrophy, which are pathological hallmarks of PH, in Su + CH mice. Collectively, our data provide the first evidence that, unlike endothelial NO release, IK/SK channel activity is not altered in PH. Our results also demonstrate proof of principle that IK/SK channel activation can be used as a strategy for lowering PAP in PH.

Vascular Relaxation and Blood Pressure Lowering Effects of Prunus mume in Rats

Prunus mume Siebold et Zuccarini is mainly consumed as processed fruits in beverages, vinegar, alcohol, or fruit syrup; studies have reported various functional effects. Many pharmacological and functional studies exist on fruit extracts or processed foods using fruits, however, efficacy studies on various parts of P. mume, including the bark, branches, flowers, and leaves, have not been sufficiently conducted. A previous study revealed that a 70% ethanol extract of P. mume branches induced vascular endothelium-dependent vasorelaxant effects in rat thoracic aortic rings. Therefore, we hypothesized that various parts (the fruits, flowers, leaves, and bark) might have vasorelaxant effects. We evaluated the effects of P. mume extracts on the vascular relaxation of isolated rat thoracic aorta and hypotensive effects in spontaneous hypertensive rats (SHR). A 70% ethanol extract of P. mume bark (PBaE) was the most effective, thus, we investigated its vasorelaxant mechanisms and hypotensive effects. PBaE lowered the blood pressure in SHR and induced the vascular endothelium-dependent relaxation of isolated rat aortic rings via the NO/sGC/cGMP and the PGI₂ pathways in the vascular smooth muscle. Potassium channels, such as K_Ca, K_ATP, K_V, and K_ir, were partially associated with a PBaE-induced vasorelaxation. Therefore, PBaE might help prevent and treat hypertension.

Vasorelaxant Effect of Moroccan Cannabis sativa Threshing Residues on Rat Mesenteric Arterial Bed is Endothelium and Muscarinic Receptors Dependent

Introduction

Ethanolic fraction of Moroccan Cannabis sativa threshing residues (EFCS) was evaluated for its vasorelaxant activity. The current work aims to identify the active metabolites in the ethanolic fraction of the EFCS and illustrate their mechanism of action.

Methods

Free radical scavenging capacity of EFCS was assessed using DPPH method. The EFCS vasodilation activities in phenylephrine-precontracted isolated rat mesenteric arterial beds were investigated in presence of L-NAME (nitric oxide synthase inhibitor), indomethacin (cyclooxygenase inhibitor), potassium channel blockers (namely tetraetylamonium, barium chloride, and glibenclamide), and atropine. Nitric oxide vascular release was measured by electron paramagnetic resonance (EPR) using a spin trap in rat aortic rings.

Results

EFCS induced dose-dependent vasorelaxation on mesenteric vascular bed. Incubation of the preparations with L-NAME, ODQ (a soluble guanylyl cyclase inhibitor), or potassium channel blockers reduced the fall of perfusion pressure caused by EFCS. Endothelial denudation or atropine abolished the EFCS's vasorelaxant effect, suggesting involvement of muscarinic receptors and endothelium-relaxing factors. The extract induced nitric oxide release in aortic rings in a similar manner as acetylcholine suggesting an effect of EFCS on the muscarinic receptor and the conductance arteries. Chemical investigation of EFCS identified potential active components namely apigenin and derivatives of luteolin skeleton and also additional components such as neophytadiene, squalene, and β-sitosterol. In conclusion, the vasorelaxant effect of EFCS on rat mesenteric arterial bed, which is dependent of muscarinic receptor activation, nitric oxide, and EDHF, can account for potential therapeutic use against high blood pressure related cardiovascular diseases.

The good Samaritan glutathione-S-transferase P1: An evolving relationship in nitric oxide metabolism mediated by the direct interactions between multiple effector molecules

Glutathione-S-transferases (GSTs) are phase II detoxification isozymes that conjugate glutathione (GSH) to xenobiotics and also suppress redox stress. It was suggested that GSTs have evolved not to enhance their GSH affinity, but to better interact with and metabolize cytotoxic nitric oxide (NO). The interactions between NO and GSTs involve their ability to bind and store NO as dinitrosyl-dithiol iron complexes (DNICs) within cells. Additionally, the association of GSTP1 with inducible nitric oxide synthase (iNOS) results in its inhibition. The function of NO in vasodilation together with studies associating GSTM1 or GSTT1 null genotypes with preeclampsia, additionally suggests an intriguing connection between NO and GSTs. Furthermore, suppression of c-Jun N-terminal kinase (JNK) activity occurs upon increased levels of GSTP1 or NO that decreases transcription of JNK target genes such as c-Jun and c-Fos, which inhibit apoptosis. This latter effect is mediated by the direct association of GSTs with MAPK proteins. GSTP1 can also inhibit nuclear factor kappa B (NF-κB) signaling through its interactions with IKKβ and Iκα, resulting in decreased iNOS expression and the stimulation of apoptosis. It can be suggested that the inhibitory activity of GSTP1 within the JNK and NF-κB pathways may be involved in crosstalk between survival and apoptosis pathways and modulating NO-mediated ROS generation. These studies highlight an innovative role of GSTs in NO metabolism through their interaction with multiple effector proteins, with GSTP1 functioning as a "good Samaritan" within each pathway to promote favorable cellular conditions and NO levels.

Function and development of interneurons involved in brain tissue oxygen regulation

The regulation of oxygen in brain tissue is one of the most important fundamental questions in neuroscience and medicine. The brain is a metabolically demanding organ, and its health directly depends on maintaining oxygen concentrations within a relatively narrow range that is both sufficiently high to prevent hypoxia, and low enough to restrict the overproduction of oxygen species. Neurovascular interactions, which are responsible for oxygen delivery, consist of neuronal and glial components. GABAergic interneurons play a particularly important role in neurovascular interactions. The involvement of interneurons extends beyond the perspective of inhibition, which prevents excessive neuronal activity and oxygen consumption, and includes direct modulation of the microvasculature depending upon their sub-type. Namely, nitric oxide synthase-expressing (NOS), vasoactive intestinal peptide-expressing (VIP), and somatostatin-expressing (SST) interneurons have shown modulatory effects on microvessels. VIP interneurons are known to elicit vasodilation, SST interneurons typically cause vasoconstriction, and NOS interneurons have to propensity to induce both effects. Given the importance and heterogeneity of interneurons in regulating local brain tissue oxygen concentrations, we review their differing functions and developmental trajectories. Importantly, VIP and SST interneurons display key developmental milestones in adolescence, while NOS interneurons mature much earlier. The implications of these findings point to different periods of critical development of the interneuron-mediated oxygen regulatory systems. Such that interference with normal maturation processes early in development may effect NOS interneuron neurovascular interactions to a greater degree, while insults later in development may be more targeted toward VIP- and SST-mediated mechanisms of oxygen regulation.

The Functional Effects of Visfatin on Human Left Internal Mammary Artery

ABSTRACT

Visfatin may play a role in vascular dysfunction in metabolic disorders. Apart from its insulin-mimetic actions, it has divergent actions in the cardiovascular system with discordant results in the literature. Thus, we aimed to study the effects of visfatin on vascular responses of the human left internal mammary artery. Sections of redundant human left internal mammary artery were cut into 3-mm wide rings and hung in 20-mL organ baths containing physiologic salt solution and attached to an isometric force transducer connected to a computer-based data acquisition system. Removing endothelium caused an increase in pD2 values for visfatin-induced relaxation responses (10 -12 -10 -7 M) (9.06 ± 0.21 and 11.08 ± 0.92, respectively). Nicotinamide phosphoribosyltransferase inhibitor FK866 (10 µM) reversed the visfatin-induced relaxations (10 -12 -10 -7 M) ( P = 0.024). Incubations with nitric oxide synthase inhibitor nitro- l -arginine methylester and guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ) caused significant reductions in relaxation responses of visfatin ( P = 0.011 and 0.008, respectively). Visfatin incubations decreased relaxation responses to acetylcholine but not to sodium nitroprusside. Incubations with visfatin did not change contractile responses to angiotensin II, endothelin-1, noradrenalin, and phenylephrine. In this study, visfatin caused endothelium-dependent relaxations mediated by nitric oxide-cyclic guanosine monophosphate pathway and nicotinamide phosphoribosyltransferase activity. Furthermore, visfatin-induced decreases in relaxation responses were also related to endothelium-derived nitric oxide.

The role of angiotensin II and relaxin in vascular adaptation to pregnancy

In brief

There is a pregnancy-induced vasodilation of blood vessels, which is known to have a protective effect on cardiovascular function and can be maintained postpartum. This review outlines the cardiovascular changes that occur in a healthy human and rodent pregnancy, as well as different pathways that are activated by angiotensin II and relaxin that result in blood vessel dilation.

Abstract

During pregnancy, systemic and uteroplacental blood flow increase to ensure an adequate blood supply that carries oxygen and nutrients from the mother to the fetus. This results in changes to the function of the maternal cardiovascular system. There is also a pregnancy-induced vasodilation of blood vessels, which is known to have a protective effect on cardiovascular health/function. Additionally, there is evidence that the effects of maternal vascular vasodilation are maintained post-partum, which may reduce the risk of developing high blood pressure in the next pregnancy and reduce cardiovascular risk later in life. At both non-pregnant and pregnant stages, vascular endothelial cells produce a number of vasodilators and vasoconstrictors, which transduce signals to the contractile vascular smooth muscle cells to control the dilation and constriction of blood vessels. These vascular cells are also targets of other vasoactive factors, including angiotensin II (Ang II) and relaxin. The binding of Ang II to its receptors activates different pathways to regulate the blood vessel vasoconstriction/vasodilation, and relaxin can interact with some of these pathways to induce vasodilation. Based on the available literature, this review outlines the cardiovascular changes that occur in a healthy human pregnancy, supplemented by studies in rodents. A specific focus is placed on vasodilation of blood vessels during pregnancy; the role of endothelial cells and endothelium-derived vasodilators will also be discussed. Additionally, different pathways that are activated by Ang II and relaxin that result in blood vessel dilation will also be reviewed.

Glutathione-S-Transferases as Potential Targets for Modulation of Nitric Oxide-Mediated Vasodilation

Glutathione-S-transferases (GSTs) are highly promiscuous in terms of their interactions with multiple proteins, leading to various functions. In addition to their classical detoxification roles with multi-drug resistance-related protein-1 (MRP1), more recent studies have indicated the role of GSTs in cellular nitric oxide (NO) metabolism. Vasodilation is classically induced by NO through its interaction with soluble guanylate cyclase. The ability of GSTs to biotransform organic nitrates such as nitroglycerin for NO generation can markedly modulate vasodilation, with this effect being prevented by specific GST inhibitors. Recently, other structurally distinct pro-drugs that generate NO via GST-mediated catalysis have been developed as anti-cancer agents and also indicate the potential of GSTs as suitable targets for pharmaceutical development. Further studies investigating GST biochemistry could enhance our understanding of NO metabolism and lead to the generation of novel and innovative vasodilators for clinical use.

Safety and practicality of high dose inhaled nitric oxide in emergency department COVID-19 patients

BACKGROUND

Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator and mild bronchodilator that has been shown to improve systemic oxygenation, but has rarely been administered in the Emergency Department (ED). In addition to its favorable pulmonary vascular effects, in-vitro studies report that NO donors can inhibit replication of viruses, including SARS Coronavirus 2 (SARS-CoV-2). This study evaluated the administration of high-dose iNO by mask in spontaneously breathing emergency department (ED) patients with respiratory symptoms attributed to Coronavirus disease 2019 (COVID-19).

METHODS

We designed a randomized clinical trial to determine whether 30 min of high dose iNO (250 ppm) could be safely and practically administered by emergency physicians in the ED to spontaneously-breathing patients with respiratory symptoms attributed to COVID-19. Our secondary goal was to learn if iNO could prevent the progression of mild COVID-19 to a more severe state.

FINDINGS

We enrolled 47 ED patients with acute respiratory symptoms most likely due to COVID-19: 25 of 47 (53%) were randomized to the iNO treatment group; 22 of 47 (46%) to the control group (supportive care only). All patients tolerated the administration of high-dose iNO in the ED without significant complications or symptoms. Five patients receiving iNO (16%) experienced asymptomatic methemoglobinemia (MetHb) > 5%. Thirty-four of 47 (72%) subjects tested positive for SARS-CoV-2: 19 of 34 were randomized to the iNO treatment group and 15 of 34 subjects to the control group. Seven of 19 (38%) iNO patients returned to the ED, while 4 of 15 (27%) control patients did. One patient in each study arm was hospitalized: 5% in iNO treatment and 7% in controls. One patient was intubated in the iNO group. No patients in either group died. The differences between these groups were not significant.

CONCLUSION

A single dose of iNO at 250 ppm was practical and not associated with any significant adverse effects when administered in the ED by emergency physicians. Local disease control led to early study closure and prevented complete testing of COVID-19 safety and treatment outcomes measures.

Neonatal Anesthesia and Oxidative Stress

Neonatal anesthesia, while often essential for surgeries or imaging procedures, is accompanied by significant risks to redox balance in the brain due to the relatively weak antioxidant system in children. Oxidative stress is characterized by concentrations of reactive oxygen species (ROS) that are elevated beyond what can be accommodated by the antioxidant defense system. In neonatal anesthesia, this has been proposed to be a contributing factor to some of the negative consequences (e.g., learning deficits and behavioral abnormalities) that are associated with early anesthetic exposure. In order to assess the relationship between neonatal anesthesia and oxidative stress, we first review the mechanisms of action of common anesthetic agents, the key pathways that produce the majority of ROS, and the main antioxidants. We then explore the possible immediate, short-term, and long-term pathways of neonatal-anesthesia-induced oxidative stress. We review a large body of literature describing oxidative stress to be evident during and immediately following neonatal anesthesia. Moreover, our review suggests that the short-term pathway has a temporally limited effect on oxidative stress, while the long-term pathway can manifest years later due to the altered development of neurons and neurovascular interactions.

Pathophysiology of Atherosclerosis

Atherosclerosis is the main risk factor for cardiovascular disease (CVD), which is the leading cause of mortality worldwide. Atherosclerosis is initiated by endothelium activation and, followed by a cascade of events (accumulation of lipids, fibrous elements, and calcification), triggers the vessel narrowing and activation of inflammatory pathways. The resultant atheroma plaque, along with these processes, results in cardiovascular complications. This review focuses on the different stages of atherosclerosis development, ranging from endothelial dysfunction to plaque rupture. In addition, the post-transcriptional regulation and modulation of atheroma plaque by microRNAs and lncRNAs, the role of microbiota, and the importance of sex as a crucial risk factor in atherosclerosis are covered here in order to provide a global view of the disease.

Kv7 Channels in Cyclic-Nucleotide Dependent Relaxation of Rat Intra-Pulmonary Artery

Pulmonary hypertension is treated with drugs that stimulate cGMP or cAMP signalling. Both nucleotides can activate Kv7 channels, leading to smooth muscle hyperpolarisation, reduced Ca²⁺ influx and relaxation. Kv7 activation by cGMP contributes to the pulmonary vasodilator action of nitric oxide, but its contribution when dilation is evoked by the atrial natriuretic peptide (ANP) sensitive guanylate cyclase, or cAMP, is unknown. Small vessel myography was used to investigate the ability of Kv7 channel blockers to interfere with pulmonary artery relaxation when cyclic nucleotide pathways were stimulated in different ways. The pan-Kv7 blockers, linopirdine and XE991, caused substantial inhibition of relaxation evoked by NO donors and ANP, as well as endothelium-dependent dilators, the guanylate cyclase stimulator, riociguat, and the phosphodiesterase-5 inhibitor, sildenafil. Maximum relaxation was reduced without a change in sensitivity. The blockers had relatively little effect on cAMP-mediated relaxation evoked by forskolin, isoprenaline or treprostinil. The Kv7.1-selective blocker, HMR1556, had no effect on cGMP or cAMP-dependent relaxation. Western blot analysis demonstrated the presence of Kv7.1 and Kv7.4 proteins, while selective activators of Kv7.1 and Kv7.4 homomeric channels, but not Kv7.5, caused pulmonary artery relaxation. It is concluded that Kv7.4 channels contribute to endothelium-dependent dilation and the effects of drugs that act by stimulating cGMP, but not cAMP, signalling.

Reactive Oxygen Species Induced Pathways in Heart Failure Pathogenesis and Potential Therapeutic Strategies

With respect to structural and functional cardiac disorders, heart failure (HF) is divided into HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Oxidative stress contributes to the development of both HFrEF and HFpEF. Identification of a broad spectrum of reactive oxygen species (ROS)-induced pathways in preclinical models has provided new insights about the importance of ROS in HFrEF and HFpEF development. While current treatment strategies mostly concern neuroendocrine inhibition, recent data on ROS-induced metabolic pathways in cardiomyocytes may offer additional treatment strategies and targets for both of the HF forms. The purpose of this article is to summarize the results achieved in the fields of: (1) ROS importance in HFrEF and HFpEF pathophysiology, and (2) treatments for inhibiting ROS-induced pathways in HFrEF and HFpEF patients. ROS-producing pathways in cardiomyocytes, ROS-activated pathways in different HF forms, and treatment options to inhibit their action are also discussed.

Sodium Nitroprusside-Induced Activation of Vascular Smooth Muscle BK Channels Is Mediated by PKG Rather Than by a Direct Interaction with NO

Nitric oxide (NO) is a powerful vasodilator in different vascular beds and NO-donors are widely used in clinical practice. Early data suggested that NO and NO-donors activate vascular smooth muscle high-conductance, calcium-activated potassium channels (BK channels). There exist two hypotheses explaining the effect of NO and NO-donors on BK channels—one stating that protein kinase G (PKG) mediates the effect of NO, and the other one stating that NO acts directly on the channel. Thus, the degree of contribution of PKG to the NO-induced activation of the BK channel is still not completely clear. This study tested the hypothesis that the sodium nitroprusside (SNP)-induced activation of vascular smooth muscle BK channels is fully mediated by PKG. This hypothesis was investigated using the patch-clamp technique and freshly isolated smooth muscle cells from rat tail artery. In whole-cell experiments, SNP considerably increased the outward current compared with the addition of the bath solution. SNP did not alter the current in the presence of iberiotoxin, the specific blocker of BK channels, during co-application with hydroxocobalamin, an NO-scavenger, and in the presence of Rp-8-Br-PET-cGMPS, the specific PKG-inhibitor. In inside-out patches, the activity of BK channels was increased by SNP, SNAP, and DEA-NO. However, these effects did not differ from the effect of the application of drug-free bath solution. Furthermore, a similar increase in single BK channel activity was induced by Rp-8-Br-PET-cGMPS, Rp-8-Br-PET-cGMPS together with SNP, hydroxocobalamin, and hydroxocobalamin together with SNP or DEA-NO. Finally, the activity of excised BK channels did not change in the absence of any application but was considerably increased by PKG compared with the addition of drug-free bath solution. These results suggest that NO released from NO-donors stimulates the BK current only through activation of PKG.

Boldine, an Alkaloid from Peumus boldus Molina, Induces Endothelium-Dependent Vasodilation in the Perfused Rat Kidney: Involvement of Nitric Oxide and Small-Conductance Ca2+-Activated K+ Channel

Boldine, 2,9-dihydroxy-1,10-dimethoxyaporphine, is the main alkaloid found in the leaves and bark of Peumus boldus Molina. In recent years, boldine has demonstrated several pharmacological properties that benefit endothelial function, blood pressure control, and reduce damage in kidney diseases. However, the renal vasodilator effects and mechanisms remain unknown. Herein, perfused rat kidneys were used to study the ability of boldine to induce vasodilation of renal arteries. For that, left kidney preparations with and without functional endothelium were contracted with phenylephrine and received 10–300 nmol boldine injections. The preparations were then perfused for 15 min with phenylephrine plus L-NAME, indomethacin, KCl, tetraethylammonium, glibenclamide, apamin, charybdotoxin, or iberiotoxin. In 30, 100, and 300 nmol doses, boldine induced a dose-and endothelium-dependent relaxing effect on the renal vascular bed. No vasodilator effects were observed in preparations lacking functional endothelium. While the inhibition of the cyclooxygenase enzyme through the addition of indomethacin did not cause any change in the vasodilating action of boldine, the nonselective nitric oxide synthase inhibitor L-NAME fully precluded the vasodilatory action of boldine at all doses tested. The perfusion with KCl or tetraethylammonium (nonselective K⁺ channels blocker) also abolished the vasodilatory effect of boldine, indicating the participation of K⁺ channels in the renal action of boldine. The perfusion with glibenclamide (selective ATP-sensitive K⁺ channels blocker), iberiotoxin (selective high-conductance Ca²⁺-activated K⁺ channel blocker), and charybdotoxin (selective high- and intermediate-conductance Ca²⁺-activated K⁺ channel blocker) did not modify the vasodilatory action of boldine. On the other hand, the perfusion with apamin (selective small-conductance Ca²⁺-activated K⁺ channel blocker) completely prevented the vasodilatory action of boldine at all doses tested. Together, the present study showed the renal vasodilatory properties of boldine, an effect dependent on the generation of nitric oxide and the opening of a small-conductance Ca²⁺-activated K⁺ channel.

Endothelial Dysfunction after Hematopoietic Stem Cell Transplantation: A Review Based on Physiopathology

Endothelial dysfunction (ED) is frequently encountered in transplant medicine. ED is an argument of high complexity, and its understanding requires a wide spectrum of knowledge based on many fields of basic sciences such as molecular biology, immunology, and pathology. After hematopoietic stem cell transplantation (HSCT), ED participates in the pathogenesis of various complications such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), graft-versus-host disease (GVHD), transplant-associated thrombotic microangiopathy (TA-TMA), idiopathic pneumonia syndrome (IPS), capillary leak syndrome (CLS), and engraftment syndrome (ES). In the first part of the present manuscript, we briefly review some biological aspects of factors involved in ED: adhesion molecules, cytokines, Toll-like receptors, complement, angiopoietin-1, angiopoietin-2, thrombomodulin, high-mobility group B-1 protein, nitric oxide, glycocalyx, coagulation cascade. In the second part, we review the abnormalities of these factors found in the ED complications associated with HSCT. In the third part, a review of agents used in the treatment of ED after HSCT is presented.

Early Development of the GABAergic System and the Associated Risks of Neonatal Anesthesia

Human and animal studies have elucidated the apparent neurodevelopmental effects resulting from neonatal anesthesia. Observations of learning and behavioral deficits in children, who were exposed to anesthesia early in development, have instigated a flurry of studies that have predominantly utilized animal models to further interrogate the mechanisms of neonatal anesthesia-induced neurotoxicity. Specifically, while neonatal anesthesia has demonstrated its propensity to affect multiple cell types in the brain, it has shown to have a particularly detrimental effect on the gamma aminobutyric acid (GABA)ergic system, which contributes to the observed learning and behavioral deficits. The damage to GABAergic neurons, resulting from neonatal anesthesia, seems to involve structure-specific changes in excitatory-inhibitory balance and neurovascular coupling, which manifest following a significant interval after neonatal anesthesia exposure. Thus, to better understand how neonatal anesthesia affects the GABAergic system, we first review the early development of the GABAergic system in various structures that have been the focus of neonatal anesthesia research. This is followed by an explanation that, due to the prolonged developmental curve of the GABAergic system, the entirety of the negative effects of neonatal anesthesia on learning and behavior in children are not immediately evident, but instead take a substantial amount of time (years) to fully develop. In order to address these concerns going forward, we subsequently offer a variety of in vivo methods which can be used to record these delayed effects.

Association of 5-aminolevulinic acid with intraoperative hypotension in malignant glioma surgery

BACKGROUND

Use of 5-aminolevulinic acid for photodynamic malignant tumor diagnosis reportedly causes intraoperative hypotension (systolic blood pressure < 70 mmHg) during urologic surgery. However, its association with intraoperative hypotension in malignant glioma surgery and underlying mechanisms has not yet been elucidated.. This study aimed to investigate whether 5-aminolevulinic acid administration is associated with intraoperative hypotension in malignant glioma surgery and explore the mechanisms of 5-aminolevulinic acid-induced hypotension in vitro.

METHODS

In this retrospective multicenter cohort study, we investigated intracellular nitric oxide as a candidate mediator of hypotension in response to 5-aminolevulinic acid in vitro in human umbilical vein endothelial cell cultures.

RESULTS

Of 142 patients, 94 underwent 5-aminolevulinic acid-guided surgery. Systolic blood pressure was significantly lower throughout surgery with 5-aminolevulinic acid administration. 5-Aminolevulinic acid administration was an independent risk factor for intraoperative hypotension according to multivariable logistic regression analysis (89% vs. 56%; odds ratio = 6.72, 95% confidence interval [2.05-22.1], P = 002). In subgroup analysis of the 5-aminolevulinic acid group, increasing age and use of renin-angiotensin system inhibitors had a synergistic effect with 5-aminolevulinic acid on decreased blood pressure. In the vascular endothelial cell culture study, 5-aminolevulinic acid induced a significant increase in intracellular nitric oxide generation.

CONCLUSIONS

5-Aminolevulinic acid administration was associated with intraoperative hypotension in malignant glioma surgery, with increasing age and use of renin-angiotensin system inhibitors boosting the blood pressure-lowering effect of 5-aminolevulinic acid. According to in vitro results, the low blood pressure induced by 5-aminolevulinic acid may be mediated by a nitric oxide increase in vascular endothelial cells.

Ethyl Acetate Fraction from Leandra dasytricha (A. Gray) Cong. Leaves Promotes Vasodilatation and Reduces Blood Pressure in Normotensive and Hypertensive Rats

Leandra dasytricha (A. Gray) Cong. is widely distributed in the south of Brazil and is commonly used for cardiovascular and kidney ailments. For this study, we used male Wistar normotensive rats (NTRs) and spontaneously hypertensive rats (SHRs) to verify the effects of the ethyl acetate fraction (EAF) obtained from L. dasytricha leaves on isolated aorta relaxation and in the arterial blood pressure. The EAF was analyzed by LC-DAD-MS, and several components were annotated, including hydrolysable tannins, triterpenes, and O- and C-glycosylated dihydrochalcones, such as the most intense ion peak relative to C-hexosyl phloretin (nothofagin; compound number 13). The EAF caused a concentration and endothelium-dependent relaxation of the aorta in both NTRs and SHRs. This effect was abolished in the endothelium-denuded aorta. L-NAME, a nonselective nitric oxide synthase inhibitor, and ODQ, a soluble guanylate cyclase inhibitor, entirely blocked the EAF-induced relaxation. The presence of a muscarinic receptor antagonist or a cyclooxygenase inhibitor did not alter the EAF's effectiveness in relaxing the aorta. The preincubation with tetraethylammonium, a Ca²⁺-activated K⁺ channel blocker, and with 4-aminopyridine, a voltage-dependent K⁺ channel blocker, significantly interfered with the EAF's relaxation. However, the incubation with glibenclamide, an ATP-sensitive K⁺ channel blocker, and barium chloride, an inward-rectifier K⁺ channel blocker, did not interfere with the EAF-induced relaxation. The EAF treatment also caused a dose-dependent decrease in the mean arterial pressure, systolic arterial pressure, and diastolic arterial pressure of both NTRs and SHRs, without significantly interfering with heart rate values. In conclusion, this study demonstrated the EAF-induced vasorelaxant and hypotensive actions, primarily dependent on the endothelium function and mainly with the participation of the nitric oxide and Ca²⁺-activated and voltage-dependent K⁺ channels.

Differential hyperpolarization to substance P and calcitonin gene-related peptide in smooth muscle versus endothelium of mouse mesenteric artery

OBJECTIVE

We sought to define how sensory neurotransmitters substance P and calcitonin gene-related peptide (CGRP) affect membrane potential of vascular smooth muscle and endothelium.

METHODS

Microelectrodes recorded membrane potential of smooth muscle from pressurized mouse mesenteric arteries (diameter, ~150 µm) and in endothelial tubes.

RESULTS

Resting potential was similar (~ -45 mV) for each cell layer. Substance P hyperpolarized smooth muscle and endothelium ~ -15 mV; smooth muscle hyperpolarization was abolished by endothelial disruption or NO synthase inhibition. Blocking K_Ca channels (apamin + charybdotoxin) attenuated hyperpolarization in both cell types. CGRP hyperpolarized endothelium and smooth muscle ~ -30 mV; smooth muscle hyperpolarization was independent of endothelium. Blocking K_Ca channels prevented hyperpolarization to CGRP in endothelium but not smooth muscle. Inhibiting K_ATP channels with glibenclamide or genetic deletion of K_IR 6.1 attenuated hyperpolarization in smooth muscle but not endothelium. Pinacidil (K_ATP channel agonist) hyperpolarized smooth muscle more than endothelium (~ -35 vs. ~ -20 mV).

CONCLUSIONS

Calcitonin gene-related peptide elicits greater hyperpolarization than substance P. Substance P hyperpolarizes both cell layers through K_Ca channels and involves endothelium-derived NO in smooth muscle. Endothelial hyperpolarization to CGRP requires K_Ca channels, while K_ATP channels mediate hyperpolarization in smooth muscle. Differential K⁺ channel activation in smooth muscle and endothelium through sensory neurotransmission may selectively tune mesenteric blood flow.

Nitric Oxide Signals Through IRAG to Inhibit TRPM4 Channels and Dilate Cerebral Arteries

Nitric oxide (NO) relaxes vascular smooth muscle cells (SMCs) and dilates blood vessels by increasing intracellular levels of cyclic guanosine monophosphate (cGMP), which stimulates the activity of cGMP-dependent protein kinase (PKG). However, the vasodilator mechanisms downstream of PKG remain incompletely understood. Here, we found that transient receptor potential melastatin 4 (TRPM4) cation channels, which are activated by Ca²⁺ released from the sarcoplasmic reticulum (SR) through inositol triphosphate receptors (IP₃Rs) under native conditions, are essential for SMC membrane depolarization and vasoconstriction. We hypothesized that signaling via the NO/cGMP/PKG pathway causes vasodilation by inhibiting TRPM4. We found that TRPM4 currents activated by stretching the plasma membrane or directly activating IP₃Rs were suppressed by exogenous NO or a membrane-permeable cGMP analog, the latter of which also impaired IP₃R-mediated release of Ca²⁺ from the SR. The effects of NO on TRPM4 activity were blocked by inhibition of soluble guanylyl cyclase or PKG. Notably, upon phosphorylation by PKG, IRAG (IP₃R-associated PKG substrate) inhibited IP₃R-mediated Ca²⁺ release, and knockdown of IRAG expression diminished NO-mediated inhibition of TRPM4 activity and vasodilation. Using superresolution microscopy, we found that IRAG, PKG, and IP₃Rs form a nanoscale signaling complex on the SR of SMCs. We conclude that NO/cGMP/PKG signaling through IRAG inhibits IP₃R-dependent activation of TRPM4 channels in SMCs to dilate arteries.

SIGNIFICANCE STATEMENT

Nitric oxide is a gaseous vasodilator produced by endothelial cells that is essential for cardiovascular function. Although NO-mediated signaling pathways have been intensively studied, the mechanisms by which they relax SMCs to dilate blood vessels remain incompletely understood. In this study, we show that NO causes vasodilation by inhibiting the activity of Ca²⁺-dependent TRPM4 cation channels. Probing further, we found that NO does not act directly on TRPM4 but instead initiates a signaling cascade that inhibits its activation by blocking the release of Ca²⁺ from the SR. Thus, our findings reveal the essential molecular pathways of NO-induced vasodilation-a fundamental unresolved concept in cardiovascular physiology.

Large-conductance calcium-activated K+ channels, rather than KATP channels, mediate the inhibitory effects of nitric oxide on mouse lymphatic pumping

BACKGROUND AND PURPOSE

K_ATP channels are negative regulators of lymphatic vessel excitability and contractility and are proposed to be targets for immune cell products that inhibit lymph transport. Previous studies in rat and guinea pig mesenteric lymphatics found that NO-mediated inhibition of lymphatic contraction was prevented or reversed by the K_ATP channel inhibitor, glibenclamide. We revisited this hypothesis using mouse lymphatic vessels and K_ATP channel knockout mice.

EXPERIMENTAL APPROACH

Mouse popliteal lymphatics were isolated, and contractility was assessed using pressure myography. K⁺ channel expression was determined by PCR analysis of FACS-purified lymphatic smooth muscle cells.

KEY RESULTS

The NO-producing agonist, ACh, and the NO donor, NONOate, both produced dose-dependent inhibition of spontaneous lymphatic contractions that were blocked by the soluble GC inhibitor, ODQ, or the PKG inhibitor, Rp-8-Br-PET-cGMPS. Surprisingly, the inhibitory effects of both were preserved in K_ir 6.1^-/- vessels, suggesting that K_ATP channels did not mediate NO-induced responses. We hypothesized a role for BK channels, given their prominence in arterial smooth muscle. Indeed, BK channels were expressed in mouse lymphatic smooth muscle and NS11021 (a BK channel activator) caused dilation and reduced contraction frequency, whereas iberiotoxin and penitrem A (BK channel inhibitors) produced right-ward shifts in NONOate concentration-response curves.

CONCLUSION AND IMPLICATIONS

Inhibition of mouse lymphatic contractions by NO primarily involves activation of BK channels, rather than K_ATP channels. Thus, BK channels are a potential target for therapeutic reversal of lymph pump inhibition by NO generated by immune cell activation of iNOS in chronic lymphoedema.

Supplemental Watermelon Juice Attenuates Acute Hyperglycemia-Induced Macro-and Microvascular Dysfunction in Healthy Adults

BACKGROUND

Acute hyperglycemia reduces NO bioavailability and causes macro- and microvascular dysfunction. Watermelon juice (WMJ) is a natural source of the amino acid citrulline, which is metabolized to form arginine for the NO cycle and may improve vascular function.

OBJECTIVES

We examined the effects of 2 weeks of WMJ compared to a calorie-matched placebo (PLA) to attenuate acute hyperglycemia-induced vascular dysfunction.

METHODS

In a randomized, placebo-controlled, double-blind, crossover trial, 6 men and 11 women (aged 21-25; BMI, 23.5 ± 3.2 kg/m2) received 2 weeks of daily WMJ (500 mL) or a PLA drink followed by an oral-glucose-tolerance test. Postprandial flow-mediated dilation (FMD) was measured by ultrasound (primary outcome), while postprandial microvascular blood flow (MVBF) and ischemic reperfusion were measured by near-infrared spectroscopy (NIRS) vascular occlusion test (VOT).

RESULTS

The postprandial FMD area AUC was higher after WMJ supplementation compared to PLA supplementation (838 ± 459% · 90 min compared with 539 ± 278% · 90 min; P = 0.03). The postprandial MVBF (AUC) was higher (P = 0.01) following WMJ supplementation (51.0 ± 29.1 mL blood · 100 mL tissue-1 · min-1 · 90 min) compared to the PLA (36.0 ± 20.5 mL blood · 100 mL tissue-1 · min-1 · 90 min; P = 0.01). There was a significant treatment effect (P = 0.048) for WMJ supplementation (71.2 ± 1.5%) to increase baseline tissue oxygen saturation (StO2%) when compared to PLA (65.9 ± 1.7%). The ischemic-reperfusion slope was not affected by WMJ treatment (P = 0.83).

CONCLUSIONS

Two weeks of daily WMJ supplementation improved FMD and some aspects of microvascular function (NIRS-VOT) during experimentally induced acute hyperglycemia in healthy adults. Preserved postprandial endothelial function and enhanced skeletal muscle StO2% are likely partially mediated by increased NO production (via citrulline conversion into arginine) and by the potential antioxidant effect of other bioactive compounds in WMJ.

Characterization of endothelium-dependent and -independent processes in occipital artery of the rat: Relevance to control of blood flow to nodose sensory cells

Circulating factors access cell bodies of vagal afferents in nodose ganglia (NG) via the occipital artery (OA). Constrictor responses of OA segments closer in origin from the external carotid artery (ECA) differ from segments closer to NG. Our objective was to determine the role of endothelium in this differential vasoreactivity in rat OA segments. Vasoreactivity of OA segments (proximal segments closer to ECA, distal segments closer to NG) were examined in wire myographs. We evaluated (a) vasoconstrictor effects of 5-hydroxytryptamine (5-HT) in intact and endothelium-denuded OA segments in absence/presence of soluble guanylate cyclase (SGC) inhibitor ODQ, (b) vasodilator responses elicited by NO-donor MAHMA NONOate in intact or endothelium-denuded OA segments in absence/presence of ODQ, and (c) vasodilator responses elicited by endothelium-dependent vasodilator, acetylcholine (ACh), in intact OA segments in absence/presence of ODQ. Intact distal OA responded more to 5-HT than intact proximal OA. Endothelium denudation increased 5-HT potency in both OA segments, especially proximal OA. ODQ increased maximal responses of 5HT in both segments, particularly proximal OA. ACh similarly relaxed both OA segments, effects abolished by endothelial denudation and attenuated by ODQ. MAHMA NONOate elicited transient vasodilation in both segments. Effects of ODQ against ACh were segment-dependent whereas those against MAHMA NONOate were not. The endothelium regulates OA responsiveness in a segment-dependently fashion. Endothelial cells at the OA-ECA junction more strongly influence vascular tone than those closer to NG. Differential endothelial regulation of OA tone may play a role in controlling blood flow and access of circulating factors to NG.

A critical role of hepatic GABA in the metabolic dysfunction and hyperphagia of obesity

Hepatic lipid accumulation is a hallmark of type II diabetes (T2D) associated with hyperinsulinemia, insulin resistance, and hyperphagia. Hepatic synthesis of GABA, catalyzed by GABA-transaminase (GABA-T), is upregulated in obese mice. To assess the role of hepatic GABA production in obesity-induced metabolic and energy dysregulation, we treated mice with two pharmacologic GABA-T inhibitors and knocked down hepatic GABA-T expression using an antisense oligonucleotide. Hepatic GABA-T inhibition and knockdown decreased basal hyperinsulinemia and hyperglycemia and improved glucose intolerance. GABA-T knockdown improved insulin sensitivity assessed by hyperinsulinemic-euglycemic clamps in obese mice. Hepatic GABA-T knockdown also decreased food intake and induced weight loss without altering energy expenditure in obese mice. Data from people with obesity support the notion that hepatic GABA production and transport are associated with serum insulin, homeostatic model assessment for insulin resistance (HOMA-IR), T2D, and BMI. These results support a key role for hepatocyte GABA production in the dysfunctional glucoregulation and feeding behavior associated with obesity.

Vasorelaxant Effect of Novel Nitric Oxide-Hydrogen Sulfide Donor Chalcone in Isolated Rat Aorta: Involvement of cGMP Mediated sGC and Potassium Channel Activation

BACKGROUND AND OBJECTIVE

Recently, nitric oxide (NO) and hydrogen sulfide (H2S) donating moieties were extensively studied for their role in the vasculature as they are responsible for many cellular and pathophysiological functioning. The objective of the present study is to evaluate novel NO and H2S donating chalcone moieties on isolated rat aorta for vasorelaxation, and to investigate the probable mechanism of action.

METHODS

To extend our knowledge of vasorelaxation by NO and H2S donor drugs, here we investigated the vasorelaxing activity of novel NO and H2S donating chalcone moieties on isolated rat aorta. The mechanism of vasorelaxation by these molecules was investigated by performing in vitro cGMP mediated sGC activation assay and using Tetraethylammonium chloride (TEA) as a potassium channel blocker and Methylene blue as NO blocker.

RESULTS

Both NO and H2S donating chalcone moieties were found to be potent vasorelaxant. The compound G4 and G5 produce the highest vasorelaxation with 3.716 and 3.789 M of pEC50, respectively. After the addition of TEA, G4 and G5 showed 2.772 and 2.796 M of pEC50, respectively. The compounds Ca1, Ca2, and D7 produced significant activation and release of cGMP mediated sGC which was 1.677, 1.769 and 1.768 M of pEC50, respectively.

CONCLUSION

The vasorelaxation by NO-donating chalcones was blocked by Methylene blue but it did not show any effect on H2S donating chalcones. The vasorelaxing potency of NO-donating molecules was observed to be less affected by the addition of TEA but H2S donors showed a decrease in both efficacy and potency. The cGMP release was more in the case of NO-donating molecules. The tested compounds were found potent for relaxing vasculature of rat aorta.

Vericiguat for the treatment of heart failure: mechanism of action and pharmacological properties compared with other emerging therapeutic options

INTRODUCTION

The significant morbidity and mortality in patients with heart failure (HF), notably in the most advanced forms of the disease, justify the need for novel therapeutic options. In the last year, the soluble guanylate cyclase (sGC) stimulator, vericiguat, has drawn the attention of the medical community following the report of reduced clinical outcomes in patients with worsening chronic HF (WCHF).

AREAS COVERED

The authors review the available data on the mechanism of action of vericiguat (cyclic guanosine monophosphate (cGMP) pathway), its clinical development program, its role in HF management, and its future positioning in the therapeutic recommendations.

EXPERT OPINION

cGMP deficiency has deleterious effects on the heart and contributes to the progression of HF. Different molecules, including nitric oxide (NO) donors, phosphodiesterase inhibitors, and natriuretic peptides analogues, target the NO-sCG-cGMP pathway but have yielded conflicting results in HF patients. Vericiguat acts as a sGC stimulator thus targeting the NO-sGC-cGMP pathway by a different mechanism that complements the current pharmacotherapy for HF. Vericiguat has shown an additional statistical add-on therapy efficacy by reducing morbi-mortality in patients with WCHF. A better evaluation of HF severity might be an important determinant to guide the use of vericiguat among the available therapies.

Cigarette Smoke Directly Promotes Pulmonary Arterial Remodeling and Kv7.4 Channel Dysfunction

Rationale: Cigarette smoke is considered the chief leading cause of chronic obstructive pulmonary disease (COPD). Its impact on the progressive deterioration of airways has been extensively studied, but its direct effects on the pulmonary vasculature are less known. Objectives: To prove that pulmonary arterial remodeling in patients with COPD is not just a consequence of alveolar hypoxia but also due to the direct effects of cigarette smoke on the pulmonary vascular bed. Methods: We have used different molecular and cell biology approaches, as well as traction force microscopy, wire myography, and patch-clamp techniques in human cells and freshly isolated pulmonary arteries. In addition, we relied on in vivo models and human samples to analyze the effects of cigarette smoke on pulmonary vascular tone alterations. Measurements and Main Results: Cigarette smoke extract exposure directly promoted a hypertrophic, senescent phenotype that in turn contributed, through the secretion of inflammatory molecules, to an increase in the proliferative potential of nonexposed cells. Interestingly, these effects were significantly reversed by antioxidants. Furthermore, cigarette smoke extract affected cell contractility and dysregulated the expression and activity of the voltage-gated K+ channel Kv7.4. This contributed to the impairment of vasoconstriction and vasodilation responses. Most importantly, the levels of this channel were diminished in the lungs of smoke-exposed mice, smokers, and patients with COPD. Conclusions: Cigarette smoke directly contributes to pulmonary arterial remodeling through increased cell senescence, as well as vascular tone alterations because of diminished levels and function in the Kv7.4 channel. Strategies targeting these pathways may lead to novel therapies for COPD.