Cyclic nucleotide-dependent relaxation pathways in vascular smooth muscle

Insights into the identification of bitter peptides from Jinhua ham and its taste mechanism by molecular docking and transcriptomics analysis

In order to identify the peptides responsible for bitter defects and to understand the mechanism of bitterness in dry-cured ham, the peptides were identified by LC-MS/MS, and the interaction between bitter peptides and receptor proteins were evaluated by molecular docking and molecular dynamics simulation; the signal transduction mechanism of bitter peptides was investigated using the model of HEK-293T cells by calcium imaging and transcriptomics analysis. The results of LC-MS/MS showed that 11 peptides were identified from the high bitterness fraction of defective ham; peptides PKAPPAK, VTDTTR and YIIEK derived from titin showed the highest bitterness values compared with other peptides. The results of molecular docking showed that lower CDOCKER energy was observed in the interaction between these peptides and hT2R16 in comparison with these receptors of hT2R1, hT2R4, hT2R5, hT2R8 and hT2R14, and the interaction of hT2R16 and peptides was stabilized by hydrophobic interaction and hydrogen bond. The average RMSF values of VTDTTR were higher than that of YIIEK and PKAPPAK, while EC50 values of VTDTTR were lower compared with PKAPPAK and YIIEK. Transcriptomics analysis showed that 529 differentially expressed genes were identified in HEK-293T cells during the stimulating by VTDTTR and were mainly enriched into neuroactive ligand-receptor interaction, MAPK pathway, cAMP pathway and calcium signaling pathway, which were mainly responsible for the bitter signal transduction of VTDTTR. These results could provide evidence for understanding the bitter defects of dry-cured ham and the taste mechanism of bitter peptide.

The antidiabetic drug ipragliflozin induces vasorelaxation of rabbit femoral artery by activating a Kv channel, the SERCA pump, and the PKA signaling pathway

We explored the vasorelaxant effects of ipragliflozin, a sodium-glucose cotransporter-2 inhibitor, on rabbit femoral arterial rings. Ipragliflozin relaxed phenylephrine-induced pre-contracted rings in a dose-dependent manner. Pre-treatment with the ATP-sensitive K+ channel inhibitor glibenclamide (10 μM), the inwardly rectifying K+ channel inhibitor Ba2+ (50 μM), or the Ca2+-sensitive K+ channel inhibitor paxilline (10 μM) did not influence the vasorelaxant effect. However, the voltage-dependent K+ (Kv) channel inhibitor 4-aminopyridine (3 mM) reduced the vasorelaxant effect. Specifically, the vasorelaxant response to ipragliflozin was significantly attenuated by pretreatment with the Kv7.X channel inhibitors linopirdine (10 μM) and XE991 (10 μM), the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin (1 μM) and cyclopiazonic acid (10 μM), and the cAMP/protein kinase A (PKA)-associated signaling pathway inhibitors SQ22536 (50 μM) and KT5720 (1 μM). Neither the cGMP/protein kinase G (PKG)-associated signaling pathway nor the endothelium was involved in ipragliflozin-induced vasorelaxation. We conclude that ipragliflozin induced vasorelaxation of rabbit femoral arteries by activating Kv channels (principally the Kv7.X channel), the SERCA pump, and the cAMP/PKA-associated signaling pathway independent of other K+ (ATP-sensitive K+, inwardly rectifying K+, and Ca2+-sensitive K+) channels, cGMP/PKG-associated signaling, and the endothelium.

Identifying Phosphodiesterase-5 Inhibitors with Drug Repurposing Approach: Implications in Vasodysfunctional Disorders

Phosphodiesterase type 5 (PDE5) is a multidomain protein that plays a crucial role in regulating cellular cyclic guanosine monophosphate (cGMP), a key signaling molecule involved in various physiological processes. Dysregulation of PDE5 and cGMP signaling is associated with a range of vasodysfunctional disorders, necessitating the development of effective therapeutic interventions. This study adopts comprehensive approach, combining virtual screening and molecular dynamics (MD) simulations, to repurpose FDA-approved drugs as potential PDE5 inhibitors. The initial focus involves selecting compounds based on their binding affinity. Shortlisted compounds undergo a meticulous analysis for their drug profiling and biological significance, followed by the activity evaluation and interaction analysis. Notably, based on binding potential and drug profiling, two molecules, Dutasteride and Spironolactone, demonstrate strong potential as PDE5 inhibitors. Furthermore, all atom MD simulations were employed (500 ns) to explore dynamic behavior of Dutasteride and Spironolactone in complexes with PDE5. Principal components analysis (PCA) and free energy landscape (FEL) analyses are further leveraged to decipher that the binding of Dutasteride and Spironolactone stabilizes the structure of PDE5 with minimal conformational changes. In summary, Dutasteride and Spironolactone exhibit remarkable affinity for PDE5 and possess characteristics that suggest their potential as therapeutic agents for conditions associated with PDE5 dysfunction.

Association analysis of transcriptome and quasi-targeted metabolomics reveals the regulation mechanism underlying broiler muscle tissue development at different levels of dietary guanidinoacetic acid

The development and characteristics of muscle fibers in broilers are critical determinants that influence their growth performance, as well as serve as essential prerequisites for the production of high-quality chicken meat. Guanidinoacetic acid (GAA) is a crucial endogenous substance in animal creatine synthesis, and its utilization as a feed additive has been demonstrated the capabilities to enhance animal performance, optimize muscle yield, and augment carcass quality. The objective of this study was to investigate the regulation and molecular mechanism underlying muscle development in broilers at different levels of GAA via multiple omics analysis. The 90 Cobb broilers, aged 1 day, were randomly allocated into three treatments consisting of five replicates of six chickens each. The control group was provided with a basal diet, while the Normal GAA and High GAA groups received a basal diet supplemented with 1.2 g/kg and 3.6 g/kg of GAA, respectively. After a feeding period of 42 days, the pectoralis muscles were collected for histomorphological observation, transcriptome and metabolomic analysis. The results demonstrated that the addition of 1.2 g/kg GAA in the diet led to an augmentation in muscle fiber diameter and up-regulation of IGF1, IHH, ASB2, and ANKRD2 gene expression. However, a high dose of 3.6 g/kg GAA in the diet potentially reversed the beneficial effects on chicken breast development by excessively activating the TGF-β signaling pathway and reducing nucleotide metabolite content. These findings would provide a theoretical foundation for enhancing the performance and meat quality of broilers by incorporating GAA as a feed additive.

Extracellular nucleotides in smooth muscle contraction

Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules exert their effects by activating specific nucleotide receptors, which are finely regulated by ectonucleotidases that break down their ligands. In this comprehensive review, we aim to elucidate the relevance of extracellular nucleotides as signalling molecules in the context of smooth muscle contraction, considering the modulatory influence of ectonucleotidases on this intricate process. Specifically, we provide a detailed examination of the involvement of extracellular nucleotides in the contraction of non-vascular smooth muscles, including those found in the urinary bladder, the airways, the reproductive system, and the gastrointestinal tract. Furthermore, we present a broader overview of the role of extracellular nucleotides in vascular smooth muscle contraction.

Phosphodiesterases Mediate the Augmentation of Myogenic Constriction by Inhibitory G Protein Signaling and is Negatively Modulated by the Dual Action of RGS2 and 5

G protein regulation by regulators of G protein signaling (RGS) proteins play a key role in vascular tone maintenance. The loss of Gi/o and Gq/11 regulation by RGS2 and RGS5 in non-pregnant mice is implicated in augmented vascular tone and decreased uterine blood flow (UBF). RGS2 and 5 are closely related and co-expressed in uterine arteries (UA). However, whether and how RGS2 and 5 coordinate their regulatory activities to finetune G protein signaling and regulate vascular tone are unclear. Here, we determined how the integrated activity of RGS2 and 5 modulates vascular tone to promote UBF. Using ultrasonography and pressure myography, we examined uterine hemodynamics and myogenic tone (MT) of UA of wild type (WT), Rgs2-/-, Rgs5-/-, and Rgs2/5 dbKO mice. We found that MT was reduced in Rgs5-/- relative to WT or Rgs2-/- UA. Activating Gi/o with dopamine increased, whereas exogenous cAMP decreased MT in Rgs5-/- UA to levels in WT UA. Dual deletion of Rgs2 and 5 abolished the reduced MT due to the absence of Rgs5 and enhanced dopamine-induced Gi/o effects in Rgs2/5 dbKO UA. Conversely, and as in WT UA, Gi/o inhibition with pertussis toxin or exogenous cAMP decreased MT in Rgs2/5 dbKO to levels in Rgs5-/- UA. Inhibition of phosphodiesterases (PDE) concentration-dependently decreased and normalized MT in all genotypes, and blocked dopamine-induced MT augmentation in Rgs2-/-, Rgs5-/-, and Rgs2/5 dbKO UA. We conclude that Gi/o augments UA MT in the absence of RGS2 by a novel mechanism involving PDE-mediated inhibition of cAMP-dependent vasodilatation..

Recent insights into mechanisms of hypoxia-induced vasodilatation in the human brain

The cerebral vasculature manages oxygen delivery by adjusting arterial blood in-flow in the face of reductions in oxygen availability. Hypoxic cerebral vasodilatation, and the associated hypoxic cerebral blood flow reactivity, involve many vascular, erythrocytic and cerebral tissue mechanisms that mediate elevations in cerebral blood flow via micro- and macrovascular dilatation. This contemporary review focuses on in vivo human work - with reference to seminal preclinical work where necessary - on hypoxic cerebrovascular reactivity, particularly where recent advancements have been made. We provide updates with the following information: in humans, hypoxic cerebral vasodilatation is partially mediated via a - likely non-obligatory - combination of: (1) nitric oxide synthases, (2) deoxygenation-coupled S-nitrosothiols, (3) potassium channel-related vascular smooth muscle hyperpolarization, and (4) prostaglandin mechanisms with some contribution from an interrelationship with reactive oxygen species. And finally, we discuss the fact that, due to the engagement of deoxyhaemoglobin-related mechanisms, reductions in O2 content via haemoglobin per se seem to account for ∼50% of that seen with hypoxic cerebral vasodilatation during hypoxaemia. We further highlight the issue that methodological impediments challenge the complete elucidation of hypoxic cerebral reactivity mechanisms in vivo in healthy humans. Future research is needed to confirm recent advancements and to reconcile human and animal findings. Further investigations are also required to extend these findings to address questions of sex-, heredity-, age-, and disease-related differences. The final step is to then ultimately translate understanding of these mechanisms into actionable, targetable pathways for the prevention and treatment of cerebral vascular dysfunction and cerebral hypoxic brain injury.

Regulation of the renin-angiotensin-aldosterone system by cyclic nucleotides and phosphodiesterases

The renin-angiotensin-aldosterone system (RAAS) is one of the key players in the regulation of blood volume and blood pressure. Dysfunction of this system is connected with cardiovascular and renal diseases. Regulation of RAAS is under the control of multiple intracellular mechanisms. Cyclic nucleotides and phosphodiesterases are the major regulators of this system since they control expression and activity of renin and aldosterone. In this review, we summarize known mechanisms by which cyclic nucleotides and phosphodiesterases regulate renin gene expression, secretion of renin granules from juxtaglomerular cells and aldosterone production from zona glomerulosa cells of adrenal gland. We also discuss several open questions which deserve future attention.

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.

FP and EP2 prostanoid receptor agonist drugs and aqueous humor outflow devices for treating ocular hypertension and glaucoma

Prostaglandin (PG) receptors represent important druggable targets due to the many diverse actions of PGs in the body. From an ocular perspective, the discovery, development, and health agency approvals of prostaglandin F (FP) receptor agonists (FPAs) have revolutionized the medical treatment of ocular hypertension (OHT) and glaucoma. FPAs, such as latanoprost, travoprost, bimatoprost, and tafluprost, powerfully lower and control intraocular pressure (IOP), and became first-line therapeutics to treat this leading cause of blindness in the late 1990s to early 2000s. More recently, a latanoprost-nitric oxide (NO) donor conjugate, latanoprostene bunod, and a novel FP/EP3 receptor dual agonist, sepetaprost (ONO-9054 or DE-126), have also demonstrated robust IOP-reducing activity. Moreover, a selective non-PG prostanoid EP2 receptor agonist, omidenepag isopropyl (OMDI), was discovered, characterized, and has been approved in the United States, Japan and several other Asian countries for treating OHT/glaucoma. FPAs primarily enhance uveoscleral (UVSC) outflow of aqueous humor (AQH) to reduce IOP, but cause darkening of the iris and periorbital skin, uneven thickening and elongation of eyelashes, and deepening of the upper eyelid sulcus during chronic treatment. In contrast, OMDI lowers and controls IOP by activation of both the UVSC and trabecular meshwork outflow pathways, and it has a lower propensity to induce the aforementioned FPA-induced ocular side effects. Another means to address OHT is to physically promote the drainage of the AQH from the anterior chamber of the eye of patients with OHT/glaucoma. This has successfully been achieved by the recent approval and introduction of miniature devices into the anterior chamber by minimally invasive glaucoma surgeries. This review covers the three major aspects mentioned above to highlight the etiology of OHT/glaucoma, and the pharmacotherapeutics and devices that can be used to combat this blinding ocular disease.

Effects of bisphenol A on human umbilical arteries

Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in the plastics industry, including food container, toys, and medical equipment. We analyzed the effect of BPA in human umbilical artery contractility and expression of some proteins modulating this function, such as ionic channels and proteins involved in the cGMP pathway. Using standard organ bath technique, rings of human umbilical arteries without endothelium were contracted by 5-HT (1 μM) and histamine (10 μM) and the effect of different concentrations of BPA (1 nM-100 μM) was analyzed. The results showed that BPA is a vasodilator of these arteries in a concentration-dependent way. Besides, qPCR studies on human umbilical smooth muscle cells (HUSMC) allowed to analyze the effects of BPA on gene expression. Thus, 12-h exposition to BPA induced reduction of expression of L-type calcium channels (LTCC), alpha subunit of BK_Ca channels, and Kvβ1 and Kvβ3 from Kv channels. BPA also decreased the expression of soluble guanylate cyclase (sGC) and natriuretic peptide receptor type A (NPRA), meanwhile increasing that of PKG, proteins involved in vasodilation of human umbilical arteries (HUA) by cGMP. Further studies will be necessary to increase knowledge about the implications of these changes induced by BPA exposure.

Impaired Platelet Function and Thrombus Formation in PDE5A-Deficient Mice

Intracellular cyclic GMP (cGMP) inhibits platelet function. Platelet cGMP levels are controlled by phosphodiesterase 5A (PDE5A)-mediated degradation. However, the exact role of PDE5A in platelet function and thrombus formation remains poorly understood. In this study, we characterized the role of PDE5A in platelet activation and function. Platelets were isolated from wild type or PDE5A^-/- mice to measure platelet aggregation, activation, phosphatidylserine exposure (annexin-V binding), reactive oxygen species (ROS) generation, platelet spreading as well as clot retraction. Cytosolic calcium mobilization was measured using Fluo-4 AM by a microplate reader. Western blot was used to measure the phosphorylation of VASP, ERK1/2, p38, JNK, and AKT. FeCl₃-induced arterial thrombosis and venous thrombosis were assessed to evaluate the in vivo hemostatic function and thrombus formation. Additionally, in vitro thrombus formation was assessed in a microfluidic whole-blood perfusion assay. PDE5A-deficient mice presented significantly prolonged tail bleeding time and delayed arterial and venous thrombus formation. PDE5A deficiency significantly inhibited platelet aggregation, ATP release, P-selectin expression, and integrin aIIbb3 activation. In addition, an impaired spreading on collagen or fibrinogen and clot retraction was observed in PDE5A-deficient platelets. Moreover, PDE5A deficiency reduced phosphatidylserine exposure, calcium mobilization, ROS production, and increased intracellular cGMP level along with elevated VASP phosphorylation and reduced phosphorylation of ERK1/2, p38, JNK, and AKT. In conclusion, PDE5A modulates platelet activation and function and thrombus formation, indicating that therapeutically targeting it might be beneficial for the treatment of thrombotic diseases.

Redox-Regulation of α-Globin in Vascular Physiology

Interest in the structure, function, and evolutionary relations of circulating and intracellular globins dates back more than 60 years to the first determination of the three-dimensional structure of these proteins. Non-erythrocytic globins have been implicated in circulatory control through reactions that couple nitric oxide (NO) signaling with cellular oxygen availability and redox status. Small artery endothelial cells (ECs) express free α-globin, which causes vasoconstriction by degrading NO. This reaction converts reduced (Fe2+) α-globin to the oxidized (Fe3+) form, which is unstable, cytotoxic, and unable to degrade NO. Therefore, (Fe3+) α-globin must be stabilized and recycled to (Fe2+) α-globin to reinitiate the catalytic cycle. The molecular chaperone α-hemoglobin-stabilizing protein (AHSP) binds (Fe3+) α-globin to inhibit its degradation and facilitate its reduction. The mechanisms that reduce (Fe3+) α-globin in ECs are unknown, although endothelial nitric oxide synthase (eNOS) and cytochrome b5 reductase (CyB5R3) with cytochrome b5 type A (CyB5a) can reduce (Fe3+) α-globin in solution. Here, we examine the expression and cellular localization of eNOS, CyB5a, and CyB5R3 in mouse arterial ECs and show that α-globin can be reduced by either of two independent redox systems, CyB5R3/CyB5a and eNOS. Together, our findings provide new insights into the regulation of blood vessel contractility.

Evolution of the membrane/particulate guanylyl cyclase: From physicochemical sensors to hormone receptors

Guanylyl cyclase (GC) is an enzyme that produces 3',5'-cyclic guanosine monophosphate (cGMP), one of the two canonical cyclic nucleotides used as a second messenger for intracellular signal transduction. The GCs are classified into two groups, particulate/membrane GCs (pGC) and soluble/cytosolic GCs (sGC). In relation to the endocrine system, pGCs include hormone receptors for natriuretic peptides (GC-A and GC-B) and guanylin peptides (GC-C), while sGC is a receptor for nitric oxide and carbon monoxide. Comparing the functions of pGCs in eukaryotes, it is apparent that pGCs perceive various environmental factors such as light, temperature, and various external chemical signals in addition to endocrine hormones, and transmit the information into the cell using the intracellular signaling cascade initiated by cGMP, e.g., cGMP-dependent protein kinases, cGMP-sensitive cyclic nucleotide-gated ion channels and cGMP-regulated phosphodiesterases. Among vertebrate pGCs, GC-E and GC-F are localized on retinal epithelia and are involved in modifying signal transduction from the photoreceptor, rhodopsin. GC-D and GC-G are localized in olfactory epithelia and serve as sensors at the extracellular domain for external chemical signals such as odorants and pheromones. GC-G also responds to guanylin peptides in the urine, which alters sensitivity to other chemicals. In addition, guanylin peptides that are secreted into the intestinal lumen, a pseudo-external environment, act on the GC-C on the apical membrane for regulation of epithelial transport. In this context, GC-C and GC-G appear to be in transition from exocrine pheromone receptor to endocrine hormone receptor. The pGCs also exist in various deuterostome and protostome invertebrates, and act as receptors for environmental, exocrine and endocrine factors including hormones. Tracing the evolutionary history of pGCs, it appears that pGCs first appeared as a sensor for physicochemical signals in the environment, and then evolved to function as hormone receptors. In this review, the author proposes an evolutionary history of pGCs that highlights the emerging role of the GC/cGMP system for signal transduction in hormone action.

Regulation of myosin light-chain phosphorylation and its roles in cardiovascular physiology and pathophysiology

The regulation of muscle contraction is a critical function in the cardiovascular system, and abnormalities may be life-threatening or cause illness. The common basic mechanism in muscle contraction is the interaction between the protein filaments myosin and actin. Although this interaction is primarily regulated by intracellular Ca²⁺, the primary targets and intracellular signaling pathways differ in vascular smooth muscle and cardiac muscle. Phosphorylation of the myosin regulatory light chain (RLC) is a primary molecular switch for smooth muscle contraction. The equilibrium between phosphorylated and unphosphorylated RLC is dynamically achieved through two enzymes, myosin light chain kinase, a Ca²⁺-dependent enzyme, and myosin phosphatase, which modifies the Ca²⁺ sensitivity of contractions. In cardiac muscle, the primary target protein for Ca²⁺ is troponin C on thin filaments; however, RLC phosphorylation also plays a modulatory role in contraction. This review summarizes recent advances in our understanding of the regulation, physiological function, and pathophysiological involvement of RLC phosphorylation in smooth and cardiac muscles.

PDE-Mediated Cyclic Nucleotide Compartmentation in Vascular Smooth Muscle Cells: From Basic to a Clinical Perspective

Cardiovascular diseases are important causes of mortality and morbidity worldwide. Vascular smooth muscle cells (SMCs) are major components of blood vessels and are involved in physiologic and pathophysiologic conditions. In healthy vessels, vascular SMCs contribute to vasotone and regulate blood flow by cyclic nucleotide intracellular pathways. However, vascular SMCs lose their contractile phenotype under pathological conditions and alter contractility or signalling mechanisms, including cyclic nucleotide compartmentation. In the present review, we focus on compartmentalized signaling of cyclic nucleotides in vascular smooth muscle. A deeper understanding of these mechanisms clarifies the most relevant axes for the regulation of vascular tone. Furthermore, this allows the detection of possible changes associated with pathological processes, which may be of help for the discovery of novel drugs.

Fetoplacental vasculature as a model to study human cardiovascular endocrine disruption

Increasing evidence has associated the exposure of endocrine-disrupting chemicals (EDCs) with the cardiovascular (CV) system. This exposure is particularly problematic in a sensitive window of development, pregnancy. Pregnancy exposome can affect the overall health of the pregnancy by dramatic changes in vascular physiology and endocrine activity, increasing maternal susceptibility. Moreover, fetoplacental vascular function is generally altered, increasing the risk of developing pregnancy complications (including cardiovascular diseases, CVD) and predisposing the foetus to adverse health risks later in life. Thus, our review summarizes the existing literature on exposures to EDCs during pregnancy and adverse maternal health outcomes, focusing on the human placenta, vein, and umbilical artery associated with pregnancy complications. The purpose of this review is to highlight the role of fetoplacental vasculature as a model for the study of human cardiovascular endocrine disruption. Therefore, we emphasize that the placenta, together with the umbilical arteries and veins, allows a better characterization of the pregnant woman's exposome. Consequently, it contributes to the protection of the mother and foetus against CV disorders in life.

Genetic investigation of fibromuscular dysplasia identifies risk loci and shared genetics with common cardiovascular diseases

Fibromuscular dysplasia (FMD) is an arteriopathy associated with hypertension, stroke and myocardial infarction, affecting mostly women. We report results from the first genome-wide association meta-analysis of six studies including 1556 FMD cases and 7100 controls. We find an estimate of SNP-based heritability compatible with FMD having a polygenic basis, and report four robustly associated loci (PHACTR1, LRP1, ATP2B1, and LIMA1). Transcriptome-wide association analysis in arteries identifies one additional locus (SLC24A3). We characterize open chromatin in arterial primary cells and find that FMD associated variants are located in arterial-specific regulatory elements. Target genes are broadly involved in mechanisms related to actin cytoskeleton and intracellular calcium homeostasis, central to vascular contraction. We find significant genetic overlap between FMD and more common cardiovascular diseases and traits including blood pressure, migraine, intracranial aneurysm, and coronary artery disease.

Cyclic nucleotide phosphodiesterase inhibition as a potential therapeutic target in renal ischemia reperfusion injury

AIMS

Ischemia/reperfusion (I/R) occurs in renal artery stenosis, partial nephrectomy and most commonly during kidney transplantation. It brings serious consequences such as DGF (Delayed Graft Function) or organ dysfunction leading to renal failure and ultimate death. There is no effective therapy to handle the consequences of Renal Ischemia/Reperfusion (I/R) injury. Cyclic nucleotides, cAMP and cGMP are the important second messengers that stimulate intracellular signal transduction for cell survival in response to growth factors and peptide hormones in normal tissues and in kidneys plays significant role that involves vascular tone regulation, inflammation and proliferation of parenchymal cells. Renal ischemia and subsequent reperfusion injury stimulate signal transduction pathways involved in oxidative stress, inflammation, alteration in renal blood flow leading to necrosis and apoptosis of renal cell.

MATERIALS AND METHODS

An extensive literature review of various search engines like PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out. To understand the functioning of Phosphodiesterases (PDEs) and its pharmacological modulation in Renal Ischemia-Reperfusion Injury.

KEY FINDINGS

Current therapeutic options may not be enough to treat renal I/R injury in group of patients and therefore, the current review has discussed the general characteristics and physiology of PDEs and preclinical-studies defining the relationship between PDEs expression in renal injury due to I/R and its outcome on renal function.

SIGNIFICANCE

The role of PDE inhibitors in renal I/R injury and the clinical status of drugs for various renal diseases have been summarized in this review.

Protective Effect of Nicorandil on Cardiac Microvascular Injury: Role of Mitochondrial Integrity

A major shortcoming of postischemic therapy for myocardial infarction is the no-reflow phenomenon due to impaired cardiac microvascular function including microcirculatory barrier function, loss of endothelial activity, local inflammatory cell accumulation, and increased oxidative stress. Consequently, inadequate reperfusion of the microcirculation causes secondary ischemia, aggravating the myocardial reperfusion injury. ATP-sensitive potassium ion (KATP) channels regulate the coronary blood flow and protect cardiomyocytes from ischemia-reperfusion injury. Studies in animal models of myocardial ischemia-reperfusion have illustrated that the opening of mitochondrial KATP (mito-KATP) channels alleviates endothelial dysfunction and reduces myocardial necrosis. By contrast, blocking mito-KATP channels aggravates microvascular necrosis and no-reflow phenomenon following ischemia-reperfusion injury. Nicorandil, as an antianginal drug, has been used for ischemic preconditioning (IPC) due to its mito-KATP channel-opening effect, thereby limiting infarct size and subsequent severe ischemic insult. In this review, we analyze the protective actions of nicorandil against microcirculation reperfusion injury with a focus on improving mitochondrial integrity. In addition, we discuss the function of mitochondria in the pathogenesis of myocardial ischemia.

Myorelaxant Effect of the Dysphania ambrosioides Essential Oil on Sus scrofa domesticus Coronary Artery and Its Toxicity in the Drosophila melanogaster Model

PURPOSE

Alternative methods for the use of animals in research have gained increasing importance, due to assessments evaluating the real need for their use and the development of legislation that regulates the subject. The principle of the 3R's (replacement, reduction and refinement) has been an important reference, such that in vitro, ex vivo and cord replacement methods have achieved a prominent place in research.

METHODS

Therefore, due to successful results from studies developed with these methods, the present study aimed to evaluate the myorelaxant effect of the Dysphania ambrosioides essential oil (EODa) using a Sus scrofa domesticus coronary artery model, and the toxicity of both the Dysphania ambrosioides essential oil and its major constituent, α-terpinene, against Drosophila melanogaster in toxicity and negative geotaxis assays.

RESULTS

The EODa relaxed the smooth muscle of swine coronary arteries precontracted with K⁺ and 5-HT in assays using Sus scrofa domesticus coronary arteries. The toxicity results presented LC₅₀ values of 1.546 mg/mL and 2.282 mg/mL for the EODa and α-terpinene, respectively, thus showing the EODa and α-terpinene presented toxicity to these dipterans, with the EODa being more toxic.

CONCLUSIONS

Moreover, the results reveal the possibility of using the EODa in vascular disease studies since it promoted the relaxation of the Sus scrofa domesticus coronary smooth muscle.

Construction of circRNA-miRNA-mRNA Network for Exploring Underlying Mechanisms of Lubrication Disorder

Lubrication disorder is a common health issue that manifests as insufficient sexual arousal at the beginning of sex. It often causes physical and psychological distress. However, there are few studies on lubrication disorder, and the complexity of circular RNA (circRNA) and the related competing endogenous RNA (ceRNA) network in lubrication disorder is still poorly known. Therefore, this study aims to build a regulatory circRNA-micro (mi)RNA-mRNA network and explore potential molecular markers of lubrication disorder. In the study, 12 subjects were recruited, including 6 in the lubrication disorder group and 6 in the normal control group. RNA sequencing was exploited to identify the expression profiles of circRNA, miRNA and mRNA between two groups, and then to construct the circRNA-miRNA-mRNA networks. The enrichment analyses of the differentially expressed (DE)-mRNAs were examined via Gene Set Enrichment Analysis (GSEA). Furthermore, the expression level and interactions among circRNA, miRNA, and mRNA were validated using real-time quantitative polymerase chain reaction (RT-qPCR) and dual-luciferase reporter assays. In the results, 73 circRNAs, 287 miRNAs, and 354 target mRNAs were differentially expressed between two groups when taking | Log2 (fold change)| > 1 and P-value < 0.05 as criteria, and then the results of GSEA revealed that DE-mRNAs were linked with "vascular smooth muscle contraction," "aldosterone regulated sodium reabsorption," "calcium signaling pathway," etc. 19 target relationships among 5 circRNAs, 4 miRNAs, and 7 mRNAs were found and constructed the ceRNA network. Among them, hsa-miR-212-5p and hsa-miR-874-3p were demonstrated to be related to the occurrence of lubrication disorder. Eventually, consistent with sequencing, RT-qPCR showed that hsa_circ_0026782 and ASB2 were upregulated while hsa-miR-874-3p was downregulated, and dual-luciferase reporter assays confirmed the interactions among them. In summary, the findings indicate that the circRNA-miRNA-mRNA regulatory network is presented in lubrication disorder, and ulteriorly provide a deeper understanding of the specific regulatory mechanism of lubrication disorder from the perspective of the circRNA-miRNA-mRNA network.

PGE2 receptors in detrusor muscle: Drugging the undruggable for urgency

Overactive bladder (OAB) syndrome is a prevalent condition of the lower urinary tract that causes symptoms, such as urinary frequency, urinary urgency, urge incontinence, and nocturia, and disproportionately affects women and the elderly. Current medications for OAB merely provide symptomatic relief with considerable limitations, as they are no more than moderately effective, not to mention that they may cause substantial adverse effects. Identifying novel molecular targets to facilitate the development of new medical therapies with higher efficacy and safety for OAB is in an urgent unmet need. Although the molecular mechanisms underlying the pathophysiology of OAB largely remain elusive and are likely multifactorial, mounting evidence from preclinical studies over the past decade reveals that the pro-inflammatory pathways engaging cyclooxygenases and their prostanoid products, particularly the prostaglandin E2 (PGE₂), may play essential roles in the progression of OAB. The goals of this review are to summarize recent progresses in our knowledge on the pathogenic roles of PGE₂ in the OAB and to provide new mechanistic insights into the signaling pathways transduced by its four G-protein-coupled receptors (GPCRs), i.e., EP1-EP4, in the overactive detrusor smooth muscle. We also discuss the feasibility of targeting these GPCRs as an emerging strategy to treat OAB with better therapeutic specificity than the current medications.

Hypertension is associated with blunted NO-mediated leg vasodilator responsiveness that is reversed by high-intensity training in postmenopausal women

The menopausal transition is associated with increased prevalence of hypertension, and in time, postmenopausal women (PMW) will exhibit a cardiovascular disease risk score similar to male counterparts. Hypertension is associated with vascular dysfunction, but whether hypertensive (HYP) PMW have blunted nitric oxide (NO)-mediated leg vasodilator responsiveness and whether this is reversible by high-intensity training (HIT) is unknown. To address these questions, we examined the leg vascular conductance (LVC) in response to femoral infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) and skeletal muscle markers of oxidative stress and NO bioavailability before and after HIT in PMW [12.9 ± 6.0 (means ± SD) years since last menstrual cycle]. We hypothesized that ACh- and SNP-induced LVC responsiveness was reduced in hypertensive compared with normotensive (NORM) PMW and that 10 wk of HIT would reverse the blunted LVC response and decrease blood pressure (BP). Nine hypertensive (HYP (clinical systolic/diastolic BP, 149 ± 11/91 ± 83 mmHg) and eight normotensive (NORM (122 ± 13/75 ± 8 mmHg) PMW completed 10 wk of biweekly small-sided floorball training (4-5 × 3-5 min interspersed by 1-3-min rest periods). Before training, the SNP-induced change in LVC was lower (P < 0.05) in HYP compared with in NORM. With training, the ACh- and SNP-induced change in LVC at maximal infusion rates, i.e., 100 and 6 µg·min^-1·kg leg mass^-1, respectively, improved (P < 0.05) in HYP only. Furthermore, training decreased (P < 0.05) clinical systolic/diastolic BP (-15 ± 11/-9 ± 7 mmHg) in HYP and systolic BP (-10 ± 9 mmHg) in NORM. Thus, the SNP-mediated LVC responsiveness was blunted in HYP PMW and reversed by a period of HIT that was associated with a marked decrease in clinical BP.

Therapeutic Implications for PDE2 and cGMP/cAMP Mediated Crosstalk in Cardiovascular Diseases

Phosphodiesterases (PDEs) are the principal superfamily of enzymes responsible for degrading the secondary messengers 3',5'-cyclic nucleotides cAMP and cGMP. Their refined subcellular localization and substrate specificity contribute to finely regulate cAMP/cGMP gradients in various cellular microdomains. Redistribution of multiple signal compartmentalization components is often perceived under pathological conditions. Thereby PDEs have long been pursued as therapeutic targets in diverse disease conditions including neurological, metabolic, cancer and autoimmune disorders in addition to numerous cardiovascular diseases (CVDs). PDE2 is a unique member of the broad family of PDEs. In addition to its capability to hydrolyze both cAMP and cGMP, PDE2 is the sole isoform that may be allosterically activated by cGMP increasing its cAMP hydrolyzing activity. Within the cardiovascular system, PDE2 serves as an integral regulator for the crosstalk between cAMP/cGMP pathways and thereby may couple chronically adverse augmented cAMP signaling with cardioprotective cGMP signaling. This review provides a comprehensive overview of PDE2 regulatory functions in multiple cellular components within the cardiovascular system and also within various subcellular microdomains. Implications for PDE2- mediated crosstalk mechanisms in diverse cardiovascular pathologies are discussed highlighting the prospective use of PDE2 as a potential therapeutic target in cardiovascular disorders.

Phylogenic Determinants of Cardiovascular Frailty, Focus on Hemodynamics and Arterial Smooth Muscle Cells

The evolution of the circulatory system from invertebrates to mammals has involved the passage from an open system to a closed in-parallel system via a closed in-series system, accompanying the increasing complexity and efficiency of life’s biological functions. The archaic heart enables pulsatile motion waves of hemolymph in invertebrates, and the in-series circulation in fish occurs with only an endothelium, whereas mural smooth muscle cells appear later. The present review focuses on evolution of the circulatory system. In particular, we address how and why this evolution took place from a closed, flowing, longitudinal conductance at low pressure to a flowing, highly pressurized and bifurcating arterial compartment. However, although arterial pressure was the latest acquired hemodynamic variable, the general teleonomy of the evolution of species is the differentiation of individual organ function, supported by specific fueling allowing and favoring partial metabolic autonomy. This was achieved via the establishment of an active contractile tone in resistance arteries, which permitted the regulation of blood supply to specific organ activities via its localized function-dependent inhibition (active vasodilation). The global resistance to viscous blood flow is the peripheral increase in frictional forces caused by the tonic change in arterial and arteriolar radius, which backscatter as systemic arterial blood pressure. Consequently, the arterial pressure gradient from circulating blood to the adventitial interstitium generates the unidirectional outward radial advective conductance of plasma solutes across the wall of conductance arteries. This hemodynamic evolution was accompanied by important changes in arterial wall structure, supported by smooth muscle cell functional plasticity, including contractility, matrix synthesis and proliferation, endocytosis and phagocytosis, etc. These adaptive phenotypic shifts are due to epigenetic regulation, mainly related to mechanotransduction. These paradigms actively participate in cardio-arterial pathologies such as atheroma, valve disease, heart failure, aneurysms, hypertension, and physiological aging.

Muscarinic-dependent phosphorylation of the cardiac ryanodine receptor by protein kinase G is mediated by PI3K-AKT-nNOS signaling

Post-translational modifications of proteins involved in calcium handling in myocytes, such as the cardiac ryanodine receptor (RyR2), critically regulate cardiac contractility. Recent studies have suggested that phosphorylation of RyR2 by protein kinase G (PKG) might contribute to the cardioprotective effects of cholinergic stimulation. However, the specific mechanisms underlying these effects remain unclear. Here, using murine ventricular myocytes, immunoblotting, proximity ligation as-says, and nitric oxide imaging, we report that phosphorylation of Ser-2808 in RyR2 induced by the muscarinic receptor agonist carbachol is mediated by a signaling axis comprising phosphoinositide 3-phosphate kinase, Akt Ser/Thr kinase, nitric oxide synthase 1, nitric oxide, soluble guanylate cyclase, cyclic GMP (cGMP), and PKG. We found that this signaling pathway is compartmentalized in myocytes, as it was distinct from atrial natriuretic peptide receptor-cGMP-PKG-RyR2 Ser-2808 signaling and independent of muscarinic-induced phosphorylation of Ser-239 in vasodilator-stimulated phosphoprotein. These results provide detailed insights into muscarinic-induced PKG signaling and the mediators that regulate cardiac RyR2 phosphorylation critical for cardiovascular function.

Interplay of transcriptional signaling by progesterone, cyclic AMP, and inflammation in myometrial cells: implications for the control of human parturition

Parturition involves cellular signaling changes driven by the complex interplay between progesterone (P4), inflammation, and the cyclic adenosine monophosphate (cAMP) pathway. To characterize this interplay, we performed comprehensive transcriptomic studies utilizing eight treatment combinations on myometrial cell lines and tissue samples from pregnant women. We performed genome-wide RNA-sequencing on the hTERT-HM${}^{A/B}$ cell line treated with all combinations of P4, forskolin (FSK) (induces cAMP), and interleukin-1$\beta$ (IL-1$\beta$). We then performed gene set enrichment and regulatory network analyses to identify pathways commonly, differentially, or synergistically regulated by these treatments. Finally, we used tissue similarity index (TSI) to characterize the correspondence between cell lines and tissue phenotypes. We observed that in addition to their individual anti-inflammatory effects, P4 and cAMP synergistically blocked specific inflammatory pathways/regulators including STAT3/6, CEBPA/B, and OCT1/7, but not NF$\kappa$B. TSI analysis indicated that FSK + P4- and IL-1$\beta$-treated cells exhibit transcriptional signatures highly similar to non-laboring and laboring term myometrium, respectively. Our results identify potential therapeutic targets to prevent preterm birth and show that the hTERT-HM${}^{A/B}$ cell line provides an accurate transcriptional model for term myometrial tissue.

Essential hypertension is associated with blunted smooth muscle cell vasodilator responsiveness and is reversed by 10-20-30 training in men

Essential hypertension is associated with impairments in vascular function and sympathetic nerve hyperactivity; however, the extent to which the lower limbs are affected remains unclear. We examined the leg vascular responsiveness to infusion of acetylcholine (ACh), sodium nitroprusside (SNP), and phenylephrine (PEP) in 10 hypertensive men [HYP: age 59.5 ± 9.7 (means ± SD) yr; clinical and nighttime blood pressure: 142 ± 10/86 ± 10 and 141 ± 11/83 ± 6 mmHg, respectively; and body mass index (BMI): 29.2 ± 4.0 kg/m2] and 8 age-matched normotensive counterparts (NORM: age 57.9 ± 10.8 yr; clinical and nighttime blood pressure: 128 ± 9/78 ± 7 and 116 ± 3/69 ± 3 mmHg, respectively; and BMI: 26.3 ± 3.1 kg/m2). The vascular responsiveness was evaluated before and after 6 wk of 10-20-30 training, consisting of 3 × 5 × 10-s sprint followed by 30 and 20 s of low- to moderate-intensity cycling, respectively, interspersed by 3 min of rest. Before training, the vascular responsiveness to infusion of SNP was lower ( P < 0.05) in HYP compared with NORM, with no difference in the responsiveness to infusion of ACh and PEP. The vascular responsiveness to infusion of SNP and ACh improved ( P < 0.05) with training in HYP, with no change in NORM. With training, intra-arterial systolic blood pressure decreased ( P < 0.05) by 9 mmHg in both HYP and NORM whereas diastolic blood pressure decreased (5 mmHg; P < 0.05) in HYP only. We provide here the first line of evidence in humans that smooth muscle cell vasodilator responsiveness is blunted in the lower limbs of hypertensive men. This impairment can be reversed by 10-20-30 training, which is an effective intervention to improve the responsiveness of smooth muscle cells in men with essential hypertension.

Differential modulation of endothelial cell function by fresh frozen plasma

AIMS

In vivo studies suggest a positive influence of fresh frozen plasma (FFP) on endothelial properties and vascular barrier function, leading to improved outcomes in animal sepsis models as well as in major abdominal surgery. However, those effects are incompletely described. It was our aim to evaluate in vitro effects of FFP on endothelial key functions and to identify underlying mechanisms.

MATERIALS AND METHODS

Human pulmonary microvascular endothelial cells (HPMECs) were prestimulated with LPS, followed by incubation with FFP. Permeability for FITC-dextran was assessed, and intercellular gap formation was visualized. NF-κB nuclear translocation and expression of pro-inflammatory, pro-adhesion, and leakage-related genes were evaluated, and monocyte adhesion to ECs was assessed. Intracellular cAMP levels as well as phosphorylation of functional proteins were analyzed. In patients undergoing major abdominal surgery, Syndecan-1 serum levels were assessed prior to and following FFP transfusion.

KEY FINDINGS

Post-incubation of HPMVECs with FFP increased intracellular cAMP levels that had been decreased by preceding LPS stimulation. On one hand, this reduced endotoxin-mediated upregulation of IL-8, ICAM-1, VCAM-1, VEGF, and ANG-2. Impaired phosphorylation of functional proteins was restored, and intercellular cohesion and barrier function were rescued. On the other hand, NF-κB nuclear translocation as well as monocyte adhesion was markedly increased by the combination of LPS and FFP. Syndecan-1 serum levels were lower in surgery patients that were transfused with FFP compared to those that were not.

SIGNIFICANCE

Our data provide evidence for a differential modulation of crucial endothelial properties by FFP, potentially mediated by elevation of intracellular cAMP levels.

The role of semen and seminal plasma in inducing large-scale genomic changes in the female porcine peri-ovulatory tract

Semen modifies the expression of genes related to immune function along the porcine female internal genital tract. Whether other pathways are induced by the deposition of spermatozoa and/or seminal plasma (SP), is yet undocumented. Here, to determine their relative impact on the uterine and tubal transcriptomes, microarray analyses were performed on the endocervix, endometrium and endosalpinx collected from pre-ovulatory sows 24 h after either mating or artificial insemination (AI) with specific ejaculate fractions containing spermatozoa or sperm-free SP. After enrichment analysis, we found an overrepresentation of genes and pathways associated with sperm transport and binding, oxidative stress and cell-to-cell recognition, such as PI3K-Akt, FoxO signaling, glycosaminoglycan biosynthesis and cAMP-related transcripts, among others. Although semen (either after mating or AI) seemed to have the highest impact along the entire genital tract, our results demonstrate that the SP itself also modifies the transcriptome. The detected modifications of the molecular profiles of the pre/peri-ovulatory endometrium and endosalpinx suggest an interplay for the survival, transport and binding of spermatozoa through, for instance the up-regulation of the Estrogen signaling pathway associated with attachment and release from the oviductal reservoir.

Intrauterine growth restriction is associated with sex-specific alterations in the nitric oxide/cyclic GMP relaxing pathway in the human umbilical vein

INTRODUCTION

Intrauterine growth restriction (IUGR) is a leading cause of perinatal mortality and morbidity, and is linked to an increased risk to develop chronic diseases in adulthood. We previously demonstrated that IUGR is associated, in female neonates, with a decreased nitric oxide (NO)-induced relaxation of the umbilical vein (UV). The present study aimed to investigate the contribution of the smooth muscle components of the NO/cyclic GMP (cGMP) pathway to this alteration.

METHODS

UVs were collected in growth-restricted or appropriate for gestational age (AGA) human term newborns. Soluble guanylyl cyclase (sGC) and cGMP-dependent protein kinase (PKG) were studied by Western blot, cGMP production by ELISA and cyclic nucleotide phosphodiesterases (PDEs) activity using a colorimetric assay. Contribution of PDEs was evaluated using the non-specific PDEs inhibitor 3-isobutyl-1-methylxanthine (IBMX) in isolated vessel tension studies.

RESULTS

NO-induced relaxation was reduced in IUGR females despite increased sGC protein and activity, and some increase in PKG protein compared to AGA. In males, no significant difference was observed between both groups. In the presence of IBMX, NO-stimulated cGMP production was significantly higher in IUGR than AGA females. Pre-incubation with IBMX significantly improved NO-induced relaxation in all groups and abolished the difference between IUGR and AGA females.

CONCLUSION

IUGR is associated with sex-specific alterations in the UV's smooth muscle. The impaired NO-induced relaxation observed in growth-restricted females is linked to an imbalance in the NO/cGMP pathway. The beneficial effects of IBMX suggest that PDEs are implicated in such alteration and they could represent promising targets for therapeutic intervention.

Ion channels as effectors of cyclic nucleotide pathways: Functional relevance for arterial tone regulation

Numerous mediators and drugs regulate blood flow or arterial pressure by acting on vascular tone, involving cyclic nucleotide intracellular pathways. These signals lead to regulation of several cellular effectors, including ion channels that tune cell membrane potential, Ca²⁺ influx and vascular tone. The characterization of these vasocontrictive or vasodilating mechanisms has grown in complexity due to i) the variety of ion channels that are expressed in both vascular endothelial and smooth muscle cells, ii) the heterogeneity of responses among the various vascular beds, and iii) the number of molecular mechanisms involved in cyclic nucleotide signalling in health and disease. This review synthesizes key data from literature that highlight ion channels as physiologically relevant effectors of cyclic nucleotide pathways in the vasculature, including the characterization of the molecular mechanisms involved. In smooth muscle cells, cation influx or chloride efflux through ion channels are associated with vasoconstriction, whereas K⁺ efflux repolarizes the cell membrane potential and mediates vasodilatation. Both categories of ion currents are under the influence of cAMP and cGMP pathways. Evidence that some ion channels are influenced by CN signalling in endothelial cells will also be presented. Emphasis will also be put on recent data touching a variety of determinants such as phosphodiesterases, EPAC and kinase anchoring, that complicate or even challenge former paradigms.

Denatonium enhanced the tone of denuded rat aorta via bitter taste receptor and phosphodiesterase activation

Bitter taste receptors (Tas2rs) initiate a bitter taste signaling involving the activation of taste-specific G protein gustducin and phosphodiesterases (PDEs); it leads to the decrease of cytosolic level of cyclic adenosine monophosphate (cAMP) in taste cells. Recent studies have identified the expression of Tas2rs in a variety of non-lingual tissues including vascular smooth muscle (VSM), pulmonary smooth muscle and airway smooth muscle. The current study aims to determine the expression of Tas2rs and gustducin in rat aortic smooth muscle tissue and to investigate the effect of Tas2rs agonist denatonium on the tone of isolated denuded aorta rings. Here we reported the expression of six subtypes of Tas2r mRNA and the taste receptor-associated G proteins in endothelium-denuded aorta. Immunostaining experiments showed that the protein of gustducin expressed in vascular smooth muscle cells (VSMCs). Furthermore, denatonium increased the tone of freshly isolated denuded aorta rings in a concentration-dependent manner, and the potentiation effect of denatonium was blocked by a Tas2rs antagonist adenosine 5'-monophosphate (5'-AMP), by the cAMP-hydrolyzing PDE inhibitors, and by a cAMP-synthesizing enzyme activator forskolin, respectively. The blockade of G_βγ signaling did not have a negative impact on the denatonium-induced tonic contractions. These findings suggested that the functional Tas2rs and gustducin are expressed in rat aortic smooth muscle and that denatonium might increase the smooth muscle tone through a Tas2rs signaling pathway involving the activation of PDEs.

Acute Enhancement of Cardiac Function by Phosphodiesterase Type 1 Inhibition

BACKGROUND

Phosphodiesterase type-1 (PDE1) hydrolyzes cAMP and cGMP and is constitutively expressed in the heart, although cardiac effects from its acute inhibition in vivo are largely unknown. Existing data are limited to rodents expressing mostly the cGMP-favoring PDE1A isoform. Human heart predominantly expresses PDE1C with balanced selectivity for cAMP and cGMP. Here, we determined the acute effects of PDE1 inhibition in PDE1C-expressing mammals, dogs, and rabbits, in normal and failing hearts, and explored its regulatory pathways.

METHODS

Conscious dogs chronically instrumented for pressure-volume relations were studied before and after tachypacing-induced heart failure (HF). A selective PDE1 inhibitor (ITI-214) was administered orally or intravenously±dobutamine. Pressure-volume analysis in anesthetized rabbits tested the role of β-adrenergic and adenosine receptor signaling on ITI-214 effects. Sarcomere and calcium dynamics were studied in rabbit left ventricular myocytes.

RESULTS

In normal and HF dogs, ITI-214 increased load-independent contractility, improved relaxation, and reduced systemic arterial resistance, raising cardiac output without altering systolic blood pressure. Heart rate increased, but less so in HF dogs. ITI-214 effects were additive to β-adrenergic receptor agonism (dobutamine). Dobutamine but not ITI-214 increased plasma cAMP. ITI-214 induced similar cardiovascular effects in rabbits, whereas mice displayed only mild vasodilation and no contractility effects. In rabbits, β-adrenergic receptor blockade (esmolol) prevented ITI-214-mediated chronotropy, but inotropy and vasodilation remained unchanged. By contrast, adenosine A_2B-receptor blockade (MRS-1754) suppressed ITI-214 cardiovascular effects. Adding fixed-rate atrial pacing did not alter the findings. ITI-214 alone did not affect sarcomere or whole-cell calcium dynamics, whereas β-adrenergic receptor agonism (isoproterenol) or PDE3 inhibition (cilostamide) increased both. Unlike cilostamide, which further enhanced shortening and peak calcium when combined with isoproterenol, ITI-214 had no impact on these responses. Both PDE1 and PDE3 inhibitors increased shortening and accelerated calcium decay when combined with forskolin, yet only cilostamide increased calcium transients.

CONCLUSIONS

PDE1 inhibition by ITI-214 in vivo confers acute inotropic, lusitropic, and arterial vasodilatory effects in PDE1C-expressing mammals with and without HF. The effects appear related to cAMP signaling that is different from that provided via β-adrenergic receptors or PDE3 modulation. ITI-214, which has completed phase I trials, may provide a novel therapy for HF.

Combination phosphodiesterase type 4 inhibitor and phosphodiesterase type 5 inhibitor treatment reduces non-voiding contraction in a rat model of overactive bladder

Introduction

Current treatments for overactive bladder (OAB) are often discontinued due to side effects or lack of efficacy. The goal of this study was to determine if combining a phosphodiesterase type 4 inhibitor (PDE4i); with a type 5 inhibitor (PDE5i); would have a beneficial effect on OAB symptoms and if a reduced dose of PDE4i in combination with PDE5i could also provide a beneficial effect in OAB. We hypothesized that PDE5i and PDE4i combination treatment could be utilized to reduce non-voiding contractions and smooth muscle disruption in a rat model of OAB.

Methods

Fifty-eight age-matched Sprague-Dawley rats underwent PBOO and daily gavage with PDE4i alone (roflumilast; 1mg/kg), PDE5i alone (tadalafil;10mg/kg), high dose combination (PDE4i 1mg/kg, PDE5i 10mg/kg), low dose combination (PDE4i 0.2mg/kg, PDE5i 10mg/kg), or vehicle for 28 days. Fourteen animals underwent sham PBOO with vehicle. Rats underwent conscious and anesthetized cystometry 28 days after PBOO and were euthanized for qualitative bladder histology. One-way ANOVA on ranks with a Dunn’s post hoc test was used to indicate statistically significant differences between groups (p<0.05).

Results

Bladder & urethral weight was significantly increased after PBOO with vehicle, PDE4i alone, and PDE5i alone, but not with either combination treatment. Frequency of non-voiding contractions during both conscious and anesthetized cystometry increased significantly after PBOO with vehicle, but not after PDE4i or high dose combination treatments compared to sham PBOO. Threshold pressure for voiding was significantly decreased with high dose combination compared to vehicle. PBOO treated with PDE4i alone or high dose combination showed less bladder smooth muscle fibrosis than vehicle, PDE5i alone, or low dose combination treatments.

Conclusion

A PDE4i and PDE5i combination treatment has potential benefit in reducing OAB symptoms, but future research is needed.

Tyrosine kinase inhibitors relax pulmonary arteries in human and murine precision-cut lung slices

BACKGROUND

Tyrosine kinase inhibitors (TKIs) inhibit the platelet derived growth factor receptor (PDGFR) and gain increasing significance in the therapy of proliferative diseases, e.g. pulmonary arterial hypertension (PAH). Moreover, TKIs relax pulmonary vessels of rats and guinea pigs. So far, it is unknown, whether TKIs exert relaxation in human and murine pulmonary vessels. Thus, we studied the effects of TKIs and the PDGFR-agonist PDGF-BB in precision-cut lung slices (PCLS) from both species.

METHODS

The vascular effects of imatinib (mice/human) or nilotinib (human) were studied in Endothelin-1 (ET-1) pre-constricted pulmonary arteries (PAs) or veins (PVs) by videomicroscopy. Baseline initial vessel area (IVA) was defined as 100%. With regard to TKI-induced relaxation, K⁺-channel activation was studied in human PAs (PCLS) and imatinib/nilotinib-related changes of cAMP and cGMP were analysed in human PAs/PVs (ELISA). Finally, the contractile potency of PDGF-BB was explored in PCLS (mice/human).

RESULTS

Murine PCLS: Imatinib (10 μM) relaxed ET-1-pre-constricted PAs to 167% of IVA. Vice versa, 100 nM PDGF-BB contracted PAs to 60% of IVA and pre-treatment with imatinib or amlodipine prevented PDGF-BB-induced contraction. Murine PVs reacted only slightly to imatinib or PDGF-BB. Human PCLS: 100 μM imatinib or nilotinib relaxed ET-1-pre-constricted PAs to 166% or 145% of IVA, respectively, due to the activation of K_ATP-, BK_Ca²⁺- or K_v-channels. In PVs, imatinib exerted only slight relaxation and nilotinib had no effect. Imatinib and nilotinib increased cAMP in human PAs, but not in PVs. In addition, PDGF-BB contracted human PAs/PVs, which was prevented by imatinib.

CONCLUSIONS

TKIs relax pre-constricted PAs/PVs from both, mice and humans. In human PAs, the activation of K⁺-channels and the generation of cAMP are relevant for TKI-induced relaxation. Vice versa, PDGF-BB contracts PAs/PVs (human/mice) due to PDGFR. In murine PAs, PDGF-BB-induced contraction depends on intracellular calcium. So, PDGFR regulates the tone of PAs/PVs. Since TKIs combine relaxant and antiproliferative effects, they may be promising in therapy of PAH.

Improvement of pulmonary arterial hypertension, inflammatory response, and epithelium injury by dual activation of cAMP/cGMP pathway in a rat model of monocrotaline-induced pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening lung disease. PH with concomitant lung diseases, e.g., idiopathic pulmonary fibrosis, is associated with poor prognosis. Development of novel therapeutic vasodilators for treatment of these patients is a key imperative. We evaluated the efficacy of dual activation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) using an active, small-molecule phosphodiesterase (PDE4)/PDE5 dual inhibitor (Compound A). Compound A increased both cAMP and cGMP levels in WI-38 lung fibroblasts and suppressed the expressions of type-1 collagen α1 chain and fibronectin. Additionally, compound A reduced right ventricular weight/left ventricular weight+septal weight ratio, brain natriuretic peptide expression levels in right ventricle, C─C motif chemokine ligand 2 expression levels in lung, and plasma surfactant protein D. Our data indicate that dual activation of cAMP/cGMP pathways may be a novel treatment strategy for PH.

Mirabegron induces relaxant effects via cAMP signaling-dependent and -independent pathways in detrusor smooth muscle

OBJECTIVE

We previously found that mirabegron exerts a relaxant effect in the presence of the β₃ -adrenoceptor antagonist SR58894A during carbachol-induced contraction in human and pig detrusor. The aim of this study was to explore the possible mechanism underlying the relaxant effects of mirabegron using detrusor smooth muscle.

METHODS

Human tissue was obtained from urinary bladders of patients undergoing radical cystectomy at Kyushu University and Harasanshin Hospital. Pig tissue was obtained from an abattoir. Tension force (organ bath experiments) was measured in intact or permeabilised (α-toxin or β-escin) detrusor smooth muscle strips. The contribution of cAMP-dependent signaling and the inhibition of Ca²⁺ sensitization to the relaxant effects of mirabegron were characterized using 1 μM SR58894A, 100 μM SQ22536 (an adenylyl cyclase inhibitor), 10 μM H-89 (a protein kinase [PK] A inhibitor), 10 μM Y-27632 (a selective Rho kinase inhibitor), and 10 μM GF-109203X (a selective PKC inhibitor).

RESULTS

30 μM Mirabegron impaired carbachol (0.03-1 μM)-induced contraction in human detrusor smooth muscle. SR58894A only partially attenuated the relaxant effects of mirabegron in human and pig detrusor strips precontracted with 1 μM carbachol. In α-toxin-permeabilized detrusor strips, tension force at 1 μM [Ca²⁺ ]_i was decreased by mirabegron in a concentration-dependent manner. The relaxant effect of mirabegron was only slightly attenuated by H-89 and not significantly affected by SQ22536. Y-27632 potentiated the relaxation response to mirabegron, but attenuated responses to cAMP; GF-109203X had little effect. Mirabegron but not cAMP had a notable relaxant effect in the pig detrusor smooth muscle permeabilized with β-escin.

CONCLUSIONS

Mirabegron-induced relaxation of pig and human detrusor smooth muscle occurs via both a β₃ -adrenoceptor/cAMP-dependent and -independent pathway.

Progesterone and cAMP synergize to inhibit responsiveness of myometrial cells to pro-inflammatory/pro-labor stimuli

Progesterone (P4) acting through the P4 receptor (PR) isoforms, PR-A and PR-B, promotes uterine quiescence for most of pregnancy, in part, by inhibiting the response of myometrial cells to pro-labor inflammatory stimuli. This anti-inflammatory effect is inhibited by phosphorylation of PR-A at serine-344 and -345 (pSer^344/345-PRA). Activation of the cyclic adenosine monophosphate (cAMP) signaling pathway also promotes uterine quiescence and myometrial relaxation. This study examined the cross-talk between P4/PR and cAMP signaling to exert anti-inflammatory actions and control pSer^344/345-PRA generation in myometrial cells. In the hTERT-HM^A/B immortalized human myometrial cell line P4 inhibited responsiveness to interleukin (IL)-1β and forskolin (increases cAMP) and 8-Br-cAMP increased this effect in a concentration-dependent and synergistic manner that was mediated by activation of protein kinase A (PKA). Forskolin also inhibited the generation of pSer^344/345-PRA and expression of key contraction-associated genes. Generation of pSer^344/345-PRA was catalyzed by stress-activated protein kinase/c-Jun NH₂-terminal kinase (SAPK/JNK). Forskolin inhibited pSer^344/345-PRA generation, in part, by increasing the expression of dual specificity protein phosphatase 1 (DUSP1), a phosphatase that inactivates mitogen-activated protein kinases (MAPKs) including SAPK/JNK. P4/PR and forskolin increased DUSP1 expression. The data suggest that P4/PR promotes uterine quiescence via cross-talk and synergy with cAMP/PKA signaling in myometrial cells that involves DUSP1-mediated inhibition of SAPK/JNK activation.

Decreased PKG transcription mediated by PI3K/Akt/FoxO1 pathway is involved in the development of nitroglycerin tolerance

Phosphoinositide 3-kinase (PI3K)/Akt plays a pivotal role in the vascular response. The present study is to determine whether PI3K/Akt pathway in vascular smooth muscle cells is involved in nitroglycerin (NTG) tolerance and the underlying mechanism. Nitrate tolerance of porcine coronary arteries in vitro was induced by incubation of NTG (10^-5 M) for 24 h. Nitrate tolerance in vivo was obtained by subcutaneous injection of mice with NTG (20 mg kg^-1, tid, 3 days) and the aortas were used. Protein levels of total and phosphorylated Akt, forkhead box protein O1 (FoxO1), and cGMP-dependent protein kinase (PKG) were determined by western blot analysis. Isometric vessel tension was recorded by organ chamber technique. PKG mRNA was determined by real-time PCR. The cellular translocation of FoxO1 was observed by immunofluorescence. Reactive oxygen species (ROS) level was measured by DHE staining. The vascular relaxation to NTG was significantly inhibited in in vivo and in vitro NTG tolerant arteries. Meanwhile, the protein level of phosphorylated Akt at Ser473 was increased in the tolerant arteries. The attenuated relaxation and the augmented Akt-p were ameliorated by LY294002, a specific inhibitor of PI3K. The protein and mRNA expression of PKG were significantly down-regulated in NTG tolerant arteries, which were reversed by LY294002. The level of phosphorylated FoxO1 at Ser256 and its translocation from the nucleus to the cytosol were both increased in NTG tolerance and were also inhibited by LY294002. ROS production was significantly increased in NTG tolerant arteries, which was not be affected by LY294002 but inhibited by N-acetyl-L-cysteine. In conclusion, the present study suggests that PI3K/Akt in vascular smooth muscle is involved in the development of NTG tolerance via inhibiting PKG transcription and the effect is mediated by FoxO1.

Kv7 potassium channels as signal transduction intermediates in the control of microvascular tone

Potassium channels are recognized as important regulators of cellular functions in most, if not all cell types. These cellular proteins assemble to form gated pores in the plasma membrane, which serve to regulate the flow of potassium ions (K⁺ ) from the cytosol to the extracellular space. In VSMCs, the open state of potassium channels enables the efflux of K⁺ and thereby establishes a negative resting voltage across the plasma membrane that inhibits the opening of VSCCs. Under these conditions, cytosolic Ca²⁺ concentrations are relatively low and Ca²⁺ -dependent contraction is inhibited. Recent research has identified Kv7 family potassium channels as important contributors to resting membrane voltage in VSMCs, with much of the research focusing on the effects of drugs that specifically activate or block these channels to produce corresponding effects on VSMC contraction and vascular tone. Increasingly, evidence is emerging that these channels are not just good drug targets-they are also essential intermediates in vascular signal transduction, mediating vasoconstrictor or vasodilator responses to a variety of physiological stimuli. This review will summarize recent research findings that support a crucial function of Kv7 channels in both positive (vasoconstrictive) and negative (vasorelaxant) regulation of microvascular tone.

Eulophia macrobulbon extract relaxes rat isolated pulmonary artery and protects against monocrotaline-induced pulmonary arterial hypertension

BACKGROUND

Extract of the wild orchid, Eulophia macrobulbon (EM) inhibits phosphodiesterase5 (PDE5) suggesting it could preferentially dilate the pulmonary vasculature.

PURPOSE AND STUDY DESIGN

To pharmacologically characterize the vascular actions of EM ethanolic extract and its active compound, 1-(4'-hydroxybenzyl)-4,8-dimethoxyphenanthrene-2,7-diol using isolated pulmonary arteries (PA) from rats having pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). PA were fixed and prepared for histology.

RESULTS

EM extract relaxed PA (EC₅₀ = 0.17  mg/ml, E_max ∼ 94%) but less so for aorta (EC₅₀ = 0.51 mg/ml, E_max ∼ 62%), suggesting some selectivity towards the pulmonary circulation. PA vasorelaxation was reduced by endothelial removal or N^G-nitro-L-arginine methyl ester, but unaffected by indomethacin, apamin +charybdotoxin, 4-aminopyridine, glibenclamide, iberiotoxin, or 1H - [1,2,4]oxadiazolo[4,3-a]quinoxalin -1- one. Sodium nitroprusside-induced relaxation was enhanced by EM extract, probably via PDE5 inhibition. EM extract reduced contractions evoked by extracellular Ca²⁺application, and inhibited intracellular Ca²⁺release activated by phenylephrine. The phenanthrene relaxed PA independently of the endothelium. MCT thickened walls and decreased lumens of PA, and hypertrophied right ventricular myocytes, effects ameliorated by 3 weeks of oral sildenafil (20  mg/kg) or EM extract (15, 450 or 1000  mg/kg).

CONCLUSION

PAH is improved by EM extract acting through PA relaxation mediated through endothelial NO, reduced Ca²⁺-mobilization, and reduced PA wall thickness and right ventricular hypertrophy.

Progesterone induces relaxation of human umbilical cord vascular smooth muscle cells through mPRα (PAQR7)

Progesterone effects on vascular smooth muscle cell (VSMC) relaxation and the mechanism were investigated in cultured human umbilical vein VSMCs. Membrane progesterone receptors mPRα, mPRβ, and mPRγ were highly expressed in VSMCs, whereas nuclear progesterone receptor (nPR) had low expression. Progesterone (20 nM) and 02-0 (mPR-selective agonist), but not R5020 (nPR agonist), induced muscle relaxation in both a VSMC collagen gel disk contraction assay and an endothelium-denuded human umbilical artery ring tension assay. Progesterone and 02-0 increased ERK and Akt phosphorylation and decreased cAMP levels. These effects were blocked by preincubation with pertussis toxin. Progestin-induced muscle relaxation was blocked by pretreatment with mPRα, but not nPR, siRNAs, and by co-treatment with 8-Br-cAMP, AZD6244 (MAP kinase inhibitor), and wortmannin (PI3K inhibitor). Progestins reduced myosin light chain phosphorylation which was blocked with AZD6244 and wortmannin. These results demonstrate progesterone directly relaxes human VSMCs through mPRα/Gi and MAP kinase/ERK-, Akt/PI3K-, and cAMP-dependent pathways.

Endothelial cell α-globin and its molecular chaperone α-hemoglobin-stabilizing protein regulate arteriolar contractility

Arteriolar endothelial cell-expressed (EC-expressed) α-globin binds endothelial NOS (eNOS) and degrades its enzymatic product, NO, via dioxygenation, thereby lessening the vasodilatory effects of NO on nearby vascular smooth muscle. Although this reaction potentially affects vascular physiology, the mechanisms that regulate α-globin expression and dioxygenase activity in ECs are unknown. Without β-globin, α-globin is unstable and cytotoxic, particularly in its oxidized form, which is generated by dioxygenation and recycled via endogenous reductases. We show that the molecular chaperone α-hemoglobin-stabilizing protein (AHSP) promotes arteriolar α-globin expression in vivo and facilitates its reduction by eNOS. In Ahsp-/- mice, EC α-globin was decreased by 70%. Ahsp-/- and Hba1-/- mice exhibited similar evidence of increased vascular NO signaling, including arteriolar dilation, blunted α1-adrenergic vasoconstriction, and reduced blood pressure. Purified α-globin bound eNOS or AHSP, but not both together. In ECs in culture, eNOS or AHSP enhanced α-globin expression posttranscriptionally. However, only AHSP prevented oxidized α-globin precipitation in solution. Finally, eNOS reduced AHSP-bound α-globin approximately 6-fold faster than did the major erythrocyte hemoglobin reductases (cytochrome B5 reductase plus cytochrome B5). Our data support a model whereby redox-sensitive shuttling of EC α-globin between AHSP and eNOS regulates EC NO degradation and vascular tone.

The clinical effects of l-arginine and asymmetric dimethylarginine: implications for treatment in secondary Raynaud's phenomenon

Secondary Raynaud's phenomenon (RP) is often the sentinel clinical finding in systemic sclerosis and may precede systemic disease by several years. Altered nitric oxide metabolism plays a critical role in both fibrosis and severe secondary RP phenotypes in these patients. Increased flux through inducible nitric oxide synthase (iNOS) drives cutaneous fibrosis. Failure of flux through endothelial nitric oxide synthase (eNOS) contributes to increased vasoconstriction and decreased vasorelaxation. The underproduction of nitric oxide by eNOS is in part due to increased levels of asymmetric dimethylarginine (ADMA), an endogenous competitive inhibitor of nitric oxide synthase. The inhibitory effects of increased ADMA levels may be counteracted increasing serum l‐arginine, which is often an effective treatment strategy in these patients. As such, l‐arginine‐based therapies should be considered in managing secondary RP, particularly given their favourable safety and tolerability profile. While there is no established dosing regimen, studies of oral l‐arginine in secondary RP suggest that divided dosing may begin at 1–2 g/day and may be titrated up to 10 g/day. Conversely, primary RP is not associated with increased ADMA production which likely accounts for the failure of l‐arginine trials to show benefit in primary RP.