Response Of Smooth Muscle Research Articles

Coronary microvascular dysfunction in postmenopausal minipigs with multiple risk factors

Abstract Background Coronary microvascular angina occurs in both men and women, however, the majority of patients are postmenopausal women with multiple cardiovascular risk factors, such as diabetes mellitus (DM), chronic kidney disease (CKD) and dyslipidemia. No treatment is available for coronary microvascular dysfunction, requiring more in depth knowledge on the mechanisms underlying this syndrome in this expanding group of patients. Purpose Here we studied microvascular function in vivo and and in vitro in isolated small coronary arteries, in post-menopausal miniswine with multiple cardiovascular risk factors. Methods DM (streptozotocin), hypercholesterolemia (HC, high fat, high sugar diet), CKD (renal artery embolization) and menopause (ovariectomy, OVX) were induced in 5 adult female minipigs (1.5-2 years old, ~40kg, DM+HC+CKD+OVX) for 6 months, while 11 healthy age- and weight-matched female minipigs on normal pig chow served as controls (Normal). At sacrifice, coronary flow reserve (CFR) in response to intracoronary infusion of adenosine was measured under anesthesia. Isolated small coronary arteries were used to study the endothelium-dependent response to bradykinin in the presence and absence of eNOS blockade with LNAME, and cyclooxygenase inhibition by indomethacin, and endothelium-independent response to the nitric oxide (NO) donor, SNAP. Results 6 months of sustained hyperglycemia (17.5±1.0 in DM+HC+CKD+OVX vs 8.2±0.9 mmol/l in Normal, P<0.05 by t-test), hypercholesterolemia (15.4±2.0 vs 1.7±0.1 mmol/l, P<0.05), renal dysfunction (NGAL: 205±72 vs 67±5 ng/ml, P<0.05) and low progesterone levels (13.1±5.7 in DM+HC+CKD+OVX vs 92.0±30.0 nmol/l in Normal, P=0.1) were accompanied by systemic inflammation (TNFα: 62±7 vs 47±1 pg/ml, P<0.05). CFR was significantly reduced in DM+HC+CKD+OVX as compared to the healthy animals (panel A). Coronary small arteries from DM+HC+CKD+OVX animals showed impaired endothelium-dependent vasodilation to bradykinin (panel B), which was mediated by a loss of NO (panels C & D). The loss of NO was partly compensated for by activation of the cyclooxygenase pathway, as indomethacin blunted the dilation to bradykinin in the DM+HC+CKD+OVX animals, but had no effect on the dilation to bradykinin in Normals (panels C & D). Endothelium-independent dilation to SNAP was also impaired in DM+HC+CKD+OVX animals, indicating blunted vascular smooth muscle responsiveness to nitric oxide (panel E). Conclusion Postmenopausal minipigs with multiple risk factors, displayed severe coronary microvascular dysfunction as evidenced by a significantly reduced coronary flow reserve and both reduced NO sensitivity/ production, indicating endothelial and smooth muscle cell dysfunction. Loss of NO-mediated vasodilation was partially compensated by activation of cyclooxygenase pathway. Such perturbations may contribute to reduced myocardial perfusion that is often observed in post-menopausal women with multiple cardiovascular risk factors.

Spasmolytic Activity of 1,3-Disubstituted 3,4-Dihydroisoquinolines.

This article concerns the spasmolytic activities of some novel 1,3-disubstituted 3,4-dihydroisoquinolines. These compounds can be evaluated as potential therapeutic candidates according to Lipinski's rule of five, showing high gastrointestinal absorption and the ability to cross the blood-brain barrier, which is a very important parameter in the drug discovery processes. In silico simulation predicted smooth muscle relaxant activity for all the compounds. Since smooth muscle contractile failure is a characteristic feature of many disorders, in the current paper, we concentrate on the parameters of the spontaneous contractile responses of smooth muscle (SM) cells compared to the well-known drug mebeverine. Two of the newly synthesized substances can be identified as essential modulating regulators and potentially used as therapeutic molecules. One of these molecules also showed significant DPPH antioxidant activity compared to rutin.

Role of NaV1.7 in postganglionic sympathetic nerve function in human and guinea-pig arteries.

NaV1.7 plays a crucial role in inducing and conducting action potentials in pain-transducing sensory nociceptor fibres, suggesting that NaV1.7 blockers could be effective non-opioid analgesics. While SCN9A is expressed in both sensory and autonomic neurons, its functional role in the autonomic system remains less established. Our single neuron rt-PCR analysis revealed that 82% of sympathetic neurons isolated from guinea-pig stellate ganglia expressed NaV1.7 mRNA, with NaV1.3 being the only other tetrodotoxin-sensitive channel expressed in approximately 50% of neurons. We investigated the role of NaV1.7 in conducting action potentials in postganglionic sympathetic nerves and in the sympathetic adrenergic contractions of blood vessels using selective NaV1.7 inhibitors. Two highly selective NaV1.7 blockers, GNE8493 and PF05089771, significantly inhibited postganglionic compound action potentials by approximately 70% (P<0.01), with residual activity being blocked by the NaV1.3 inhibitor, ICA121431. Electrical field stimulation (EFS) induced rapid contractions in guinea-pig isolated aorta, pulmonary arteries, and human isolated pulmonary arteries via stimulation of intrinsic nerves, which were inhibited by prazosin or the NaV1 blocker tetrodotoxin. Our results demonstrated that blocking NaV1.7 with GNE8493, PF05089771, or ST2262 abolished or strongly inhibited sympathetic adrenergic responses in guinea-pigs and human vascular smooth muscle. These findings support the hypothesis that pharmacologically inhibiting NaV1.7 could potentially reduce sympathetic and parasympathetic function in specific vascular beds and airways. KEY POINTS: 82% of sympathetic neurons isolated from the stellate ganglion predominantly express NaV1.7 mRNA. NaV1.7 blockers inhibit action potential conduction in postganglionic sympathetic nerves. NaV1.7 blockade substantially inhibits sympathetic nerve-mediated adrenergic contractions in human and guinea-pig blood vessels. Pharmacologically blocking NaV1.7 profoundly affects sympathetic and parasympathetic responses in addition to sensory fibres, prompting exploration into the broader physiological consequences of NaV1.7 mutations on autonomic nerve activity.

Imaging the dynamics of murine uterine contractions in early pregnancy†.

Uterine muscle contractility is essential for reproductive processes including sperm and embryo transport, and during the uterine cycle to remove menstrual effluent. Even still, uterine contractions have primarily been studied in the context of preterm labor. This is partly due to a lack of methods for studying the uterine muscle contractility in the intact organ. Here, we describe an imaging-based method to evaluate mouse uterine contractility of both the longitudinal and circular muscles in the cycling stages and in early pregnancy. By transforming the image-based data into three-dimensional spatiotemporal contractility maps, we calculate waveform characteristics of muscle contractions, including amplitude, frequency, wavelength, and velocity. We report that the native organ is highly contractile during the progesterone-dominant diestrus stage of the cycle when compared to the estrogen-dominant proestrus and estrus stages. We also observed that during the first phase of uterine embryo movement when clustered embryos move toward the middle of the uterine horn, contractions are dynamic and non-uniform between different segments of the uterine horn. In the second phase of embryo movement, contractions are more uniform and rhythmic throughout the uterine horn. Finally, in Lpar3-/- uteri, which display faster embryo movement, we observe global and regional increases in contractility. Our method provides a means to understand the wave characteristics of uterine smooth muscle in response to modulators and in genetic mutants. Better understanding uterine contractility in the early pregnancy stages is critical for the advancement of artificial reproductive technologies and a possibility of modulating embryo movement during clinical embryo transfers.

Empagliflozin, an SGLT2i, relaxes coronary smooth muscle at pharmacological concentrations

Morbidity and mortality due to heart failure with preserved ejection fraction (HFpEF) is increasing and there are no universally recognized strategies for treatment. Sodium-glucose co-transporter type 2 inhibitors (SGLT2i), such as Empagliflozin, have been shown to reduce myocardial stiffness and improve coronary microvascular performance, but mechanisms are unclear. Previous studies in rabbit aorta and rat mesentery suggest Empagliflozin relaxes smooth muscle through activation of K+ channels. This study investigated the effects of therapeutic and pharmacological concentrations of Empagliflozin (10-300 μM) on the isometric tension of left circumflex (CFX) coronary arteries from Yorkshire swine. We tested the hypothesis that Empagliflozin would relax coronary smooth muscle via a concentration-dependent manner, involving K+ channels. CFX arteries were dissected, cleaned of adventitia, cut into 3 mm rings (n = 16), and mounted in organ baths containing Krebs-Henseleit buffer (37 °C) for isometric tension studies. Each CFX segment was adjusted to optimal preload (~3 g passive tension) as determined by &lt;10 % change in active tension in response to 60 mM KCl. In order to determine whether Empagliflozin caused relaxation and, if so, by what mechanism, rings were contracted with either 30 mM K+ or the thromboxane mimetic U46619 (1 μM). Once tension plateaued, Empagliflozin (10-300 μM) was added in increasing concentrations. Therapeutic concentrations of Empagliflozin (10-30 μM), elicited no significant relaxation. Pharmacologic concentrations of Empagliflozin (≥100 μM) caused significant relaxation from ~15 ± 11% to ~45 ± 10% in response to 100 μM vs. 300 μM Empagliflozin, respectively. Relaxation was not different between rings contracted with K+ or U46619, suggesting membrane hyperpolarization via K+ channels is not involved. Our results represent the first study of the effects of Empagliflozin on coronary smooth muscle reactivity. Data support the idea that relaxation of coronary smooth muscle by Empagliflozin occurs at supra-pharmacologic concentrations in vitro, but K+ channel activation appears to be an unlikely mechanism. This project was supported by National Institutes of Health grant R01 HL158723. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Remodeling of Murine Branch Pulmonary Arteries Under Chronic Hypoxia and Short-Term Normoxic Recovery.

Chronic hypoxia plays a central role in diverse pulmonary pathologies, but its effects on longitudinal changes in the biomechanical behavior of proximal pulmonary arteries remain poorly understood. Similarly, effects of normoxic recovery have not been well studied. Here, we report hypoxia-induced changes in composition, vasoactivity, and passive biaxial mechanics in the main branch pulmonary artery of male C57BL/6J mice exposed to 10% FiO2 for 1, 2, or 3 weeks. We observed significant changes in extracellular matrix, and consequently wall mechanics, as early as 1 week of hypoxia. While circumferential stress and stiffness returned toward normal values by 2-3 weeks of hypoxia, area fractions of cytoplasm and thin collagen fibers did not return toward normal until after 1 week of normoxic recovery. By contrast, elastic energy storage and overall distensibility remained reduced after 3 weeks of hypoxia as well as following 1 week of normoxic recovery. While smooth muscle and endothelial cell responses were attenuated under hypoxia, smooth muscle but not endothelial cell responses recovered following 1 week of subsequent normoxia. Collectively, these data suggest that homeostatic processes were unable to preserve or restore overall function, at least over a brief period of normoxic recovery. Longitudinal changes are critical in understanding large pulmonary artery remodeling under hypoxia, and its reversal, and will inform predictive models of vascular adaptation.

Rosmarinic acid improves tracheal smooth muscle responsiveness and lung pathological changes in ovalbumin-sensitized rats

Objective: To evaluate the effect of rosmarinic acid on tracheal smooth muscle responsiveness and lung pathological changes in ovalbumin-sensitized rats. Methods: Rats were randomly divided into six groups: the control group, the asthmatic group, and the asthmatic groups treated with dexamethasone (1 mg/kg; oral gavage) or three doses of rosmarinic acid (0.5, 1, and 2 mg/kg; oral gavage). For induction of asthma, rats received intraperitoneal injections and inhalation of ovalbumin. After 21 days, bronchoalveolar lavage fluid and lung samples were collected for histopathological analyses. Moreover, total and differential white blood cell counts were determined. Results: The rosmarinic acid-treated group had significantly lower tracheal smooth muscle responses to methacholine than the asthmatic group. In addition, rosmarinic acid reduced white blood cell count and the percentages of eosinophils, monocytes, and neutrophils while increasing the percentage of lymphocytes. Ovalbumin-induced lung pathological changes were significantly improved by treatment with rosmarinic acid. Conclusions: Rosmarinic acid improves tracheal smooth muscle responsiveness and lung pathological changes in ovalbumin-sensitized rats.

ATP-Induced Contractile Response of Esophageal Smooth Muscle in Mice.

The tunica muscularis of mammalian esophagi is composed of striated muscle and smooth muscle. Contraction of the esophageal striated muscle portion is mainly controlled by cholinergic neurons. On the other hand, smooth muscle contraction and relaxation are controlled not only by cholinergic components but also by non-cholinergic components in the esophagus. Adenosine triphosphate (ATP) is known to regulate smooth muscle contraction and relaxation in the gastrointestinal tract via purinergic receptors. However, the precise mechanism of purinergic regulation in the esophagus is still unclear. Therefore, the aim of the present study was to clarify the effects of ATP on the mechanical responses of the esophageal muscle in mice. An isolated segment of the mouse esophagus was placed in a Magnus's tube and longitudinal mechanical responses were recorded. Exogenous application of ATP induced contractile responses in the esophageal preparations. Tetrodotoxin, a blocker of voltage-dependent sodium channels in neurons and striated muscle, did not affect the ATP-induced contraction. The ATP-evoked contraction was blocked by pretreatment with suramin, a purinergic receptor antagonist. RT-PCR revealed the expression of mRNA of purinergic receptor genes in the mouse esophageal tissue. The findings suggest that purinergic signaling might regulate the motor activity of mouse esophageal smooth muscle.

The conducted vascular response as a mediator of hypercapnic cerebrovascular reactivity: A modelling study

It is well established that the cerebral blood flow (CBF) shows exquisite sensitivity to changes in the arterial blood partial pressure of CO2 (Pa,CO2), which is reflected by an index termed cerebrovascular reactivity. In response to elevations in Pa,CO2 (hypercapnia), the vessels of the cerebral microvasculature dilate, thereby decreasing the vascular resistance and increasing CBF. Due to the challenges of access, scale and complexity encountered when studying the microvasculature, however, the mechanisms behind cerebrovascular reactivity are not fully understood. Experiments have previously established that the cholinergic release of the Acetylcholine (ACh) neurotransmitter in the cortex is a prerequisite for the hypercapnic response. It is also known that ACh functions as an endothelial-dependent agonist, in which the local administration of ACh elicits local hyperpolarization in the vascular wall; this hyperpolarization signal is then propagated upstream the vascular network through the endothelial layer and is coupled to a vasodilatory response in the vascular smooth muscle (VSM) layer in what is known as the conducted vascular response (CVR). Finally, experimental data indicate that the hypercapnic response is more strongly correlated with the CO2 levels in the tissue than in the arterioles. Accordingly, we hypothesize that the CVR, evoked by increases in local tissue CO2 levels and a subsequent local release of ACh, is responsible for the CBF increase observed in response to elevations in Pa,CO2. By constructing physiologically grounded dynamic models of CBF and control in the cerebral vasculature, ones that integrate the available knowledge and experimental data, we build a new model of the series of signalling events and pathways underpinning the hypercapnic response, and use the model to provide compelling evidence that corroborates the aforementioned hypothesis. If the CVR indeed acts as a mediator of the hypercapnic response, the proposed mechanism would provide an important addition to our understanding of the repertoire of metabolic feedback mechanisms possessed by the brain and would motivate further in-vivo investigation. We also model the interaction of the hypercapnic response with dynamic cerebral autoregulation (dCA), the collection of mechanisms that the brain possesses to maintain near constant CBF despite perturbations in pressure, and show how the dCA mechanisms, which otherwise tend to be overlooked when analysing experimental results of cerebrovascular reactivity, could play a significant role in shaping the CBF response to elevations in Pa,CO2. Such in-silico models can be used in tandem with in-vivo experiments to expand our understanding of cerebrovascular diseases, which continue to be among the leading causes of morbidity and mortality in humans.

Asymmetric Dimethylarginine Enables Depolarizing Spikes and Vasospasm in Mesenteric and Coronary Resistance Arteries.

Increased vasoreactivity due to reduced endothelial NO bioavailability is an underlying feature of cardiovascular disease, including hypertension. In small resistance arteries, declining NO enhances vascular smooth muscle (VSM) reactivity partly by enabling rapid depolarizing Ca2+-based spikes that underlie vasospasm. The endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) is metabolized by DDAH1 (dimethylarginine dimethylaminohydrolase 1) and elevated in cardiovascular disease. We hypothesized ADMA might enable VSM spikes and vasospasm by reducing NO bioavailability, which is opposed by DDAH1 activity and L-arginine. Rat isolated small mesenteric arteries and myogenic rat-isolated intraseptal coronary arteries (RCA) were studied using myography, VSM intracellular recording, Ca2+ imaging, and DDAH1 immunolabeling. Exogenous ADMA was used to inhibit NO synthase and a selective DDAH1 inhibitor, NG-(2-methoxyethyl) arginine, to assess the functional impact of ADMA metabolism. ADMA enhanced rat-isolated small mesenteric arteries vasoreactivity to the α1-adrenoceptor agonist, phenylephrine by enabling T-type voltage-gated calcium channel-dependent depolarizing spikes. However, some endothelium-dependent NO-vasorelaxation remained, which was sensitive to DDAH1-inhibition with NG-(2-methoxyethyl) arginine. In myogenically active RCA, ADMA alone stimulated depolarizing Ca2+ spikes and marked vasoconstriction, while NO vasorelaxation was abolished. DDAH1 expression was greater in rat-isolated small mesenteric arteries endothelium compared with RCA, but low in VSM of both arteries. L-arginine prevented depolarizing spikes and protected NO-vasorelaxation in rat-isolated small mesenteric artery and RCA. ADMA increases VSM electrical excitability enhancing vasoreactivity. Endothelial DDAH1 reduces this effect, and low levels of DDAH1 in RCAs may render them susceptible to endothelial dysfunction contributing to vasospasm, changes opposed by L-arginine.

The gut metagenome harbors metabolic and antibiotic resistance signatures of moderate-to-severe asthma.

Asthma is a common allergic airway disease that has been associated with the development of the human microbiome early in life. Both the composition and function of the infant gut microbiota have been linked to asthma risk, but functional alterations in the gut microbiota of older patients with established asthma remain an important knowledge gap. Here, we performed whole metagenomic shotgun sequencing of 95 stool samples from a cross-sectional cohort of 59 healthy and 36 subjects with moderate-to-severe asthma to characterize the metagenomes of gut microbiota in adults and children 6 years and older. Mapping of functional orthologs revealed that asthma contributes to 2.9% of the variation in metagenomic content even when accounting for other important clinical demographics. Differential abundance analysis showed an enrichment of long-chain fatty acid (LCFA) metabolism pathways, which have been previously implicated in airway smooth muscle and immune responses in asthma. We also observed increased richness of antibiotic resistance genes (ARGs) in people with asthma. Several differentially abundant ARGs in the asthma cohort encode resistance to macrolide antibiotics, which are often prescribed to patients with asthma. Lastly, we found that ARG and virulence factor (VF) richness in the microbiome were correlated in both cohorts. ARG and VF pairs co-occurred in both cohorts suggesting that virulence and antibiotic resistance traits are coselected and maintained in the fecal microbiota of people with asthma. Overall, our results show functional alterations via LCFA biosynthetic genes and increases in antibiotic resistance genes in the gut microbiota of subjects with moderate-to-severe asthma and could have implications for asthma management and treatment.

High-fat Western diet alters crystalline silica-induced airway epithelium ion transport but not airway smooth muscle reactivity

ObjectivesSilicosis is an irreversible occupational lung disease resulting from crystalline silica inhalation. Previously, we discovered that Western diet (HFWD)-consumption increases susceptibility to silica-induced pulmonary inflammation and fibrosis. This study investigated the potential of HFWD to alter silica-induced effects on airway epithelial ion transport and smooth muscle reactivity.MethodsSix-week-old male F344 rats were fed a HFWD or standard rat chow (STD) and exposed to silica (Min-U-Sil 5®, 15 mg/m3, 6 h/day, 5 days/week, for 39 d) or filtered air. Experimental endpoints were measured at 0, 4, and 8 weeks post-exposure. Transepithelial potential difference (Vt), short-circuit current (ISC) and transepithelial resistance (Rt) were measured in tracheal segments and ion transport inhibitors [amiloride, Na+ channel blocker; NPPB; Clˉ channel blocker; ouabain, Na+, K+-pump blocker] identified changes in ion transport pathways. Changes in airway smooth muscle reactivity to methacholine (MCh) were investigated in the isolated perfused trachea preparation.ResultsSilica reduced basal ISC at 4 weeks and HFWD reduced the ISC response to amiloride at 0 week compared to air control. HFWD + silica exposure induced changes in ion transport 0 and 4 weeks after treatment compared to silica or HFWD treatments alone. No effects on airway smooth muscle reactivity to MCh were observed.

The 2023 Walter B. Cannon Award Lecture: Mechanisms Regulating Vascular Function and Blood Pressure by the PPARγ-RhoBTB1-CUL3 Pathway.

Human genetic and clinical trial data suggest that peroxisome proliferator activated receptor γ (PPARγ), a nuclear receptor transcription factor plays an important role in the regulation of arterial blood pressure. The examination of a series of novel animal models, coupled with transcriptomic and proteomic analysis, has revealed that PPARγ and its target genes employ diverse pathways to regulate vascular function and blood pressure. In endothelium, PPARγ target genes promote an antioxidant state, stimulating both nitric oxide (NO) synthesis and bioavailability, essential components of endothelial-smooth muscle communication. In vascular smooth muscle, PPARγ induces the expression of a number of genes that promote an antiinflammatory state and tightly control the level of cGMP, thus promoting responsiveness to endothelial-derived NO. One of the PPARγ targets in smooth muscle, Rho related BTB domain containing 1 (RhoBTB1) acts as a substrate adaptor for proteins to be ubiquitinated by the E3 ubiquitin ligase Cullin-3 and targeted for proteasomal degradation. One of these proteins, phosphodiesterase 5 (PDE5) is a target of the Cullin-3/RhoBTB1 pathway. Phosphodiesterase 5 degrades cGMP to GMP and thus regulates the smooth muscle response to NO. Moreover, expression of RhoBTB1 under condition of RhoBTB1 deficiency reverses established arterial stiffness. In conclusion, the coordinated action of PPARγ in endothelium and smooth muscle is needed to maintain NO bioavailability and activity, is an essential regulator of vasodilator/vasoconstrictor balance, and regulates blood vessel structure and stiffness.

β-adrenergic receptor regulates embryonic epithelial extensibility through actomyosin inhibition

During morphogenesis, epithelial tissues reshape and expand to cover the body and organs. The molecular mechanisms of this deformability remain elusive. Here, we investigate the role of the β-adrenergic receptor (ADRB) in orchestrating actomyosin contractility, pivotal for epithelial extensibility. Chemical screens on Xenopus laevis embryos pinpointed ADRB2 as a principal regulator. ADRB2 promotes actomyosin relaxation, facilitating apical cell area expansion during body elongation. In contrast, ADRB2 knockdown results in heightened cell contraction, marked by synchronous oscillation of F-actin and myosin, impeding body elongation. ADRB2 mutants with reduced affinity for ligand binding lack the function to induce cellular relaxation, highlighting the ligand's essential roles even in the developing epidermis. Our findings unveil ADRB2's critical contribution to extensibility of the epidermis and subsequent body elongation during development. This study also offers insights into the physiology of mature epithelial organs deformed by the smooth muscle response to the adrenergic autonomic nervous system.

Circulating Extracellular Vesicles in Subarachnoid Hemorrhage Patients: Characterization and Cellular Effects.

Circulating extracellular vesicles (EVs) may play a pathophysiological role in the onset of complications of subarachnoid hemorrhage (SAH), potentially contributing to the development of vasospasm (VP). In this study, we aimed to characterize circulating EVs in SAH patients and examine their effects on endothelial and smooth muscle cells (SMCs). In a total of 18 SAH patients, 10 with VP (VP), 8 without VP (NVP), and 5 healthy controls (HC), clinical variables were recorded at different time points. EVs isolated from plasma samples were characterized and used to stimulate human vascular endothelial cells (HUVECs) and SMCs. We found that EVs from SAH patients expressed markers of T-lymphocytes and platelets and had a larger size and a higher concentration compared to those from HC. Moreover, EVs from VP patients reduced cell viability and mitochondrial membrane potential in HUVECs and increased oxidants and nitric oxide (NO) release. Furthermore, EVs from SAH patients increased intracellular calcium levels in SMCs. Altogether, our findings reveal an altered pattern of circulating EVs in SAH patients, suggesting their pathogenic role in promoting endothelial damage and enhancing smooth muscle reactivity. These results have significant implications for the use of EVs as potential diagnostic/prognostic markers and therapeutic tools in SAH management.

Quercetin supplementation attenuates airway hyperreactivity and restores airway relaxation in rat pups exposed to hyperoxia.

Hyperoxia exposure of immature lungs contributes to lung injury and airway hyperreactivity. Up to now, treatments of airway hyperreactivity induced by hyperoxia exposure have been ineffective. The aim of this study was to investigate the effects of quercetin on hyperoxia-induced airway hyperreactivity, impaired relaxation, and lung inflammation. Newborn rats were exposed to hyperoxia (FiO2 > 95%) or ambient air (AA) for seven days. Subgroups were injected with quercetin (10 mg·kg-1·day-1). After exposures, tracheal cylinders were prepared for in vitro wire myography. Contraction to methacholine was measured in the presence or absence of organ bath quercetin and/or Nω-nitro-L-arginine methyl ester (L-NAME). Relaxation responses were evoked in preconstricted tissues using electrical field stimulation (EFS). Lung tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) levels were measured by enzyme-linked immunosorbent assay (ELISA). A P < 0.05 was considered statistically significant. Contractile responses of tracheal smooth muscle (TSM) of hyperoxic animals were significantly increased compared with AA animals (P < 0.001). Treatment with quercetin significantly reduced contraction in hyperoxic groups compared with hyperoxic control (P < 0.01), but did not have any effect in AA groups. In hyperoxic animals, relaxation of TSM was significantly reduced compared with AA animals (P < 0.001), while supplementation of quercetin restored the lost relaxation in hyperoxic groups. Incubation of preparations in L-NAME significantly reduced the quercetin effects on both contraction and relaxation (P < 0.01). Treatment of hyperoxic animals with quercetin significantly decreased the expression of TNF-α and IL-1β compared with hyperoxic controls (P < 0.001 and P < 0.01, respectively).The findings of this study demonstrate the protective effect of quercetin on airway hyperreactivity and suggest that quercetin might serve as a novel therapy to prevent and treat neonatal hyperoxia-induced airway hyperreactivity and inflammation.

Effects of Electron Radiation on Serotonin Signaling and Reactivity of Rat Gastric Smooth Muscle.

Ionizing radiation in radiotherapy can disrupt cellular functions based on radiation type, energy, and dose. However, investigations on the effects of accelerated electrons, particularly on serotonin mediation, are limited. This study aimed to investigate changes in serotonin signal transduction (targeting 5-HT2A and 5-HT2B receptors) in gastric smooth muscle (SM) samples isolated from rats irradiated with accelerated electrons (linear accelerator Siemens Primus S/N 3561) and their effects on serotonin-induced reactions. The radiation effects were examined in samples prepared five days after the procedure. The contractile activity of smooth muscle samples was measured using an isometric method. The expression of 5-HT2A and 5-HT2B receptors was determined by immunohistochemical assay. Increased contractile reactivity to exogenous serotonin (1.10-8-1.10-4 mol/L) was observed in irradiated samples compared to controls. The expression of 5-HT2A and 5-HT2B receptors was significantly increased in the irradiated tissue. By selecting appropriate time intervals between equimolar (1.10-6 mol/L) sequential serotonin exposures, a process of desensitization associated with agonist-induced internalization was established in control samples, which was absent in irradiated samples. In conclusion, irradiation with accelerated electrons affects the agonist-induced receptor internalization of 5-HT2A and 5-HT2B receptors and increases their expression in rat gastric SM, which alters their contractile reactivity to exogenous serotonin.

The Effects of Serping1 siRNA in α-Synuclein Regulation in MPTP-Induced Parkinson's Disease.

Our understanding of the gastrointestinal system in the pathophysiology of Parkinson's disease (PD) has grown considerably over the last two decades. Patients with PD experience notable gastrointestinal symptoms, including constipation. In this study, the effects of knocked-down serping1, associated with the contraction and relaxation of smooth muscle and inflammation responses, by applying the serping1 siRNA were investigated in 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine-induced PD mice in an α-syn change aspect. In the result, serping1 expression was knocked down by the treatment of serping1 siRNA, and decreased serping1 induced the decrease α-syn in the colon. Furthermore, the changes in α-syn aggregation were also examined in the brain, and alleviated α-syn aggregation was also observed in an serping1 siRNA treatment group. The results indicated that serping1 siRNA could ease synucleinopathy related to the gastrointestinal system in PD. This study also raises the possibility that serping1 siRNA could alleviate α-syn aggregation in striatum and substantia nigra regions of the brain.

Spirometric Analysis of Vitamin C and Its Effect on Lung Functions of Athletes

Commonly used vitamins such as vitamin C is seen by many athletes as nutritional supplement rather than a performance enhancing drug that boost pulmonary function parameters. This research work is aimed at investigating the effect of vitamin C on Spirometric parameters of athletes. 100 participants were used, 50 for each test group (Vitamin C) and water as control group. Spirometry and peak flow measurements were carried out on each participant. The vitamin C administered orally at a dose of 1.50mg/kg body weight and 35ml of water given orally, the body mass index (BMI), age, sex considered. Measurements were taken before and after one hour of administration of drugs. The results show mean PEFR male and female for Ascorbic Acid test group as 535.2±207.79L/Min and 322.76±20.39L/Min respectively. Control group PEFR male and female as 364.8±23.20L/Min and 325.6±20.45L/Min respectively. Control groups PEFR male and female as 450.6±51.45L/Min and 290±34.90L/Min for Vitamin C, 318±16.26L/Min and 275.20±14.77L/Min for water respectively. Vitamin C increases PEFR much more than water, ERV, IC, VC and IVC were increased by Ascorbic Acid while water decreased ERV, IC, VC, and IVC. The vitamin C effect shows a significant (p&lt;0.05) increase in PEFR, indicating a minimal response of smooth muscle to sympathomimetic. The research work supports the performance enhancing role of Vitamin C, more pronounced in males than females. The finding of this study actually shows that vitamin C indeed has beneficial effect on pulmonary function which means enhancement of performance of athletes. The relatively lower values in females in this study correspond with the report that progesterone reduces fatigue and lowers exercise tolerance (Van-Haren et al., 1998), the participants have high reserve expiratory abilities. This might be due to the fact that they are athletes, meaning they always engage in active regular bodily exercises.

Assessment of Functional Characteristics of Small Arterioles and Capillaries Using an Intact Dura Mater Preparation

The dura mater, a protective layer surrounding the brain and spinal cord, plays a crucial role in maintaining homeostatic function of the central nervous system. The large arteries and veins of the dura mater are relatively sparse and have been extensively studied with respect to their contribution to pain sensation, with unclear and controversial contributions to headache and migraine pathology. Small arterioles and capillaries exhibit nearly ubiquitous coverage of the entire dura, yet their physiological and pathophysiological functions remain largely unexplored. Here, using ex vivo mouse dura, we examined the electrical (membrane potential recordings), Ca2+ signaling properties (GCaMP or Cal-520 AM imaging), and vasomotor behavior (pressurized dura vessels with diameter measurement) of these exquisitely small vessels. Furthermore, we show electrical and Ca2+ responses in smooth muscle and pericytes in response to calcitonin gene-related peptide (CGRP) receptor and transient receptor potential V1 (TRPV1) channel activation, which are two principal targets in headache and migraine pathology. Last, we highlight unique anatomical interactions between nerves and arterioles in the dura mater using immunostaining techniques. In conclusion, we hypothesize that microvessels consisting of arterioles and capillaries are a logical and unexplored region for studying homeostatic and pathological roles of the dura mater. Funding Provided by the Totman Medical Trust This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.