Relaxation Response Research Articles

Early life adversity blunts the subjective and physiological relaxation response in healthy adults.

While Early Live Adversity (ELA) is a known risk factor for mental and physical diseases, the investigation into the mechanisms behind this connection is ongoing. In the present study, we investigated whether ELA blunts the relaxation response in healthy adults. Using a within-subjects design, we employed a paced breathing exercise (four seconds inhale, six seconds exhale) and a 360° nature video as relaxation interventions while measuring physiological relaxation using heart rate variability and subjective relaxation using the Relaxation State Questionnaire. A total of 103 participants (63.11% female; agemean = 22.73 ± 3.43years) completed the Parental Bonding Instrument and the Childhood Trauma Questionnaire to assess ELA retrospectively. For subjective relaxation, a blunted relaxation reaction was associated with lower scores of paternal care and higher scores of paternal overprotection, physical abuse, physical neglect, and emotional abuse. For heart rate variability emotional abuse in interaction with nicotine consumption was related to a blunted relaxation response. This indicates that experiencing ELA negatively affects the relaxation capability in a healthy sample and emphasizes the importance of assessing relaxation at a physiological and subjective level.

Model for the Shape of the Relaxation Spectrum in Glass Formers.

Traditionally the broadness of the spectrum of the relaxation times observed in glass-forming materials has been rationalized by local heterogeneity, where a variety of atomistic environments leads to spectrum of single-exponential relaxation responses. However, the assumption of heterogeneity can break down when tested against the shape of the relaxation spectrum. An alternative homogeneous scenario assumes that the relaxation is inherently multiexponential. A recently developed switchback model [Medvedev, G. A. Phys. Rev. E 2023, 107 (3), 034122] naturally results in a multiexponential wedge-like spectrum that is consistent with the dielectric relaxation, light scattering, and the NMR data. As a particular case the switchback model allows for the spectrum to become single-exponential; under the heterogeneous scenario this would require the heterogeneities to completely vanish, which is hard to justify. Using data from photobleaching experiments and molecular dynamic simulations, it is shown that the relaxation spectrum may become single-exponential under large anisotropic deformation. This is interpreted as an argument in favor of the homogeneous scenario and specifically the switchback model for the relaxation of the glass formers.

The effect of CD38 inhibition in age-associated vascular dysfunction

Abstract Introduction Aging is characterized by age-related vascular dysfunction, mainly caused by endothelial dysfunction and arterial stiffness. Levels of nicotinamide adenine dinucleotide (NAD) decrease with aging and accordingly, NAD is thought to be involved in the progression of age-related vascular dysfunction. Recent studies reported the involvement of CD38 in NAD regulation; indeed, its inhibition significantly prolongs the lifespan of progeroid and aged mice. However, whether CD38 is involved in the progression of age-related vascular dysfunction remains to be investigated. Methods CD38 expression was investigated in aortic homogenates of young (12-16 weeks) and aged (18-24 months) C57BL/6 wild-type mice, as well as in vitro in young (passage 5-7) and senescent (passage 14-15) primary human aortic endothelial cells (HAECs). Ex vivo tension myograph experiments were performed on thoracic aortas isolated from aged C57BL/6 mice (22-24 months old) pre-incubated for 1 hour with CD38-specific inhibitor, 78c, or DMSO as control. The effect of CD38 inhibition was also observed in vitro in senescent HAECs. Results A significant upregulation of CD38 expression was detected in the aortas of aged mice compared to the young ones as well as in senescent HAECs compared to young cells. Ex vivo tension myograph experiments showed a significant increase in endothelium-dependent relaxation responses to acetylcholine upon CD38 inhibition. The improvement of endothelial function was prevented by the addition of endothelial nitric oxide synthase (eNOS) inhibitor (L-NAME), but not by the COXs inhibitor, indomethacin, indicating that the observed effect achieved by CD38 inhibition is eNOS dependent. The involvement of the eNOS pathway was further supported by the in vitro finding in HAECs of increased eNOS activation upon CD38 inhibition. Conclusion The herein-reported data suggests an involvement of CD38 in the development of age-related endothelial dysfunction. Further studies are ongoing to investigate the underlying molecular mechanisms as well as the effect of long-term CD38 inhibitor supplementation on the progression of age-related vascular dysfunction.

Sirt5 as a mediator of endothelial and vascular dysfunction: potential therapeutic target in aging-related vascular diseases

Abstract Background Aging is one of the most dominant cardiovascular (CV) risk factors. Sirt5 belongs to the lifespan-regulating sirtuin superfamily as a protein deacylase. However, its regulatory effects on vascular function and aging are yet unclear. Purpose We therefore aimed to investigate the roles of Sirt5 on endothelial and vascular function during aging, decipher the underlying mechanisms, and to explore its potential as a therapeutic target through in vivo and in vitro studies. Methods Aortic expression of Sirt5 were studied in C5BL/6 wild type (WT) mice during aging, followed by vascular functional and structural assessment in WT mice and Sirt5-overexpressing mice (Sirt5/Tg) using the established myograph system and histological staining respectively. Furthermore, the regulatory role of Sirt5 on endothelial function was investigated in senescent primary human aortic endothelial cells (HAECs, passages 13-15) by studying its interference with endothelial nitric oxide synthase (eNOS) expression and activity in knock-down experiments using siRNA. The therapeutic potential of Sirt5 inhibition was explored at the tissue level in myograph experiments. Results Aged WT mice had increased level of Sirt5 in aorta compared to the young ones. Overexpression of Sirt5 in vivo led to significantly reduced aortic endothelial-dependent relaxation and displayed thicker collagen deposition in the adventitia compared to aged WT controls. The reduction of vascular relaxing response in Sirt5/Tg mice was prevented by an addition of eNOS inhibitor (L-name), indicating that Sirt5 regulated vascular function through the eNOS pathway. In senescent HAECs, knock-down of Sirt5 markedly induced total eNOS expression and increased its activity (phospho-eNOS Ser1177), further confirming the regulatory role of Sirt5 on eNOS pathway. In line with the above, aorta from aged WT mice displayed improved endothelial function after pharmacological inhibition of Sirt5. Conclusion Vascular Sirt5 expression increases with age and contributes to aging-related endothelial dysfunction by downregulating the eNOS pathway. Thus, Sirt5 inhibition may represent a novel therapeutic approach to maintain vascular function during aging. Ongoing studies will investigate Sirt5 silencing in-vivo using RNA interference for its therapeutic potential to prevent aging-related vascular dysfunction.

Exploring the interplay of urban form and greenery in residents’ affective and cognitive responses

Stress is a prevalent issue in modern cities, exacerbated by urban development and significantly affecting urban dwellers. While it is known that greenery can contribute to people’s wellbeing, it is unclear if it can mitigate the negative effects of urban development. In this study, we aim to explore the intricate dynamics between urban form and greenery to dissect their collective effect on human wellbeing, operationalized through physiological relaxation, preference, and emotional responses. The study employs an experimental study design using virtual reality technology to immerse participants (n=156) into residential neighborhood scenes, and measures affective and cognitive responses using skin conductance measures and a survey, respectively. In general, the findings confirm the critical role of urban greenery on affective and cognitive responses. Interestingly, we observe that this effect is highly dependent on the context and shows diverging patterns between different neighborhood types. In particular, in certain neighborhoods (popular, 60 s, and cooperative), greenery, no matter if species-poor or biodiverse, consistently improves preference and physiological relaxation. In contrast, urban centers and single-family residential areas may accommodate more biodiverse green spaces without compromising their existing high preference levels when compared to less affluent neighborhoods. The study concludes with a call for urban planning to cultivate equitable, green, and distinctively designed urban environments. This shift underscores the critical role of innovative urban design in improving the wellbeing of urban dwellers.

Differential expression of components of the CGRP-receptor family in human coronary and human middle meningeal arteries: functional implications

BackgroundDifferent responses in human coronary arteries (HCA) and human middle meningeal arteries (HMMA) were observed for some of the novel CGRP receptor antagonists, the gepants, for inhibiting CGRP-induced relaxation. These differences could be explained by the presence of different receptor populations in the two vascular beds. Here, we aim to elucidate which receptors are involved in the relaxation to calcitonin gene-related peptide (CGRP), adrenomedullin (AM) and adrenomedullin 2 (AM2) in HCA and HMMA.MethodsRNA was isolated from homogenized human arteries (23 HCAs; 12 F, 11 M, age 50 ± 3 years and 26 HMMAs; 14 F, 12 M, age 51 ± 3 years) and qPCR was performed for different receptor subunits. Additionally, relaxation responses to CGRP, AM or AM2 of the human arteries were quantified using a Mulvany myograph system, in the presence or absence of the adrenomedullin 1 receptor antagonist AM22-52 and/or olcegepant.ResultsCalcitonin-like receptor (CLR) mRNA was expressed equally in both vascular beds, while calcitonin receptor (CTR) and receptor activity-modifying protein 3 (RAMP3) expression was low and could not be detected in all samples. RAMP1 expression was similar in HCA and HMMA, while RAMP2 expression was higher in HMMA. Moreover, receptor component protein (RCP) expression was higher in HMMA than in HCA. Functional experiments showed that olcegepant inhibits relaxation to all three agonists in both vascular beds. In HCA, antagonist AM22-52 did not inhibit relaxation to any of the agonists, while a trend for blocking relaxation to AM and AM2 could be observed in HMMA.ConclusionBased on the combined results from receptor subunit mRNA expression and the functional responses in both vascular tissues, relaxation of HCA is mainly mediated via the canonical CGRP receptor (CLR-RAMP1), while relaxation of HMMA can be mediated via both the canonical CGRP receptor and the adrenomedullin 1 receptor (CLR-RAMP2). Future research should investigate whether RAMP2 predominance over RAMP1 in the meningeal vasculature results in altered migraine susceptibility or in a different response to anti-migraine medication in these patients. Moreover, the exact role of RCP in CGRP receptor signalling should be elucidated in future research.

Improving Mental Health Outcome in Hypertensive Patients: The Role of Relaxation Techniques

Background: Relaxation techniques (progressive muscle relaxation and deep breathing) have an impact on the patients with hypertension as they produce a relaxation response within the body and thus, are efficient in lowering the stress and blood pressure in the patients. Objective: This study aims to determine the role of relaxation techniques (progressive muscle relaxation and deep breathing) on improving mental health outcome in hypertensive patients (depression, anxiety and stress). Methodology: A Quasi-experimental design used to guide this study, it was conducted by use of a pre-posttest approach during the period 26th of November, 2023 to 7th of April, 2024. A non-probability (purposive) sampling has been performed during a selection of (100) patients who attending Outpatient Clinic in Al-Diwaniyah Teaching Hospital, (50) patients as control group and (50) patients as study group. The researcher used a socio-demographic and psychological parameter scale (DASS-21). Results: The findings of the current study show highly statistically significant differences in post-test between study and control group (at P ≤ 0.001). On other hand, there is no statistically significant difference in the pre-test between the two group of all psychological parameter (at P ≤ 0.05). Conclusion: Based on the study's findings, progressive muscle relaxation and deep breathing exercises can both proved to be significantly effective in improve mental health in hypertensive patients (depression, anxiety and stress). Recommendations: In order to reduce hypertension and other psychological parameters in patients with essential hypertension, the researcher suggested combining pharmacological therapies with non-drug therapy (relaxation techniques intervention) in the management of hypertension.

"Evaluation of the effects of pioglitazone on perivascular adipose tissue function, properties and structure in a rat model of type-2 diabetes."

Perivascular adipose tissue (PVAT) plays an important role in many physiological and pathological processes, such as regulation of vascular tone. The aim of this study is to evaluate the effects of pioglitazone on functional, structural, and biochemical properties of PVAT in an experimental model of type-2 diabetes (T2DM). T2DM was induced by high-fat-diet/low-dose-streptozotocin (HFD/STZ) in rats, and pioglitazone (20mg/kg/p.o.) was administered for 6 weeks. Changes in biochemical parameters, PVAT-mass, vascular-reactivity in thoracic-aorta as well as PVAT adipocytokine and PPARG-expression levels, and histopathology were evaluated. Pioglitazone administration improved blood glucose and lipid profiles in T2DM. Pioglitazone did not change the anticontractile effect of PVAT on aortic contractile reactivity and besides, had no influence on endothelium-dependent and -independent relaxation responses. Pioglitazone administration increased PVAT-mass and TNF-α levels while adiponectin, leptin, and IL-6 levels were unchanged. Also, a prominent increase was observed in PPARG-expression in T2DM-Pio group. Moreover, pioglitazone decreased liver steatosis, aortic wall thickening and myocardial damage whereas increased adipocyte size and adiposity in PVAT. Overall, pioglitazone treatment changed the mass and in part the inflammatory profile of PVAT but did not modify vasoreactivity in T2DM. This study provides novel findings in relationship with the adipogenic effect of pioglitazone and PVAT function.

Sacubitril/Valsartan Combination Partially Improves Cardiac Systolic, but Not Diastolic, Function through β-AR Responsiveness in a Rat Model of Type 2 Diabetes

Cardiovascular complications are the major cause of diabetes mellitus-related morbidity and mortality. Increased renin–angiotensin–aldosterone system activity and decreased β-adrenergic receptor (β-AR) responsiveness contribute to diabetic cardiac dysfunction. We evaluated the effect of sacubitril/valsartan (neprilysin inhibitor plus angiotensin receptor antagonist combination) and valsartan treatments on the diabetic cardiac function through β-AR responsiveness and on protein expression of diastolic components. Six-week-old male Sprague Dawley rats were divided into control, diabetic, sacubitril/valsartan (68 mg/kg)-, and valsartan-treated (31 mg/kg) diabetic groups. Diabetes was induced by a high-fat diet plus low-dose streptozotocin (30 mg/kg, intraperitoneal). After 10 weeks of diabetes, rats were treated for 4 weeks. Systolic/diastolic function was assessed by in vivo echocardiography and pressure–volume loop analysis. β-AR-mediated responsiveness was assessed by in vitro papillary muscle and Langendorff heart experiments. Protein expression of sarcoplasmic reticulum calcium ATPase2a, phospholamban, and phosphorylated phospholamban was determined by Western blot. Sacubitril/valsartan improved ejection fraction and fractional shortening to a similar extent as valsartan alone. None of the treatments affected in vivo diastolic parameters or the expression of related proteins. β1-/β2-AR-mediated responsiveness was partially restored in treated animals. β3-AR-mediated cardiac relaxation (an indicator of diastolic function) responses were comparable among groups. The beneficial effect of sacubitril/valsartan on systolic function may be attributed to improved β1-/β2-AR responsiveness.

Chronic Pain Psychology in Neurology Practice

ABSTRACT OBJECTIVE This article reviews the latest literature regarding chronic pain epidemiology and describes pain-specific psychological factors associated with the development and maintenance of chronic pain, mental health conditions that co-occur with chronic pain, and advances in the psychobehavioral treatment of chronic pain, including established treatments (ie, cognitive behavioral therapy [CBT], acceptance and commitment therapy, and mindfulness-based stress reduction) and emerging treatments (ie, pain reprocessing therapy). LATEST DEVELOPMENTS In addition to CBT and acceptance and commitment therapy for pain, numerous other psychological treatment modalities have been integrated into chronic pain management, including mindfulness-based stress reduction, mindfulness meditation, chronic pain self-management, relaxation response, pain neuroscience education, biofeedback, hypnosis, and, more recently, integrative psychological treatment for centralized pain. This article gives an overview of these methods and contextualizes their use within the standard psychological treatment of chronic pain. ESSENTIAL POINTS Guided by the biopsychosocial treatment model, pain psychologists use numerous evidence-based psychological methods to treat patients with chronic pain conditions. Familiarity with the psychological tools available for pain management will aid neurologists and their patients in navigating the psychological aspects of living with chronic pain.

Knockout of Sirtuin 3 in endothelial cells impairs endothelial-dependent relaxation and myogenic response in mice.

Sirtuin 3 has been shown to regulate endothelial function and coronary flow reserve in mice. Knockout of SIRT3 reduced endothelial nitric oxide synthase expression in the mouse hearts. In this study, we investigate whether endothelial SIRT3 regulates vascular function and myogenic responses in distal intramural branches of the left anterior descending coronary artery (CA) and middle cerebral artery (MCA) of mice. Both male and female endothelial SIRT3 knockout (SIRT3ECKO) mice and control SIRT3LoxP mice were used and CA and MCA were dissected and mounted in a myograph system. The myogenic response was evaluated by measuring changes in inner diameter in response to 20 mmHg stepwise increases in intraluminal pressure in PSS (active diameter) and Ca2+-free PSS (passive diameter). Acetylcholine (Ach)-induced endothelial-dependent relaxation (EDR) and sodium nitroprusside (SNP)-induced endothelial-independent relaxation (EIR) were examined. Our results showed that the myogenic responses were significantly impaired in both the CA and MCA of SIRT3ECKO mice. Furthermore, female mice had worsened myogenic response in MCA. In CA, EDR was abolished in both male and female SIRT3ECKO mice. Intriguingly, EIR was only reduced in the female mice. In MCA, EDR was reduced in male SIRT3ECKO mice, whereas EIR was decreased in both male and female mice. Female SIRT3ECKO mice had profound dysfunction in CA, whereas male mice exhibited more dysfunction in MCA. These data revealed a sex and organ-specific role of endothelial SIRT3 in vascular function and myogenic responses. Our study suggests that endothelial SIRT3 is necessary for maintaining vascular function and blood flow autoregulation.

SUMOylation of cardiac myosin binding protein-C reduces its phosphorylation and results in impaired relaxation following treatment with isoprenaline

Systolic and diastolic functions are coordinated in the heart by myofilament proteins that influence force of contraction and calcium sensitivity. Fine control of these processes is afforded by a variety of post-translation modifications that occur on specific proteins at different times during each heartbeat. Cardiac myosin binding protein-C is a sarcomeric accessory protein whose function is to interact transiently with actin, tropomyosin and myosin. Previously many different types of post-translational modification have been shown to influence the action of myosin binding protein-C and we present the first report that the protein can be modified covalently by the small ubiquitin like modifier protein tag. Analysis by mass spectrometry suggests that there are multiple modification sites on myosin binding protein-C for this tag and single point mutations did not serve to abolish the covalent addition of the small ubiquitin like modifier protein. Functionally, our data from both model human embryonic kidney cells and transfected neonatal cardiac myocytes suggests that the modification reduces phosphorylation of the filament protein on serine 282. In cardiac myocytes, the hypo-phosphorylation coincided with a significantly slower relaxation response following isoprenaline induced contraction. We hypothesise that this novel modification of myosin binding protein-C represents a new level of control that acts to alter the relaxation kinetics of cardiac myocytes.

Improvements in Pain Interference among Geographically Diverse Adults with Neurofibromatosis: Results from a Fully-Powered Randomized Controlled Trial

Abstract Background Pain is prevalent among adults with Neurofibromatoses (NF) and hinders quality of life. Pain management for NF is predominantly pharmacological and often ineffective. Psychosocial treatments improve pain outcomes in other chronic illness populations but have not been developed and tested in fully powered efficacy trials among adults with NF. Using data from a fully powered RCT of an 8-week mind-body program (Relaxation Response Resiliency Program for NF [3RP-NF]) versus a health education control (HEP-NF), we examined: 1) improvements in pain intensity and pain interference, and 2) mechanisms underlying improvements. Methods Participants (N=210, Mage=42.6, 73.4% female) were randomized to 3RP-NF vs HEP-NF. They completed measures of pain intensity, pain interference, and putative mechanisms (e.g., mindfulness, coping, and social support) at baseline, post-intervention, 6-month, and 12-month follow-up. Results There was a statistically significant change in pain interference over time F(3, 537.06)=7.21, p<.001, but not pain intensity. Neither group (3RP-NF vs. HEP-NF) nor the group-by-time interaction predicted change in pain interference. While the group-by-time interaction was not statistically significant across all time points, planned post-hoc analyses probing the interaction at specific time points revealed a statistically significant decrease in pain interference from baseline to post-intervention (p<.001), which was sustained (i.e., no subsequent change) from post-intervention through 6-month (p=1.00) and 12-month follow-ups (p=1.00) in the 3RP-NF group. The HEP-NF group had no significant changes in pain intensity or interference over time. The association between group (3RP-NF) and decreased pain interference from baseline to post-intervention was fully mediated by change in coping over the same period. Conclusions Participation in the 3RP-NF is associated with sustained improvement in pain interference. Improvement occurred through increased coping.

Detection of invasive ductal carcinoma by electrical impedance spectroscopy implementing gaussian relaxation-time distribution (EIS-GRTD)

Breast cancer detection and differentiation of breast tissues are critical for accurate diagnosis and treatment planning. This study addresses the challenge of distinguishing between invasive ductal carcinoma (IDC), normal glandular breast tissues (nGBT), and adipose tissue using electrical impedance spectroscopy combined with Gaussian relaxation-time distribution (EIS-GRTD). The primary objective is to investigate the relaxation-time characteristics of these tissues and their potential to differentiate between normal and abnormal breast tissues. We applied a single-point EIS-GRTD measurement to ten mastectomy specimens across a frequency range f = 4 Hz to 5 MHz. The method calculates the differential ratio of the relaxation-time distribution function Δγ between IDC and nGBT, which is denoted by ΔγIDC−nGBT, and Δγ between IDC and adipose tissues, which is denoted by ΔγIDC−adipose. As a result, the differential ratio of Δγ between IDC and nGBT ΔγIDC−nGBT is 0.36, and between IDC and adipose ΔγIDC−adipose is 0.27, which included in the α -dispersion at τpeak1=0.033±0.001s. In all specimens, the relaxation-time distribution function γ of IDC γIDC is higher, and there is no intersection with γ of nGBT γnGBT and adipose γadipose. The difference in γ suggests potential variations in relaxation properties at the molecular or structural level within each breast tissue that contribute to the overall relaxation response. The average mean percentage error δ for IDC, nGBT, and adipose tissues are 5.90%, 6.33%, and 8.07%, respectively, demonstrating the model’s accuracy and reliability. This study provides novel insights into the use of relaxation-time characteristic for differentiating breast tissue types, offering potential advancements in diagnosis methods. Future research will focus on correlating EIS-GRTD finding with pathological results from the same test sites to further validate the method’s efficacy.

Theoretical analysis of the structure, thermodynamics, and shear elasticity of deeply metastable hard sphere fluids.

The structure, thermodynamics, and slow activated dynamics of the equilibrated metastable regime of glass-forming fluids remain a poorly understood problem of high theoretical and experimental interest. We apply a highly accurate microscopic equilibrium liquid state integral equation theory, in conjunction with naïve mode coupling theory of particle localization, to study in a unified manner the structural correlations, thermodynamic properties, and dynamic elastic shear modulus in deeply metastable hard sphere fluids. Distinctive behaviors are predicted including divergent inverse critical power laws for the contact value of the pair correlation function, pressure, and inverse dimensionless compressibility, and a splitting of the second peak and large suppression of interstitial configurations of the pair correlation function. The dynamic elastic modulus is predicted to exhibit two distinct exponential growth regimes with packing fraction that have strongly different slopes. These thermodynamic, structural, and elastic modulus results are consistent with simulations and experiments. Perhaps most unexpectedly, connections between the amplitude of long wavelength density fluctuations, dimensionless compressibility, local structure, and the dynamic elastic shear modulus have been theoretically elucidated. These connections are more broadly relevant to understanding the slow activated relaxation and mechanical response of colloidal suspensions in the ultradense metastable region and deeply supercooled thermal liquids in equilibrium.

PSII-12 The effect of the diffusion of geranium and clary sage essential oils on relaxation responses in horses

Abstract Aromatherapy has been used in holistic medicine to improve relaxation in humans; however, there are limited studies on its use in horses. This study investigated the potential of aromatherapy on relaxation responses in horses using two common essential oils geranium (Pelargonium asperum) and clary sage (Salvia sclarea). We hypothesized that aromatherapy using essential oils would improve relaxation responses in horses. Geranium aromatherapy (GA) and clary-sage aromatherapy (CA) were tested against a control (CO; deionized water only) in a replicated 3 x 3 Latin square with three treatments, three horses (584 ± 9 kg of body weight and 11 ± 1 yr old), and three experimental periods. The experiment was replicated using the same horses, and the two experimental replicates were considered the square blocking factor. Aromatherapy session involved a 5-min acclimation period followed by 15 min of aromatherapy using a diffusor. Heart rate and respiration rate at min 0, 7 and 15, and average counts for body position and facial expressions from min 0 to 7 and from 7 to 15 (early and late session, respectively) were used as measure of relaxation. Aromatherapy improved eye expression over time (P = 0.01), with GA and CA horses showing significantly increased durations of relaxed eyes from early to late session (2.8 min vs. 5.3 min for GA and 3.7 min vs. 4.8 min for CA), while horses on CO showed reduced duration from early to late session (2.7 min vs. 1.2 min), indicating increased level of alertness and tension. Aromatherapy tended (P = 0.07) to improve ear expression. Horses receiving CA tended to show longer durations of relaxed ears compared with CO (4.33 min vs. 1.25 min), while GA (3.25 min) did not differ from CA and CO. Aromatherapy did not affect (P > 0.05) measures of body posture and heart and respiratory rates. Although not all relaxation responses were improved by aromatherapy, the results indicate that aromatherapy has potential for improving relaxation in horses as indicated by facial expressions.

THE effect of P2X7 receptor activation on functional responses of human left internal mammary artery.

The Purinoreceptor 7 (P2X7R) has become a promising drug target in many cardiovascular diseases, including coronary artery disease, since prolonged activation of P2X7R could promote vascular dysfunction, atherosclerosis, and thrombosis. Thus, we aimed to study the effects of P2X7R activation on vascular relaxation responses of the human left internal mammary artery (LIMA). Sections of redundant human LIMA were cut into 3-mm wide rings,, suspended in 20-mL organ baths containing physiologic salt solution, and attached to an isometric force transducer connected to a computer-based data acquisition system. Long-term (60min) incubation with specific P2X7R agonist Bz-ATP caused significant reductions in relaxation responses of LIMA to ATP and acetylcholine, which were reversed by selective P2X7R antagonists Brilliant Blue G or AZ11645373, whereas there were no changes in relaxation responses to endothelium-independent vasodilators isoprenaline, cAMP analog 8-Br-cAMP, and nitric oxide donor sodium nitroprusside. The impairment in relaxant responses of LIMA to endothelium-dependent vasodilators following activation of P2X7R for the long-term may contribute to postoperative LIMA vasospasm and hypertension. Modulation of P2X7R activity with selective agents may represent a new potential therapeutic approach in patients undergoing coronary artery bypass grafting surgery.

Abstract P456: Loss of Renal Resident Tissue Macrophages Reduces Nitric Oxide-Mediated Relaxation during Salt-Sensitive Hypertension

Salt-sensitive hypertension (SS-HTN) associates with increased renal sodium reabsorption, arterial dysfunction, and heightened pro-inflammatory cytokines such as interleukin 6 (IL-6). Renal resident tissue macrophages (rRTMs) function to both maintain tissue homeostasis and once activated, can secrete IL-6. We reported that loss of the rRTM population prevents SS-HTN but their influence on arterial reactivity has not been tested. We hypothesize that rRTM-induced IL-6 production impairs endothelial function. Wild-type (Wt) or rRTM-depleted (CX 3 CR 1 - EGFP+/+ ) male mice (12wks) were used. Mice were given the nitric oxide synthase (NOS) inhibitor, L-NAME (0.5mg/mL, in drinking water, 2wks) and allowed to washout (1-2wks) before fed normal chow (NC), high salt (HS) chow (4%) for 2 days (early salt-sensitive, eSS) or for 3wks HS (SS-HTN). eSS mice were salt-sensitive, but not yet hypertensive. Mice were also given HS chow alone (3wks). Serum was collected for systemic cytokines (Meso-Scale Discovery; n=4-15) and second-order mesenteric resistance arteries (MRAs) were obtained (n=3-5). Concentration response curves (CRCs) to phenylephrine (Phe) and acetylcholine (ACh) were performed in the presence or absence of potassium chloride (KCl) or L-NMMA. Serum IL-6 levels were not increased following HS diet alone, but concentrations trended higher during SS-HTN (1.46 ± 0.2 pg/mL vs. 1.07 ± 0.2 pg/mL NC). The nadir was observed in eSS mice, before the development of SS-HTN, and was prevented in rRTM-depleted mice (1.81 ± 0.3 pg/mL vs. 0.58 ± 0.17, **p<0.001, grouped ANOVA). No differences were observed between NC-fed Wt and rRTM-depleted MRAs, but the development of SS-HTN did impair relaxation responses. Overall, ACh-mediated relaxation responses were generally lower in MRAs from rRTM-depleted mice compared to Wt. Interestingly, rRTM-depleted MRAs from SS-HTN animals exhibited a near complete inhibition of all relaxation responses with NOS inhibition (R max 6.20% ± 8 rRTM SS-HTN vs. 63.0% ± 10 Wt SS-HTN, *p<0.05), suggesting greater dependence on NO-mediated relaxation. Together, these data suggest that rRTMs contribute to an early, hypertension-independent spike in IL-6 which may reduce endothelial function later during SS-HTN. We also show that rRTM-depletion affects the function of the resistance vasculature, including loss of non-NO-mediated relaxation during SS-HTN. These data suggest that renal-derived cytokines, via rRTMs, may influence endothelial function.

Abstract P231: Self-administration of Remifentanil Induces Endothelial Dysfunction in Thoracic Aorta and Impaired Cavernosal Reactivity of Wistar Rats

Aims: Recent studies have implicated the use of prescription opioids as a risk factor for cardiovascular diseases (CVD), with associations including myocardial infarction, coronary artery disease and vascular deterioration. Further, opioid-dependent patients show increased vascular aging and arterial stiffness when compared to opioid-naïve controls. Our hypothesis was that rats dependent on remifentanil (a fentanyl analog) after a 12-day operant self-administration (SA) study lead to vascular dysfunction in thoracic aorta. Because erectile dysfunction (ED) is associated with arterial stiffness and is positively correlated with its severity, we hypothesized that opioid SA impaired corpus cavernosum (CC) reactivity as well. Methods: Male Wistar rats (12 weeks-old) were implanted with intravenous catheters and learned to lever press (FR1) for remifentanil (1µg/kg/infusion). A separate group of rats received passive yoked infusions of saline administered in synchrony with remifentanil-treated animals to control volumetric vascular effects. Following administration, animals were euthanized, and aorta and CC collected to evaluate function using both pin and strip myographs. Concentration-response curves to phenylephrine (Phe; 10 -11 -10 -4 M), sodium nitroprusside (SNP) and acetylcholine (Ach or SNP; 10 -10 -10 -4 M) were performed to test contractility and endothelium-independent and -dependent relaxation respectively. Results: Remifentanil-treated rats showed rapidly acquired SA behavior, exhibiting robust and selective drug-paired lever pressing when compared to the non-drug paired lever. In contrast, yoked saline-treated controls rarely exhibited lever pressing. Endothelium-dependent relaxation in the aorta was diminished in the remifentanil group (Rmax: Control: 68.7±2.7 vs. Remi: 47.8±3.7%; p<0.05). There were no observed alterations in endothelium-independent relaxation or vascular contraction. However, CC contraction was slightly shifted to the right in remifentanil treated rats (pEC 50 : Control: 6.04±0.09 vs. Remi: 5.66±0.12; p<0.05). No changes were observed in the CC relaxant response. These findings indicate that 12 days of remifentanil administration results in endothelial dysfunction in large arteries and impaired cavernosal reactivity. Long-term exposure may lead to aortic stiffness exacerbating ED severity and increases in pulse-wave velocity in opioid-dependent patients contributing to the onset of hypertension.

Functional anticholinergic activity of drugs classified as strong and moderate on the anticholinergic burden scale on bladder and ileum.

Several medications are commonly administered to older Japanese patients. Since some of them have not been included in previously developed scales to estimate the anticholinergic burden, we have developed a new muscarinic receptor binding-based anticholinergic burden scale. This study aimed to investigate the functional inhibitory effects of 60 medications, classified as anticholinergic burden scales 3 and 2 by the anticholinergic burden scale, on muscarinic receptor-mediated contractions in the bladder and ileum. The relaxation response induced by these drugs on isolated rat bladders and ileum smooth muscles constricted by carbachol was assessed using the organ bath method. All drugs inhibited smooth muscle contractile responses induced by the muscarinic receptor activation in a concentration-dependent manner in the rat bladder and ileum. Notably, variations were observed in the relaxation responses of the drugs, and the function EC50 values were positively correlated with the binding IC50 values in the bladder and ileum. The results of this study provide functional pharmacological evidence for the muscarinic receptor binding-based anticholinergic burden scale. Implementation of this scale may help reduce the risk of constipation and urinary retention, which are common side effects associated with anticholinergic drugs.