Adrenergic Receptor Stimulation Research Articles

Protein carbonylation causes sarcoplasmic reticulum Ca2+ overload by increasing intracellular Na+ level in ventricular myocytes.

Diabetes is commonly associated with an elevated level of reactive carbonyl species due to alteration of glucose and fatty acid metabolism. These metabolic changes cause an abnormality in cardiac Ca2+ regulation that can lead to cardiomyopathies. In this study, we explored how the reactive α-dicarbonyl methylglyoxal (MGO) affects Ca2+ regulation in mouse ventricular myocytes. Analysis of intracellular Ca2+ dynamics revealed that MGO (200 μM) increases action potential (AP)-induced Ca2+ transients and sarcoplasmic reticulum (SR) Ca2+ load, with a limited effect on L-type Ca2+ channel-mediated Ca2+ transients and SERCA-mediated Ca2+ uptake. At the same time, MGO significantly slowed down cytosolic Ca2+ extrusion by Na+/Ca2+ exchanger (NCX). MGO also increased the frequency of Ca2+ waves during rest and these Ca2+ release events were abolished by an external solution with zero [Na+] and [Ca2+]. Adrenergic receptor activation with isoproterenol (10nM) increased Ca2+ transients and SR Ca2+ load, but it also triggered spontaneous Ca2+ waves in 27% of studied cells. Pretreatment of myocytes with MGO increased the fraction of cells with Ca2+ waves during adrenergic receptor stimulation by 163%. Measurements of intracellular [Na+] revealed that MGO increases cytosolic [Na+] by 57% from the maximal effect produced by the Na+-K+ ATPase inhibitor ouabain (20 μM). This increase in cytosolic [Na+] was a result of activation of a tetrodotoxin-sensitive Na+ influx, but not an inhibition of Na+-K+ ATPase. An increase in cytosolic [Na+] after treating cells with ouabain produced similar effects on Ca2+ regulation as MGO. These results suggest that protein carbonylation can affect cardiac Ca2+ regulation by increasing cytosolic [Na+] via a tetrodotoxin-sensitive pathway. This, in turn, reduces Ca2+ extrusion by NCX, causing SR Ca2+ overload and spontaneous Ca2+ waves.

Inhibition of ezrin phosphorylation by NSC305787 attenuates procaterol-stimulated ciliary beating in airway cilia

Ciliary beating in the airway epithelium plays an important role in preventing infection by eliminating small particles and pathogens. Stimulation of β2 adrenergic receptor (β2AR) increases [cAMP]i levels and strongly activates this ciliary beating. β2AR is localized to the apical membrane of the airways by indirectly binding to ezrin, an actin-binding protein. Ezrin takes active phosphorylated and inactive dephosphorylated states at Thr-567. Previously we showed that procaterol-stimulated ciliary beating was impaired in the ezrin-knockdown mice. In this study, we examined the roles of ezrin and its phosphorylation in regulating ciliary beating by using NSC305787, an ezrin inhibitor, in normal human airway epithelial cells (NHBE). We found that NSC305787 inhibits the phosphorylation of ezrin with an IC50 of 50 μM in NHBE. Treatment with NSC305787 for 4 h or more decreased the expression of β2AR in the cell membrane and induced vesicle- or dot-like expression of ezrin and β2AR inside the cell. As a result, inhibition of ezrin phosphorylation by NSC305787 attenuated the effect of procaterol-induced activation of ciliary beating in both frequency and distance indices.

Unveiling Catecholamine Dynamics in Cardiac Health and Disease: Mechanisms, Implications, and Future Perspectives

Review Unveiling Catecholamine Dynamics in Cardiac Health and Disease: Mechanisms, Implications, and Future Perspectives Wenjing Xiang, Xingyun Wang, Lei Li, Junhui Zeng, Haocheng Lu, and Ying Wang * Department of Pharmacology, School of Medicine, Southern University of Science and TechnologyShenzhen518055China * Correspondence: wangy6@sustech.edu.cn Received: 15 August 2023 Accepted: 21 September 2023 Published: 27 December 2023 Abstract: Catecholamines play a pivotal role in regulating both cardiac physiology and pathology, orchestrating the “Fight-or-flight” response through the activation of sympathetic nervous system (SNS) activation and subsequent stimulation of adrenergic receptor. However, chronic stress and various cardiac diseases can disrupt catecholamine balance, contributing to cardiac dysfunction. The synthesis, release, reuptake, and degradation of catecholamines intricately regulate their concentration. Notably, catecholamine dynamics is markedly altered in heart diseases, including heart failure, myocardial infarction, and arrhythmias. While β‍-adrenergic receptor blockers, which block catecholamines from binding to the adrenergic receptors, are widely used in clinical settings, the potential implication of directly manipulating catecholamine homeostasis for the treatment of cardiac diseases have not been extensively explored. This review provides an overview of catecholaminergic systems, and discusses their intricate synthesis, release, uptake, and metabolism within the heart. Additionally, the review highlights mechanisms underlying cardiac effects of catecholamine dysregulation, including contractile dysfunction, electrical remodeling, and cardiac remodeling. Moreover, the review emphasizes the importance of considering spatiotemporal and sexual heterogeneity in catecholamine dynamics for cardiac precision medicine. In terms of future perspectives, we believe that harnessing genetically encoded fluorescent biosensors to map the heterogenous for real-time imaging of catecholamine dynamics and conducting gender-specific dissection of catecholamine dynamics have significant potential to advance personalized management of cardiac diseases management.

Cardiovascular physiology of embryonic neotropic cormorants (Phalacrocorax brasilianus)

Cardiovascular maturation in avian species has primarily been studied in precocial species of birds, with few studies conducted on altricial species, which make up the majority of avian species. In the precocial species of birds studied to date, cardiovascular regulation is derived primarily from an adrenergic receptor stimulation that is present from approximately 50% to 60% of incubation until hatching. Conversely, the cholinergic modulation of heart rate differs in its timing of activation, as it is reported to be present in some studies at 60% of incubation to as late as after hatching in others. This has led to the speculation that, although adrenergic stimulation is critical to cardiovascular homeostasis, cholinergic stimulation prior to hatching in birds is species-specific and therefore is not critical for cardiovascular homeostasis in embryonic birds. In this work, we conducted a series of studies on an altricial species, the neotropic cormorant (Phalacrocorax brasilianus), to gain novel data regarding cardiovascular development in a largely unstudied group of birds. We investigated cholinergic and adrenergic receptor mediated control of both arterial blood pressure and heart rate. We predicted that, given the state of this altricial species at hatching, both cholinergic and adrenergic tone on the cardiovascular system would be functional in the embryo. Our findings indicate that cholinergic tone was present at 90% of incubation. However, there was a pronounced adrenergic tone on the cardiovascular system that was relatively greater than that reported in the other studies of avian embryos. Therefore, our findings support our prediction regarding the function of cholinergic tone and adrenergic tone prior to hatching.

Sympathetic activity regulates epithelial proliferation and wound healing via adrenergic receptor α2A

Innervation of the intestinal mucosa by the sympathetic nervous system is well described but the effects of adrenergic receptor stimulation on the intestinal epithelium remain equivocal. We therefore investigated the effect of sympathetic neuronal activation on intestinal cells in mouse models and organoid cultures, to identify the molecular routes involved. Using publicly available single-cell RNA sequencing datasets we show that the α2A isoform is the most abundant adrenergic receptor in small intestinal epithelial cells. Stimulation of this receptor with norepinephrine or a synthetic specific α2A receptor agonist promotes epithelial proliferation and stem cell function, while reducing differentiation in vivo and in intestinal organoids. In an anastomotic healing mouse model, adrenergic receptor α2A stimulation resulted in improved anastomotic healing, while surgical sympathectomy augmented anastomotic leak. Furthermore, stimulation of this receptor led to profound changes in the microbial composition, likely because of altered epithelial antimicrobial peptide secretion. Thus, we established that adrenergic receptor α2A is the molecular delegate of intestinal epithelial sympathetic activity controlling epithelial proliferation, differentiation, and host defense. Therefore, this receptor could serve as a newly identified molecular target to improve mucosal healing in intestinal inflammation and wounding.

Secondary diabetes mellitus in pheochromocytomas and paragangliomas.

Secondary diabetes mellitus (DM) in secretory pheochromocytomas and paragangliomas (PPGLs) is encountered in up to 50% of cases, with its presentation ranging from mild, insulin resistant forms to profound insulin deficiency states, such as diabetic ketoacidosis and hyperglycemic hyperosmolar state. PPGLs represent hypermetabolic states, in which adrenaline and noradrenaline induce insulin resistance in target tissues characterized by aerobic glycolysis, excessive lipolysis, altered adipokine expression, subclinical inflammation, as well as enhanced gluconeogenesis and glucogenolysis. These effects are mediated both directly, upon adrenergic receptor stimulation, and indirectly, via increased glucagon secretion. Impaired insulin secretion is the principal pathogenetic mechanism of secondary DM in this setting; yet, this is relevant for tumors with adrenergic phenotype, arising from direct inhibitory actions in beta pancreatic cells and incretin effect impairment. In contrast, insulin secretion might be enhanced in tumors with noradrenergic phenotype. This dimorphic effect might correspond to two distinct glycemic phenotypes, with predominant insulin resistance and insulin deficiency respectively. Secondary DM improves substantially post-surgery, with up to 80% remission rate. The fact that surgical treatment of PPGLs restores insulin sensitivity and secretion at greater extent compared to alpha and beta blockade, implies the existence of further, non-adrenergic mechanisms, possibly involving other hormonal co-secretion by these tumors. DM management in PPGLs is scarcely studied. The efficacy and safety of newer anti-diabetic medications, such as glucagon-like peptide 1 receptor agonists and sodium glucose cotransporter 2 inhibitors (SGLT2is), as well as potential disease-modifying roles of metformin and SGLT2is warrant further investigation in future studies.

Targeting adrenergic receptors to mitigate invariant natural killer T cells-induced acute liver injury

Invariant Natural Killer T (iNKT) cell activation by α-galactosylceramide (αGC) potentiates cytotoxic immune responses against tumors. However, αGC-induced liver injury is a limiting factor for iNKT-based immunotherapy. Although adrenergic receptor stimulation is an important immunosuppressive signal that curbs tissue damage induced by inflammation, its effect on the antitumor activity of invariant Natural Killer T (iNKT) cells remains unclear. We use mouse models and pharmacological tools to show that the stimulation of the sympathetic nervous system (SNS) inhibits αGC-induced liver injury without impairing iNKT cells' antitumoral functions. Mechanistically, SNS stimulation prevents the collateral effect of TNF-α production by iNKT cells and neutrophil accumulation in hepatic parenchyma. Our results suggest that the modulation of the adrenergic signaling can be a complementary approach to αGC-based immunotherapy to mitigate iNKT-induced liver injury without compromising its antitumoral activity.

Abstract P2027: Chronic β-Adrenergic Receptor Stimulation Exacerbates Left Ventricular Dilation And Myocardial Cell Death In Rgs2 Knockout Mice

Sustained sympathoexciation and increased circulating catecholamine level are hallmarks of congestive heart failure. Elevated catecholamine level promotes a sustained β -adrenergic receptor (βAR) stimulation in the myocardium, altering the balance between cell death and survival via intracellular signaling downstream of G s - and G i/o -class G proteins. Previously, we and others reported that moderation of Gα i activity by regulators of G protein signaling (RGS) 2 and 5 separately is key to maintaining normal ventricular rhythm. Here, using single isogenic wild type (WT), Rgs2 -/- , Rgs5 -/- , and Rgs2/5 double knockout (dbKO) adult male mice with or without systemic isoproterenol infusion, we determined whether a compensatory relationship between RGS2 and RGS5 is cardioprotective and promotes myocardial cell survival during chronic sympathoexcitation. We found that basal heart weight-to-tibia-length (HW/TL) ratio of both Rgs2 and dbKO mice was elevated relative to WT control. Echocardiography revealed left ventricular dilation in all three KO genotypes, as evidenced by increased left ventricular internal diameter and volume. Both Rgs2 -/- and Rgs5-/- mice displayed reduced ejection fraction and fractional shortening. To explore the mechanism mediating the LV dilation, we challenged the mice with chronic βAR stimulation by systemic isoproterenol infusion (ISO, 30 mg/kg/day) for 3 or 14 days via subcutaneous osmotic mini-pumps. ISO infusion substantially increased HW/TL ratio in WT mice after day 3, while HW/TL ratio in Rgs2 -/- and dbKO mice was increased with exacerbated LV dilation. After 14-day ISO infusion, only dbKO mice displayed increased lung weight/TL ratio, indicating a congestive heart failure. Additionally, myocardial tissue from saline treated dbKO mice had a larger number of TUNEL + cells that was further increased by ISO infusion, with extensive interstitial fibrosis as visualized with Masson trichrome staining, and increased expression of heart failure biomarkers Mybpc3 and Tnni3 . Taken together, we conclude that the loss of R gs2, more-so than Rgs5, predisposes to myocardial cell death and rapid progression to dilated cardiomyopathy and heart failure during sustained sympathoexciation and β-adrenergic stimulation.

Regulation of the Ca2+ Channel CaV1.2 Supports Spatial Memory and Its Flexibility and LTD.

Widespread release of norepinephrine (NE) throughout the forebrain fosters learning and memory via adrenergic receptor (AR) signaling, but the molecular mechanisms are largely unknown. The β2 AR and its downstream effectors, the trimeric stimulatory Gs-protein, adenylyl cyclase (AC), and the cAMP-dependent protein kinase A (PKA), form a unique signaling complex with the L-type Ca2+ channel (LTCC) CaV1.2. Phosphorylation of CaV1.2 by PKA on Ser1928 is required for the upregulation of Ca2+ influx on β2 AR stimulation and long-term potentiation induced by prolonged theta-tetanus (PTT-LTP) but not LTP induced by two 1-s-long 100-Hz tetani. However, the function of Ser1928 phosphorylation in vivo is unknown. Here, we show that S1928A knock-in (KI) mice of both sexes, which lack PTT-LTP, express deficiencies during initial consolidation of spatial memory. Especially striking is the effect of this mutation on cognitive flexibility as tested by reversal learning. Mechanistically, long-term depression (LTD) has been implicated in reversal learning. It is abrogated in male and female S1928A knock-in mice and by β2 AR antagonists and peptides that displace β2 AR from CaV1.2. This work identifies CaV1.2 as a critical molecular locus that regulates synaptic plasticity, spatial memory and its reversal, and LTD.SIGNIFICANCE STATEMENT We show that phosphorylation of the Ca2+ channel CaV1.2 on Ser1928 is important for consolidation of spatial memory and especially its reversal, and long-term depression (LTD). Identification of Ser1928 as critical for LTD and reversal learning supports the model that LTD underlies flexibility of reference memory.

CAMPing up cancer immunotherapy.

Adrenergic receptor stimulation improves cancer immunotherapy in a range of immune-competent tumor models.

Functional Involvement of ADRA1D in Cutaneous Melanoma Progression and Angiogenesis.

Cutaneous melanoma is a highly aggressive and malignant skin cancer, and its high recurrence rate and drug resistance increase the difficulty of treating advanced-stage patients. Studies have revealed that treatment via stimulation of alpha-1 adrenergic receptor (ADRA1) subtypes inhibits melanoma growth in mice. However, the associations between alpha-1D adrenergic receptor (ADRA1D) and cutaneous melanoma are poorly understood. Tissue specimens from 16 pairs of patients with a pigmented nevus and cutaneous melanoma were analyzed for ADRA1D expression using immunohistochemical staining. Western blotting and RT-qPCR were carried out in order to detect ADRA1D expression levels in melanoma cells and human epidermal melanocytes (HEMs), hypoxia-inducible factor-1α (HIF-1α), and vascular endothelial growth factor (VEGF) levels in HUVECS. A375 cells were transfected with a lentivirus overexpressing ADRA1D. Wound-healing, Transwell, and cell proliferation assays were utilized to identify the ADRA1D effect on the migration, invasion, and proliferation of the two groups of A375 cells in vitro. In order to evaluate the function of ADRA1D in vivo, a melanoma xenograft model was developed in immunodeficient mice. ADRA1D was low expressed in cutaneous melanoma tissues. Overexpression of ADRA1D inhibited the tubulation and migration of HUVECs in vitro. Overexpression of ADRA1D significantly decreased the HIF-1α and VEGF expression. Overexpression of ADRA1D inhibited the invasion and proliferation of A375 melanoma cells in vitro and reduced its angiogenesis in vivo. ADRA1D inhibits cutaneous melanoma growth and angiogenesis. It attenuates melanoma cell proliferation and invasion. Meanwhile, its anti-angiogenic effect is achieved by negatively regulating the HIF-1α/VEGF axis in melanoma tissue, thereby attenuating the growth of cutaneous melanoma and reducing the potential of metastasis.

ROK and RSK2-kinase pathways differ between senescent human renal and mesenteric arteries.

Small arteries from different organs vary with regard to the mechanisms that regulate vasoconstriction. This study investigated the impact of advanced age on the regulation of vasoconstriction in isolated human small arteries from kidney cortex and periintestinal mesenteric tissue. Renal and mesenteric tissues were obtained from patients (mean age 71 ± 9 years) undergoing elective surgery. Furthermore, intrarenal and mesenteric arteries from young and aged mice were studied. Arteries were investigated by small vessel myography and western blot. Human intrarenal arteries (h-RA) showed higher stretch-induced tone and higher reactivity to α 1 adrenergic receptor stimulation than human mesenteric arteries (h-MA). Rho-kinase (ROK) inhibition resulted in a greater decrease in Ca 2+ and depolarization-induced tone in h-RA than in h-MA. Basal and α 1 adrenergic receptor stimulation-induced phosphorylation of the regulatory light chain of myosin (MLC 20 ) was higher in h-RA than in h-MA. This was associated with higher ROK-dependent phosphorylation of the regulatory subunit of myosin light-chain-phosphatase (MLCP), MYPT1-T853. In h-RA phosphorylation of ribosomal S6-kinase II (RSK2-S227) was significantly higher than in h-MA. Stretch-induced tone and RSK2 phosphorylation was also higher in interlobar arteries (m-IAs) from aged mice than in respective vessels from young mice and in murine mesenteric arteries (m-MA) from both age groups. Vasoconstriction in human intrarenal arteries shows a greater ROK-dependence than in mesenteric arteries. Activation of RSK2 may contribute to intrarenal artery tone dysregulation associated with aging. Compared with h-RA, h-MA undergo age-related remodeling leading to a reduction of the contractile response to α 1 adrenergic stimulation.

β3 adrenergic receptor activation modulates connexin 43 activity to relax human myometrium

Preterm labor, delivery prior to 37 completed weeks of gestation, is the leading cause of infant morbidity and mortality. β3 adrenergic receptor protein expression is increased in the myometrium during pregnancy, and the agonist, mirabegron, relaxes the myometrium making the β3 adrenergic receptor a potential therapeutic target in PTL. β3 adrenergic receptor has been shown to activate the tyrosine kinase, Src, which can down regulate connexin 43, a contractile associated protein which promotes the formation of gap junctions that create an electrical syncytium. We hypothesize that mirabegron downregulates connexin 43, imparting quiescence effects on the myometrium. Employing contractile studies, we demonstrate that Src is involved in the mirabegron-induced relaxation of contracting pregnant human myometrial tissue strips. Western blot analysis demonstrates that Src kinase expression is decreased in both preterm and term laboring myometrial tissue. Imaging revealed that mirabegron stimulation of the β3 adrenergic receptor phosphorylates tyrosine at position Y265 on connexin 43 in pregnant human uterine myocytes. Western blot analysis and immunofluorescent imaging indicate that mirabegron decreases the expression of connexin 43 and mediates relaxation over a 24-h exposure period, suggesting that mirabegron has long lasting quiescent effects on the human myometrium. The relationship between the β3 adrenergic receptor and down regulation of the contractile associated protein connexin 43 through activation of Src kinase suggests that mirabegron may be useful in combination tocolysis.

Examination of the role of adrenergic receptor stimulation in the sensitization of neuroinflammatory-based depressive-like behavior in isolated Guinea pig pups

Early-life attachment disruption appears to sensitize neuroinflammatory signaling to increase later vulnerability for stress-related mental disorders, including depression. How stress initiates this process is unknown, but studies with adult rats and mice suggest sympathetic nervous system activation and/or cortisol elevations during the early stress are key. Guinea pig pups isolated from their mothers exhibit an initial active behavioral phase characterized by anxiety-like vocalizing. This is followed by inflammatory-dependent depressive-like behavior and fever that sensitize on repeated isolation. Using strategies that have been successful in adult studies, we assessed whether sympathetic nervous system activity and cortisol contributed to the sensitization process in guinea pig pups. In Experiment 1, the adrenergic agonist ephedrine (3 or 10 mg/kg), either alone or with cortisol (2.5 mg/kg), did not increase depressive-like behavior or fever during initial isolation the following day as might have been expected to if this stimulation was sufficient to account for the sensitization process. In Experiment 2, both depressive-like behavior and fever sensitized with repeated isolation, but beta-adrenergic receptor blockade with propranolol (10 or 20 mg/kg) did not affect either of these responses or their sensitization. The high dose of propranolol did, however, reduce vocalizing. These results suggest sympathetic nervous system activation is neither necessary nor sufficient to induce the presumptive neuroinflammatory signaling underlying sensitization of depressive-like behavioral or febrile responses in developing guinea pigs. Thus, processes mediating sensitization of neuroinflammatory-based depressive-like behavior following early-life attachment disruption in this model appear to differ from those previously found to underlie neuroinflammatory priming in adults.

β3 adrenergic agonism: A novel pathway which improves right ventricular-pulmonary arterial hemodynamics in pulmonary arterial hypertension.

Efficacy of therapies that target the downstream nitric oxide (NO) pathway in pulmonary arterial hypertension (PAH) depends on the bioavailability of NO. Reduced NO level in PAH is secondary to "uncoupling" of endothelial nitric oxide synthase (eNOS). Stimulation of β3 adrenergic receptors (β3 ARs) may lead to the recoupling of NOS and therefore be beneficial in PAH. We aimed to examine the efficacy of β3 AR agonism as a novel pathway in experimental PAH. In hypoxia (5 weeks) and Sugen hypoxia (hypoxia for 5 weeks + SU5416 injection) models of PAH, we examined the effects of the selective β3 AR agonist CL316243. We measured echocardiographic indices and invasive right ventricular (RV)-pulmonary arterial (PA) hemodynamics and compared CL316243 with riociguat and sildenafil. We assessed treatment effects on RV-PA remodeling, oxidative stress, and eNOS glutathionylation, an oxidative modification that uncouples eNOS. Compared with normoxic mice, RV systolic pressure was increased in the control hypoxic mice (p < 0.0001) and Sugen hypoxic mice (p < 0.0001). CL316243 reduced RV systolic pressure, to a similar degree to riociguat and sildenafil, in both hypoxia (p < 0.0001) and Sugen hypoxia models (p < 0.03). CL316243 reversed pulmonary vascular remodeling, decreased RV afterload, improved RV-PA coupling efficiency and reduced RV stiffness, hypertrophy, and fibrosis. Although all treatments decreased oxidative stress, CL316243 significantly reduced eNOS glutathionylation. β3 AR stimulation improved RV hemodynamics and led to beneficial RV-PA remodeling in experimental models of PAH. β3 AR agonists may be effective therapies in PAH.

PS-C20-5: WARM IV INFUSION IN HYPERTENSIVE URGENCY

Background: Hypertensive Urgency is defined as marked elevation in systemic blood pressure without any evidence of end organ damage. At present, the condition is managed with intravenous (IV) antihypertensives, of which most common is Sodium Nitroprusside. Aim: In this abstract we explore the possibility of slow IV infusion of warm (37–38oC) Normal Saline along with IV antihypertensives for a better and faster management of Hypertensive Urgency. Content: The slow IV will gradually increase the core body temperature of the patient while preventing fluid overload. Homeostatic regulation of Systemic Blood Pressure is maintained by an intricate network of correlated mechanisms, most of which are temperature dependent. The raised body temperature will be useful to control the Blood Pressure through the following mechanisms - Cardiac Output: reduces as core body temperature increases. Baroreflex: decreased post-synaptic adrenergic vasoconstrictor responses. Chemoreceptors: vascular responsiveness to adrenergic receptor stimulation reduces at higher temperatures. RAAS: Kosunen et al recorded reduced Systolic and Diastolic Blood Pressures at raised body temperatures despite increased levels of Angiotensin II &amp; Aldosterone. Endothelin: Serum concentration of Endothelin-I reduces at higher temperatures. Sweat: Thermal stimulation of sweat gland will help excretion of both salt and water, thus maintaining the sodium balance. VEGF: VEGF-A, a potent vasodilator, is increased during elevated body temperature. However, apart from Blood Pressure, a change in core body temperature causes change in many other parameters as well, which must be considered during this discussion. Coagulation profile - Valeri et al noted no change in in-vivo coagulation states till 100oF Effect on other visceral organs - Internal visceral organs like Liver, Kidneys and Brain were not affected till 100oF Infection Control - Core body temperature close to 100oF has also been found to have a protective role against invasive fungal infections in the ICU Discussion: Though the effects of various antihypertensive drugs to raised body temperatures need to be tested, the above points prove that introducing a protocol of warm IV saline Infusion in patients of Hypertensive Urgency may be extremely beneficial, and also prevent clinical inertia.

1261: LIBERATION FROM PROLONGED CATECHOLAMINE VASOPRESSOR EXPOSURE WITH 72-HOUR ANGIOTENSIN II INFUSION

Introduction: Angiotensin II produces vasoconstriction independent of adrenergic receptors and has been used in refractory shock. We report 2 patients in the recovery phase of shock that were successfully separated from prolonged exposure to catecholamines using 72-hours of angiotensin II infusion. Description: Case 1. A 46-year-old man with aortic valve dehiscence and recurrent endocarditis underwent redo mechanical aortic and mitral valve replacements. While recovering from multiple postoperative complications, he persistently required norepinephrine 0.06 mcg/kg/min, vasopressin 0.04 unit/min, droxidopa 300 mg q4h, and midodrine 15 mg q6h to maintain MAP > 55 mmHg for several weeks. Angiotensin II was trialed at 10 ng/kg/min and within 15 minutes the MAP was 86 mmHg and norepinephrine discontinued, with vasopressin stopped an hour later. Droxidopa and midodrine were also stopped, and over the next 72 hours angiotensin II was gradually tapered off in increments of 1-2 ng/kg/min every 6-12 hours. After a long hospital stay and eventual reintubation, the family decided to withdraw cares and the patient expired. Case 2. A 52-year-old man was admitted with urinary sepsis. After 4 weeks of complex treatment, he was recovering but persistently required norepinephrine 0.08 mcg/kg/min, vasopressin 0.04 unit/min, and midodrine 15 mg q8h to maintain MAP > 60 mmHg for 2 weeks. Angiotensin II was trialed at 20 ng/kg/min and within 30 minutes the MAP was 101 mmHg and norepinephrine discontinued, with vasopressin discontinued within 12 hours. Over the next 72 hours, midodrine was discontinued and angiotensin II was gradually tapered off. After an additional 8 weeks in the hospital, the patient discharged back to a skill nursing facility. Discussion: Prolonged stimulation of adrenergic receptors may lead to tachyphylaxis to catecholamines, believed to be due to adrenoreceptor desensitization and internalization. In such scenarios, alternative mechanisms of vasoconstriction may be necessary to achieve MAP targets. Angiotensin II engages the angiotensin type I receptor for venous and arterial constriction. We suspect in these two cases, augmenting MAP through the renin-angiotensin pathway provided a holiday from exogenous catecholamines and an opportunity for adrenoreceptors to externalize and re-sensitize.

Suppression of estrogen receptor beta classical genomic activity enhances systemic and adipose-specific response to chronic beta-3 adrenergic receptor (β3AR) stimulation.

White adipose tissue (WAT) dysfunction independently predicts cardiometabolic disease, yet there is a lack of effective adipocyte-targeting therapeutics. B3AR agonists enhance adipocyte mitochondrial function and hold potential in this regard. Based on enhanced sensitivity to B3AR-mediated browning in estrogen receptor (ER)alpha-null mice, we hypothesized that ERβ may enhance the WAT response to the B3AR ligand, CL316,243 (CL). Methods: Male and female wild-type (WT) and ERβ DNA binding domain knock-out (ERβDBDKO) mice fed high-fat diet (HFD) to induce obesity were administered CL (1 mg/kg) daily for 2 weeks. Systemic physiological assessments of body composition (EchoMRI), bioenergetics (metabolic chambers), adipocyte mitochondrial respiration (oroboros) and glucose tolerance were performed, alongside perigonadal (PGAT), subcutaneous (SQAT) and brown adipose tissue (BAT) protein expression assessment (Western blot). Mechanisms were tested in vitro using primary adipocytes isolated from WT mice, and from Esr2-floxed mice in which ERβ was knocked down. Statistical analyses were performed using 2 × 2 analysis of variance (ANOVA) for main effects of genotype (G) and treatment (T), as well as GxT interactions; t-tests were used to determine differences between in vitro treatment conditions (SPSS V24). Results: There were no genotype differences in HFD-induced obesity or systemic rescue effects of CL, yet ERβDBDKO females were more sensitive to CL-induced increases in energy expenditure and WAT UCP1 induction (GxT, p < 0.05), which coincided with greater WAT B3AR protein content among the KO (G, p < 0.05). Among males, who were more insulin resistant to begin with (no genotype differences before treatment), tended to be more sensitive to CL-mediated reduction in insulin resistance. With sexes combined, basal WAT mitochondrial respiration trended toward being lower in the ERβDBDKO mice, but this was completely rescued by CL (p < 0.05). Confirming prior work, CL increased adipose tissue ERβ protein (T, p < 0.05, all), an effect that was enhanced in WAT and BAT the female KO (GxT, p < 0.01). In vitro experiments indicated that an inhibitor of ERβ genomic function (PHTPP) synergized with CL to further increase UCP1 mRNA (p = 0.043), whereas full ERβ protein was required for UCP1 expression (p = 0.042). Conclusion: Full ERβ activity appears requisite and stimulatory for UCP1 expression via a mechanism involving non-classical ERβ signaling. This novel discovery about the role of ERβ in adipocyte metabolism may have important clinical applications.

Novel Smooth Muscle Ca2+-Signaling Nanodomains in Blood Pressure Regulation.

Ca2+ signals in smooth muscle cells (SMCs) contribute to vascular resistance and control blood pressure. Increased vascular resistance in hypertension has been attributed to impaired SMC Ca2+ signaling mechanisms. In this regard, transient receptor potential vanilloid 4 (TRPV4SMC) ion channels are a crucial Ca2+ entry pathway in SMCs. However, their role in blood pressure regulation has not been identified. We used SMC-specific TRPV4-/- (TRPV4SMC-/-) mice to assess the role of TRPV4SMC channels in blood pressure regulation. We determined the contribution of TRPV4SMC channels to the constrictor effect of α1 adrenergic receptor (α1AR) stimulation and elevated intraluminal pressure: 2 main physiologic stimuli that constrict resistance-sized arteries. The contribution of spatially separated TRPV4SMC channel subpopulations to elevated blood pressure in hypertension was evaluated in angiotensin II-infused mice and patients with hypertension. We provide first evidence that TRPV4SMC channel activity elevates resting blood pressure in normal mice. α1AR stimulation activated TRPV4SMC channels through PKCα (protein kinase Cα) signaling, which contributed significantly to vasoconstriction and blood pressure elevation. Intraluminal pressure-induced TRPV4SMC channel activity opposed vasoconstriction through activation of Ca2+-sensitive K+ (BK) channels, indicating functionally opposite pools of TRPV4SMC channels. Superresolution imaging of SMCs revealed spatially separated α1AR:TRPV4 and TRPV4:BK nanodomains in SMCs. These data suggest that spatially separated α1AR-TRPV4SMC and intraluminal pressure-TRPV4SMC-BK channel signaling have opposite effects on blood pressure, with α1AR-TRPV4SMC signaling dominating under resting conditions. Furthermore, in patients with hypertension and a mouse model of hypertension, constrictor α1AR-PKCα-TRPV4 signaling was upregulated, whereas dilator pressure-TRPV4-BK channel signaling was disrupted, thereby increasing vasoconstriction and elevating blood pressure. Our data identify novel smooth muscle Ca2+-signaling nanodomains that regulate blood pressure and demonstrate their impairment in hypertension.

Urothelium removal does not impact mucosal activity in response to muscarinic or adrenergic receptor stimulation

ABSTRACT The inner lining of the urinary bladder (urothelium and lamina propria, or bladder mucosa) has an important role as a tissue barrier between stored urine and the underlying smooth muscle, as well as in the modulation and regulation of bladder contractility. However, the individual influence of the apical urothelial layer on the contractile activity of this tissue is uncertain. The aim of this experiment was to identify the contractile activity of the lamina propria after removal of the urothelium. Several methods were used to mechanically disrupt the urothelium, including dabbing the tissue with a paper towel, longitudinal swipes with a cotton bud, or a longitudinal scrape with the edge of a scalpel. Hematoxylin-eosin staining was utilized to determine the level of removal of the apical urothelial cells. Spontaneous contractile activity was measured in organ baths, and responses to the agonists carbachol and isoprenaline were obtained. Three longitudinal swipes with a cotton bud was found to be the optimal method to remove the majority of the urothelium without damaging the lamina propria. Upon removal of the urothelium, the spontaneous activity of the tissue was unaltered. Similarly, responses to carbachol (1 µM) and isoprenaline (1 µM) were not affected after removal of the urothelium. The urothelium can be effectively removed without damaging the lamina propria. This apical tissue layer is not responsible for mediating the increases to spontaneous phasic activity or tonic contractions of the bladder mucosa (urothelium with lamina propria) when muscarinic or adrenergic receptors are stimulated. This research presents the lamina propria as the important cell layer mediating the overall contractile activity of the bladder wall.