ATP-dependent Potassium Channels Research Articles

Purinergic inhibitory regulation of esophageal smooth muscle is mediated by P2Y receptors and ATP-dependent potassium channels in rats

Purines such as ATP are regulatory transmitters in motility of the gastrointestinal tract. The aims of this study were to propose functional roles of purinergic regulation of esophageal motility. An isolated segment of the rat esophagus was placed in an organ bath, and mechanical responses were recorded using a force transducer. Exogenous application of ATP (10–100 μM) evoked relaxation of the esophageal smooth muscle in a longitudinal direction under the condition of carbachol (1 μM) -induced precontraction. Pretreatment with a non-selective P2 receptor antagonist, suramin (500 μM), and a P2Y receptor antagonist, cibacron blue F3GA (200 μM), inhibited the ATP (100 μM) -induced relaxation, but a P2X receptor antagonist, pyridoxal phosphate-6-azophenyl-2,4-disulfonic acid (50 μM), did not affect it. A blocker of ATP-dependent potassium channels (KATP channels), glibenclamide (200 μM), inhibited the ATP-induced relaxation and application of an opener of KATP channels, nicorandil (50 μM), produced relaxation. The findings suggest that ATP is involved in inhibitory regulation of the longitudinal smooth muscle in the muscularis mucosae of the rat esophagus via activation of P2Y receptors and then opening of KATP channels.

Exploring the Pathophysiology of ATP-Dependent Potassium Channels in Insulin Resistance.

Ionic channels are present in eucaryotic plasma and intracellular membranes. They coordinate and control several functions. Potassium channels belong to the most diverse family of ionic channels that includes ATP-dependent potassium (KATP) channels in the potassium rectifier channel subfamily. These channels were initially described in heart muscle and then in other tissues such as pancreatic, skeletal muscle, brain, and vascular and non-vascular smooth muscle tissues. In pancreatic beta cells, KATP channels are primarily responsible for maintaining the membrane potential and for depolarization-mediated insulin release, and their decreased density and activity may be related to insulin resistance. KATP channels' relationship with insulin resistance is beginning to be explored in extra-pancreatic beta tissues like the skeletal muscle, where KATP channels are involved in insulin-dependent glucose recapture and their activation may lead to insulin resistance. In adipose tissues, KATP channels containing Kir6.2 protein subunits could be related to the increase in free fatty acids and insulin resistance; therefore, pathological processes that promote prolonged adipocyte KATP channel inhibition might lead to obesity due to insulin resistance. In the central nervous system, KATP channel activation can regulate peripheric glycemia and lead to brain insulin resistance, an early peripheral alteration that can lead to the development of pathologies such as obesity and Type 2 Diabetes Mellitus (T2DM). In this review, we aim to discuss the characteristics of KATP channels, their relationship with clinical disorders, and their mechanisms and potential associations with peripheral and central insulin resistance.

Mitochondrial Calcium Uniporter (MCU) is Involved in an Ischemic Postconditioning Effect Against Ischemic Reperfusion Brain Injury in Mice

The phenomenon of ischemic postconditioning (PostC) is known to be neuroprotective against ischemic reperfusion (I/R) injury. One of the key processes in PostC is the opening of the mitochondrial ATP-dependent potassium (mito-KATP) channel and depolarization of the mitochondrial membrane, triggering the release of calcium ions from mitochondria through low-conductance opening of the mitochondrial permeability transition pore. Mitochondrial calcium uniporter (MCU) is known as a highly sensitive transporter for the uptake of Ca2+ present on the inner mitochondrial membrane. The MCU has attracted attention as a new target for treatment in diseases, such as neurodegenerative diseases, cancer, and ischemic stroke. We considered that the MCU may be involved in PostC and trigger its mechanisms. This research used the whole-cell patch-clamp technique on hippocampal CA1 pyramidal cells from C57BL mice and measured changes in spontaneous excitatory post-synaptic currents (sEPSCs), intracellular Ca2+ concentration, mitochondrial membrane potential, and N-methyl-d-aspartate receptor (NMDAR) currents under inhibition of MCU by ruthenium red 265 (Ru265) in PostC. Inhibition of MCU increased the occurrence of sEPSCs (p = 0.014), NMDAR currents (p < 0.001), intracellular Ca2+ concentration (p < 0.001), and dead cells (p < 0.001) significantly after reperfusion, reflecting removal of the neuroprotective effects in PostC. Moreover, mitochondrial depolarization in PostC with Ru265 was weakened, compared to PostC (p = 0.004). These results suggest that MCU affects mitochondrial depolarization in PostC to suppress NMDAR over-activation and prevent elevation of intracellular Ca2+ concentrations against I/R injury.Graphical

Errata: Effect of Thimerosal on Arrhythmia Induced by Coronary Ligation: The Involvement of ATP-dependent Potassium Channels.

Several errors (shown with underlines) in the following list appeared in the article "Effect of Thimerosal on Arrhythmia Induced by Coronary Ligation: The Involvement of ATP-dependent Potassium Channels" by Ömer Bozdogan, Ersöz Gonca, Melih Nebigil, Eylem Suveren Tiryaki (Vol. 46 No.4, 711-721, 2005).

Molecular Mechanisms of Neuroprotection after the Intermittent Exposures of Hypercapnic Hypoxia.

The review introduces the stages of formation and experimental confirmation of the hypothesis regarding the mutual potentiation of neuroprotective effects of hypoxia and hypercapnia during their combined influence (hypercapnic hypoxia). The main focus is on the mechanisms and signaling pathways involved in the formation of ischemic tolerance in the brain during intermittent hypercapnic hypoxia. Importantly, the combined effect of hypoxia and hypercapnia exerts a more pronounced neuroprotective effect compared to their separate application. Some signaling systems are associated with the predominance of the hypoxic stimulus (HIF-1α, A1 receptors), while others (NF-κB, antioxidant activity, inhibition of apoptosis, maintenance of selective blood-brain barrier permeability) are mainly modulated by hypercapnia. Most of the molecular and cellular mechanisms involved in the formation of brain tolerance to ischemia are due to the contribution of both excess carbon dioxide and oxygen deficiency (ATP-dependent potassium channels, chaperones, endoplasmic reticulum stress, mitochondrial metabolism reprogramming). Overall, experimental studies indicate the dominance of hypercapnia in the neuroprotective effect of its combined action with hypoxia. Recent clinical studies have demonstrated the effectiveness of hypercapnic-hypoxic training in the treatment of childhood cerebral palsy and diabetic polyneuropathy in children. Combining hypercapnic hypoxia with pharmacological modulators of neuro/cardio/cytoprotection signaling pathways is likely to be promising for translating experimental research into clinical medicine.

Development of a gastroprotector from Algrizea minor essential oil complexed with β-Cyclodextrin

Algrizea minor, a member of the Myrtaceae family, is found in the Cerrado and Caatinga biomes. Essential oils (EO) are highly volatile, prompting the need to minimize volatilization losses and enhance their therapeutic effects. Cyclodextrins, cyclic and inert oligosaccharides, have the capability to form inclusion complexes with various molecules. Gastritis, an inflammatory condition, manifests painful episodes that may involve gastric and duodenal peptic ulcers. This study aims to evaluate the pharmacological potential of Algrizea minor essential oil in both free and complexed forms with β-Cyclodextrin (β-CD). The inclusion complex was created by combining essential oil and β-CD in a 1:1 ratio based on the molecular weight of the major compound in the oil. Characterization was conducted using Fourier-Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Thermogravimetry (TG). Gastroprotective capacity, physical barrier, and pathways of gastroprotection were assessed. The essential oil distinguished itself with the presence of β-Pinene and α-Pinene. Characterization of the inclusion complex revealed features of both the EO and β-CD. Tests demonstrated the curative efficacy of both free and complexed oils, with effectiveness dependent on the dosage. Intense gastroprotective activity was observed, with 90.25% and 99% inhibition of gastric injury for the free and complexed oils, respectively. It was determined that the pharmacological mechanism of action involves the stimulation of sulfhydryl compound production, the expression of nitric oxide (NO) and ATP-dependent potassium channels. Cytokines and oxidative stress were measured, and their responses contradicted the gastroprotection analysis. The tests highlighted the curative efficiency of both free and complexed oils, showing intensified gastroprotective activity when Algrizea minor essential oil was complexed with β-Cyclodextrin.

Meta-Analysis of the Efficacy of Levosimendan in the Treatment of Severe Sepsis Complicated with Septic Cardiomyopathy.

Sepsis is a medical condition characterized by acute organ dysfunction and uncontrolled inflammation. Organ dysfunction in sepsis is the primary cause of mortality in patients with myocardial dysfunction. Levosimendan is a vasodilating and inotropic agent used in patients with acute heart failure and has resulted in decreased morbidity and mortality in these patients. Our main objective is to examine levosimendan's efficacy in treating severe sepsis complicated with septic cardiomyopathy. We systematically searched five databases, PubMed, Web of Science, Embase, Cochrane Library and BioMed Central, for articles and publications from their inception to 2023. Our study adopted the PICOS approach in identifying suitable publications during the systematic search. Inclusion criteria included randomized, controlled trials utilizing levosimendan in adult patients diagnosed with septic shock or severe sepsis. We excluded non-English publications and non-randomized controlled trials. The Newcastle-Ottawa scale (NOS) scale was used to assess the methodological quality, while the risk of bias was assessed through the Cochrane Risk of bias tool. All statistical analyses were performed using RevMan version 5.4. Eight studies met the eligibility criteria and were included in the analysis. There was a statistically significant positive effect on cardiac input in patients treated with levosimendan compared to those treated with dobutamine (p < 0.001). Similarly, there were positive effects on left ventricular ejection fraction (LVEF) (p < 0.001) and left ventricular stroke work index (LVSWI) (p < 0.001). We observed a significant reduction in mortality (p < 0.01) and serum levels of lactic acid (p < 0.01). Levosimendan is a calcium sensitizer associated with an influx of calcium ions and activation of ATP-dependent potassium channels that increases myocardial contractility contractions, enhances vasodilation and improves oxygen supply to the cells and tissues. Levosimendan is highly efficacious and safe in the management of sepsis and sepsis-induced cardiomyopathy.

SAT083 Comparing Grit, Anxiety, And Social Responsiveness In KCNJ11-NDM And Their Sibling Controls

Abstract Disclosure: J. Desai: None. L. Letourneau-Freiberg: None. M. Msall: None. M. Scott: None. R.N. Naylor: None. L. Philipson: None. S.W. Greeley: None. Background: Neonatal diabetes mellitus (NDM), diabetes with onset before 6-12 months of age, is most commonly caused from mutations in the ATP-dependent Potassium (KATP) channel genes: KCNJ11 (KCNJ11-NDM) or ABCC8. Because of brain expression of mutant KATP channels, a spectrum of neurodevelopmental difficulties have been described, such as developmental delay, epilepsy, and neonatal diabetes (DEND) syndrome, learning disorders, and Attention-deficit/hyperactivity disorder (ADHD). In order to understand more about specific challenges, we compared self- and parent/caregiver-reported grit, anxiety, and social responsiveness among participants with KCNJ11 mutations and their sibling controls. Methods: We recruited 12 families (12 KCNJ11-NDM participants and 10 sibling controls) through the University of Chicago Monogenic Diabetes Registry (www.monogenicdiabetes.org). Affected participants and sibling controls, and in some cases their parent/caregiver, completed the SCARED/SCAARED (anxiety), SRS-2 (social responsiveness) and Grit Scale (grit) surveys. Nonparametric analyses were performed using the Mann-Whitney U-test for group comparisons. Results: Individuals with KCNJ11-NDM had significantly worse social responsiveness scores compared to sibling controls in both Total Social Responsiveness and 4/5 subscales including Social Awareness, Cognition, Communication, and Restricted Interests and Repetitive Behavior (p&amp;lt;0.05), but no difference for Motivation. In terms of deficits in social interaction, 20% of KCNJ11-NDM participants had total SRS-2 T-scores in the mild range, 30% with scores in the moderate range, and 40% with scores in the severe range. 80% of control participants had total SRS-2 T-scores in normal range. Grit results were not significantly different between groups. Total anxiety scores and anxiety subscale scores were not significantly different between groups. Nevertheless, both participants with KCNJ11-NDM and sibling controls revealed greater levels of anxiety as a whole; 50% of KCNJ11-NDM participants (n=6) and 40% of unaffected controls (n=4) had mean total anxiety scores ≥ 25, indicating the possible presence of a clinical anxiety disorder. Conclusion: The prevalence of social interaction challenges was high among KCNJ11-NDM participants, highlighting the importance of early clinical assessment and support for such problems. Results of the SRS-2 Motivation subscale and Grit, which measure more intrinsic levels of personality, may suggest that individuals with KCNJ11-NDM exhibit intrinsic motivation and grit. Elevated overall anxiety levels in both KCNJ11-NDM participants and sibling controls suggest the need for early assessment and supportive interventions for families affected by KCNJ11-NDM. Presentation: Saturday, June 17, 2023

Uridine as a Regulator of Functional and Ultrastructural Changes in the Brain of Rats in a Model of 6-OHDA-Induced Parkinson's Disease.

Using a model of Parkinson's disease (PD) induced by the bilateral injection of neurotoxin 6-hydroxydopamine (6-OHDA) into rat brain substantia nigra (SN), we showed uridine to exert a protective effect associated with activation of the mitochondrial ATP-dependent potassium (mitoK-ATP) channel. Injection of 4 µg neurotoxin evoked a 70% decrease in the time the experimental animal spent on the rod in the RotaRod test, an increase in the amount of lipid peroxides in blood serum and cerebral-cortex mitochondria and the rate of reactive oxygen species formation, and a decrease in Ca2+ retention in mitochondria. Herewith, lymphocytes featured an increase in the activity of lactate dehydrogenase, a cytosolic enzyme of glycolysis, without changes in succinate-dehydrogenase activity. Structural changes occurring in the SN and striatum manifested themselves in the destruction of mitochondria, degeneration of neurons and synapses, and stratification of myelin sheaths in them. Subcutaneous injections of 30 µg/kg uridine for 22 days restored the neurotoxin-induced changes in these parameters to levels close to the control. 5-Hydroxydecanoate (5 mg/kg), a specific mitoK-ATP channel inhibitor, eliminated the beneficial effect of uridine for almost all characteristics tested, indicating the involvement of the mitoK-ATP channel in the protective effect of uridine. The mechanism of the protective effect of uridine and its therapeutic applications for the prevention and treatment of PD are discussed.

Molecular genetic diagnosis and treatment of congenital hyperinsulinism: results of observation of patients with variants in the genes &lt;i&gt;ABCC8&lt;/i&gt; and &lt;i&gt;KCNJ11&lt;/i&gt;

Congenital hyperinsulinism is a rare hereditary disease characterized by inadequate hypersecretion of insulin by pancreatic -cells, clinically manifested by persistent hypoglycemia, which poses a great threat to patient survival and a high risk of developing severe neurological complications.&#x0D; The article presents the results of clinical, hormonal and molecular genetic examination and treatment of 10 patients with congenital hyperinsulinism caused by mutations in the genes of ATP-dependent potassium channels (KCNJ11, ABCC8), hospitalized in Saint Petersburg State Pediatric Medical University clinic in 20102023. In all the studied patients, the disease manifested from the 1st to the 3rd day of life, and the median age of diagnosis of congenital hyperinsulinism in the study group was 1 month (min 14 days; max 3 years 9 months). In 8 out of 10 patients, a severe course of hypoglycemic syndrome was noted at the onset of the disease. According to the molecular genetic investigation results, 8 different mutations were identified: in the KCNJ11 (2/8) and ABCC8 (6/8) genes. Identical variants were found in two pairs of related patients. In children with mutations in the ABCC8 gene (n = 8), 2 variants with unknown clinical significance were identified, which were not previously described in allelic databases and scientific literature. According to the analysis of anamnestic and clinical and laboratory data, 80.0% of children, including patients with new, previously not described in the scientific literature, variants in the ABCC8 gene have a severe progressive course of congenital hyperinsulinism, requiring the appointment of insulinostatic therapy.

Ximenia americana L.: Chemical Characterization and Gastroprotective Effect

Ximenia americana L., popularly known in Brazil as “ameixa do-mato, ameixa-brava, and ameixa-do-sertão,” is widely used in folk medicine to treat several intestinal disorders. The present study assessed the potential mechanisms of action underlying the gastroprotective activity of the hydroethanolic extract of Ximenia americana L. (EHXA) stem bark. The acute toxicity of EHXA was estimated, and later, the gastroprotective effect in mice was assessed through acute models of gastric lesions induced by acidified or absolute ethanol and indomethacin, where the following mechanisms were pharmacologically analyzed: the involvement of prostaglandins (PG), histamine (H2) receptors, ATP-dependent potassium channels, sulfhydryl groups (SH), α2 adrenergic receptors, nitric oxide (NO), myeloperoxidase (MPO), gastric mucus production, and acetylcholine-mediated intestinal motility. Regarding toxicity, EHXA did not cause deaths or signs of toxicity (LD50 greater than or equal to 2000 mg/kg/p.o.). When the gastroprotective effect was assessed, EHXA (50, 100, and 200 mg/kg/p.o.) reduced the rate of lesions induced by acidified ethanol by 65.63; 53.66, and 58.02% in absolute ethanol at 88.91, 78.82, and 74.68%, respectively, when compared to the negative control group. In the indomethacin-induced gastric injury model, the reductions were 84.69, 55.99, 55.99, and 42.50%, respectively. The study revealed that EHXA might stimulate mucus production and reduce intestinal motility through SH groups, NO production, and activation of α2 adrenergic receptors. The results indicated that EHXA had significant gastroprotective activity in the evaluated models. However, further investigation is required to elucidate the cellular and molecular events underlying the action of EHXA components and to correlate them with the modulation of the signaling pathways, as demonstrated by the current pharmacological approach. Therefore, the results demonstrated in the present study, as well as previously reported findings, support the recommendation of using this species in traditional communities in Brazil.

Motor Dysfunction of Gastric Antral Smooth Muscle in Diabetic Rats: Contribution of ATP-Dependent Potassium Channels.

The goal of the current research was to further elucidate the role of adenosine triphosphate (ATP)-sensitive potassium (KATP) channels in the motility and contractility force of gastric smooth muscle of diabetic rats. Male Wistar rats (190-230 g) were grouped into control and streptozotocin (STZ)-induced diabetes (55 mg/kg) rats. Thirty days later, gastric muscle contractility was measured using a myograph and a force transducer of antral segments immersed in a tissue bath. Gastric emptying response was measured through feeding of standard pellet. Furthermore, the expression of KATP channel subunits in antral smooth muscle was determined by western blot technique. The amplitude of KCl-evoked twitch contractions of diabetic antral strips was about 25% more than control (P < 0.05). Application of minoxidil, a KATP channel opener, dose dependently decreased the force of twitch contractions in both normal and diabetic antral strips. Application of 10 μM glibenclamide, a KATP channel blocker, did not antagonize the minoxidil-induced relaxation of antral strips. Diabetic gastric emptying was faster than normal, although not significant. Despite the relaxant effect of minoxidil on gastric emptying rate in normal rats (P < 0.05), this effect was not observed in diabetic rats. Also, glibenclamide increased gastric emptying and antagonized minoxidil-induced relaxation in normal rats (P < 0.05). Furthermore, the expression of KATP Kir6.1 and SUR2B subunits was substantially reduced in antral smooth muscle in diabetic condition (P < 0.01). These results propose that KATP channels may contribute to the development of gastric motility disorders in diabetes.

Cytotoxic and genotoxic effects of nateglinide on human ovarian, prostate, and colon cancer cell lines

Objective: Nateglinide, an oral anti-diabetic medication used to treat type 2 diabetes, activates ATP-dependent potassium channels in pancreatic beta cells and induces insulin secretion. Numerous antidiabetic medicines, particularly metformin, are known to drastically reduce the viability of cancer cells. This study examined the effects of nateglinide on the DNA and viability of human ovarian (A2780), prostate (LNCaP), and colon (Caco-2) cancer cells. Materials and methods: Initially in the study, 1, 10, 100, and 1000 µM doses of nateglinide were administered for 24 hours to A2780, LNCaP, and Caco-2 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was used to measure cell viability. Using Graphpad Prism 8, the inhibitory logarithmic concentration values (LogIC50) of nateglinide in A2780, LNCaP, and Caco-2 cells were computed based on the results of the MTT experiment. These doses were applied to A2780, LNCaP, and Caco-2 cells for the Comet assay. The Bonferroni-corrected Mann–Whitney U test was used to compare groups, and a value of p&lt;0.05 was considered statistically significant. Results: In A2780 and LNCaP cell lines, only 1000 μM nateglinide concentration decreased cell viability (p&lt;0.05), whereas in Caco-2 cells, all concentrations except 1 μM reduced cell viability (p&lt;0.05). The Comet assay indicated that nateglinide produced DNA damage by increasing the tail lengths and tail moments of A2780, LNCaP, and Caco-2 cells (p&lt;0.05) and reducing the head diameters (p&lt;0.05). Conclusion: According to the findings of this study, nateglinide has cytotoxic effects on human ovarian, prostate and colon cancer cell lines and may possess anticancer properties.

Vasoplegic Syndrome after Cardiopulmonary Bypass in Cardiovascular Surgery: Pathophysiology and Management in Critical Care.

Vasoplegic syndrome (VS) is a common complication following cardiovascular surgery with cardiopulmonary bypass (CPB), and its incidence varies from 5 to 44%. It is defined as a distributive form of shock due to a significant drop in vascular resistance after CPB. Risk factors of VS include heart failure with low ejection fraction, renal failure, pre-operative use of angiotensin-converting enzyme inhibitors, prolonged aortic cross-clamp and left ventricular assist device surgery. The pathophysiology of VS after CPB is multi-factorial. Surgical trauma, exposure to the elements of the CPB circuit and ischemia-reperfusion promote a systemic inflammatory response with the release of cytokines (IL-1β, IL-6, IL-8, and TNF-α) with vasodilating properties, both direct and indirect through the expression of inducible nitric oxide (NO) synthase. The resulting increase in NO production fosters a decrease in vascular resistance and a reduced responsiveness to vasopressor agents. Further mechanisms of vasodilation include the lowering of plasma vasopressin, the desensitization of adrenergic receptors, and the activation of ATP-dependent potassium (KATP) channels. Patients developing VS experience more complications and have increased mortality. Management includes primarily fluid resuscitation and conventional vasopressors (catecholamines and vasopressin), while alternative vasopressors (angiotensin 2, methylene blue, hydroxocobalamin) and anti-inflammatory strategies (corticosteroids) may be used as a rescue therapy in deteriorating patients, albeit with insufficient evidence to provide any strong recommendation. In this review, we present an update of the pathophysiological mechanisms of vasoplegic syndrome complicating CPB and discuss available therapeutic options.

Fibroblast growth factor 10 ameliorates renal ischaemia-reperfusion injury by attenuating mitochondrial damage.

Ischaemia-reperfusion (I/R) injury is one of the leading causes of acute kidney injury (AKI). Its pathologic mechanism is quite complex, involving oxidative stress, inflammatory response, autophagy, and apoptosis. Fibroblast growth factor 10 (FGF10) and 5-hydroxydecanoate (5-HD) play essential roles in kidney injury. Rats were divided into four groups: (i) sham group, sham-operated animals with an unconstructed renal artery; (ii) I/R group, kidneys were subjected to 50 min of ischaemia followed by reperfusion for 2 days; (iii) I/R + FGF10 group, animals treated with 0.5mg/kg FGF10 (i.p.) 1h before ischaemia; and (iv) 5-HD group, animals treated with 5mg/kg 5-HD (i.m.) 30 min before FGF10 treatment. Renal injury, apoptosis damage, mitochondrial oxidative damage, mitochondrial membrane potential (MMP), and expression of the ATP-sensitive K+ (KATP) channel subunit Kir6.2 were evaluated. FGF10 treatment significantly alleviated I/R-induced elevation in the serum creatinine level and the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling-positive tubular cells in the kidney. In addition, FGF10 dramatically ameliorated renal mitochondrial-related damage, including reducing mitochondrial-dependent apoptosis, alleviating oxidative stress, maintaining the mitochondrial membrane potential, and opening the mitochondrial KATP channels. The protective effect of FGF10 was significantly compromised by the ATP-dependent potassium channel blocker 5-HD. Our data suggest that FGF10 offers effective protection against I/R and improves animal survival by attenuating mitochondrial damage.

Deletion of serine racemase reverses neuronal insulin signaling inhibition by amyloid-β oligomers.

Dysregulation of insulin signaling in the Alzheimer's disease (AD) brain has been extensively reported. Serine racemase (SR) modulates insulin secretion in pancreatic islets. This study aimed to examine whether SR regulates insulin synthesis and secretion in neurons, thereby modulating insulin signaling in the AD brain. Srr-knockout (Srr-/- ) mice generated with the CRISPR/Cas9 technique were used. Using immunofluorescence and fluorescence in situ hybridization, levels of insulin protein and insulin(ins2) mRNA were significantly increased in the hippocampal but not in hypothalamic sections of Srr-/- mice compared with WT mice. Real-time quantitative PCR revealed that ins2 mRNA from primary hippocampal neuronal cultures of Srr-/- mice was significantly increased compared with that from cultured neurons of WT mice. Notably, the secretion of proinsulin C-peptide was increased in Srr-/- neurons relative to WT neurons. By examining membrane fractional proteins with immunoblotting, Srr-/- neurons retained ATP-dependent potassium channels on plasmalemma and correspondingly contained higher levels of p-AMPK. After treatment with Aβ42, the phosphorylation levels of insulin receptor substrate at serine 616 636 (p-IRS1ser616,636 ) were significantly lower, whereas p-AKT308 and p-AKT473 were higher in Srr-/- neurons than in WT neurons, respectively. The phosphorylated form of c-Jun N-terminal kinase decreased in the cultured Srr-/- neurons relative to the WT neurons upon Aβ42 treatment. In contrast, phosphorylated protein kinase R remained at the same levels. Further, reactive oxygen species were reduced in cultured Srr-/- neurons under Aβ42 treatment relative to the WT neurons. Collectively, our study indicated that Srr deletion promoted insulin synthesis and secretion of proinsulin C-peptide, thereby reversing insulin resistance by Aβ42. This study suggests that targeting the neuronal SR may be utilized to enhance insulin signaling which is inhibited at the early stage of the AD brain.

Outcomes in patients with acute heart failure treated with levosimendan: the impact of right ventricular function

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Despite recent advances, acute heart failure poses a therapeutic challenge due to its high morbidity and mortality both in the short and long term. Particularly, right ventricle failure is associated with worst outcomes. Levosimendan has emerged as an option and its use is the object of ongoing investigation. Its mechanism of action relies both on troponin C calcium sensitization to improve contractility and ATP-dependent potassium channels activation of promoting vasodilation. These actions cause well-established effects on the function of the left ventricle and systemic circulation, but little is known of the role of the right ventricle. We aimed to compare the outcomes of patients who received levosimendan regarding the presence of right ventricular failure. Methods Single-center retrospective study, including all hospitalized adult patients that received levosimendan for acute heart failure from 2011 to 2020. Cardiac surgery patients were excluded. Right heart failure was assessed by echocardiography and categorized as normal or mildly, moderately, or severely reduced. Acute kidney injury was defined as a creatinine increase of ≥ 50% or ≥ 0.3 mg/dl from its baseline. Results A total of 52 patients were included for analysis. Their basal characteristics are described in table 1. All 3 patients (5.8%) that died during hospitalization showed right ventricular dysfunction. Acute kidney injury was more common in patients with right ventricular dysfunction (36.4% versus 10.5%, p = 0.04), as can be seen in figure 1. There were 9 cases of hypotension (17.3%), with no significant differences between groups. Conclusion In patients, hospitalized with acute heart failure who received levosimendan, right ventricle failure with associated with worst outcomes, particularly with acute kidney injury.

Effect of soya phosphatidylcholine and possible underlying mechanism on ischemia/reperfusion injury in isolated perfused rat heart: an experimental and computational study.

This study was designed to assess the effect of soya phosphatidylcholine (SPC) against ischemia/reperfusion (I/R) injury and the possible underlying mechanism using experimental and computational studies. I/R injury was induced by global ischemia for 30min followed by reperfusion for 120min. The perfusion of the SPC was performed for 10min before inducing global ischemia. In the mechanistic study, the involvement of specific cellular pathways was identified using various inhibitors such as ATP-dependent potassium channel (KATP) inhibitor (glibenclamide), protein kinase C (PKC) inhibitor (chelerythrine), non-selective nitric oxide synthase inhibitor (L-NAME), and endothelium remover (Triton X-100). The computational study of various ligands was performed on toll-like receptor 4 (TLR4) protein using AutoDock version 4.0. SPC (100 μM) significantly decreased the levels of cardiac damage markers and %infarction compared with the vehicle control (VC). Furthermore, cardiodynamics (indices of left ventricular contraction (dp/dtmax), indices of left ventricular relaxation (dp/dtmin), coronary flow, and antioxidant enzyme levels were significantly improved as compared with VC. This protective effect was attenuated by glibenclamide, chelerythrine, and Triton X-100, but it was not attenuated by L-NAME. The computational study showed a significant bonding affinity of SPC to the TLR4-MD2 complex. Thus, SPC reduced myocardial I/R injury in isolated perfused rat hearts, which might be governed by the KATP channel, PKC, endothelium response, and TLR4-MyD88 signaling pathway.

Effect of Soforaflavonozide and Narcissine Flavonoids on ATP-dependent Potassium Channels of Rat Cardiac Mitochondria in the Ischemia Model

In this study, <i>in vitro</i> and <i>in vivo</i> experiments, it was studied soforaflavonozide (SFL) isolated from <i>Alhagi canescens</i> (Regel) B. Keller & Shap (Fabaceae (Leguminosae)), and narcissine isolated from <i>Crocus sativus</i> L. belonging to Iridaceae family. It was studied the effect of narcissine isolated from the plant on ATP-dependent potassium channel (mitoK<SUB>ATP</SUB>-channel) activity in rat cardiac mitochondria. Animals of experimental group were divided into 4 groups: I control group (healthy), II experimental group (ischemia model), III experiment group (ischemia + narcissin), IV experimental group (ischemia + SFL). In rats with ischemia a 0.1 ml 0.1% solution of 100 mg/kg adrenaline was administered subcutaneously and peritoneally for 3 days in relative to body weight. The rats that underwent the ischemia model were given oral administration of 10 mg/kg of narcissine flavonoid to group III and 10 mg/kg of SFL flavonoid to group IV orally for 7 days. After that, in the experimental animals carried out electrocardiogram. Mitochondria from rat heart tissue were isolated by differential centrifugation. Cardiac mitoK<SUB>ATP</SUB>-channel activity in the presence of ATP in an incubation medium was studied at concentrations of 10–50 μM of SFL and narcissine. Concentrations of 50 μM of SFL and narcissus and 30 μM of diazoxide were also found to have an activating effect on the mitochondrial channel of the heart. In the adrenaline-induced ischemia model, it was found that narcissine and SFL flavonoids restored the mitochondrial conduction permeability of the rat heart.

Dose-dependent Spasmolytic, Bronchodilator, and Hypotensive Activities of Panicum miliaceum L.

Panicum miliaceum L. is a medicinally effective plant used in indigenous system of medicine for a variety of ailments. However, there is no comprehensive study explaining its effectiveness in gastrointestinal tract, respiratory, and cardiovascular system ailments. This study was designed to validate the pharmacological basis for the folkloric use of Panicum miliaceum L. in diarrhea, asthma, and hypertension. Panicum miliaceum extract was analyzed to detect the presence of bioactive compounds by HPLC. The isolated rabbit jejunum, trachea, and aorta were used for in vitro experiments using tissue bath assembly coupled with Power Lab data acquisition system to explore their relative effects. In-vivo experiments were performed for anti-diarrheal activity. HPLC analysis revealed the presence of gallic acid, butylated hydroxytoluene, catechin, and quercetin. Concentration dependent activities were observed by relaxing K+ (low) induced contractions having spasmolytic effect with EC50 = .358 ± .052, bronchodilator (EC50 = 2.483 ± .05793), and vasorelaxant (EC50 = .383 ± .063), probably due to the ATP dependent potassium channel activation. It was confirmed through pre-exposure of glibenclamide (specific ATP-dependent K+ channel blocker) having similarities with cromakalim. Pm.Cr revealed its antidiarrheal via in vivo experiments on rats. This study indicates that Panicum miliaceum has antidiarrheal, spasmolytic, bronchodilator, and vasorelaxant activities probably due to the ATP dependent K+ channel activation.