ATP Concentration Research Articles

A novel kinetic model to demonstrate the independent effects of ATP and ADP/Pi concentrations on sarcomere function.

Understanding muscle contraction mechanisms is a standing challenge, and one of the approaches has been to create models of the sarcomere-the basic contractile unit of striated muscle. While these models have been successful in elucidating many aspects of muscle contraction, they fall short in explaining the energetics of functional phenomena, such as rigor, and in particular, their dependence on the concentrations of the biomolecules involved in the cross-bridge cycle. Our hypothesis posits that the stochastic time delay between ATP adsorption and ADP/Pi release in the cross-bridge cycle necessitates a modeling approach where the rates of these two reaction steps are controlled by two independent parts of the total free energy change of the hydrolysis reaction. To test this hypothesis, we built a two-filament, stochastic-mechanical half-sarcomere model that separates the energetic roles of ATP and ADP/Pi in the cross-bridge cycle's free energy landscape. Our results clearly demonstrate that there is a nontrivial dependence of the cross-bridge cycle's kinetics on the independent concentrations of ATP, ADP, and Pi. The simplicity of the proposed model allows for analytical solutions of the more basic systems, which provide novel insight into the dominant mechanisms driving some of the experimentally observed contractile phenomena.

Ignored microbial-induced taste and odor in drinking water reservoirs: Novel insight into actinobacterial community structure, assembly, and odor-producing potential

The presence of actinobacteria in reservoirs can lead to taste and odor issues, posing potential risks to the safety of drinking water supply. However, the response of actinobacterial communities to environmental factors in drinking water reservoirs remains largely unexplored. To address this gap, this study investigated the community structure and metabolic characteristics of odor-producing actinobacteria in water reservoirs across northern and southern China. The findings revealed differences in the actinobacterial composition across the reservoirs, with Mycobacterium sp. and Candidatus Nanopelagicus being the most prevalent genera. Notably, water temperature, nutrient levels, and metal concentrations were associated with differences in actinobacterial communities, with stochastic processes playing a major role in shaping the community assembly. In addition, three strains of odor-producing actinobacteria were cultured in raw reservoir water, namely Streptomyces antibioticus LJH21, Streptomyces sp. ZEU13, and Streptomyces sp. PQK19, with peak ATP concentrations of 51 nmol/L, 66 nmol/L, and 70 nmol/L, respectively, indicating that odor-producing actinobacteria could remain metabolically active under poor nutrient pressure. Additionally, Streptomyces antibioticus LJH21 produced the highest concentration of geosmin at 24.4 ng/L. These findings enhance our understanding of regional variances and reproductive metabolic mechanisms of actinobacteria in drinking water reservoirs, providing a solid foundation for improving drinking water quality control, especially for taste and odor.

Potency and mechanism of p-glycoprotein chemosensitizers in rainbow trout (Oncorhynchus mykiss) hepatocytes.

The membrane efflux transporter P-glycoprotein (P-gp, [ABCB1, MDR1]) exports a wide range of xenobiotic compounds, resulting in a continuous first line of defense against toxicant accumulation at basal expression levels, and contributing to the multixenobiotic resistance (MXR) phenotype at elevated expression levels. Relatively little information exists on P-gp inhibition in fish by chemosensitizers, compounds which lower toxicity thresholds for harmful P-gp substrates in complex mixtures. The effects of four known mammalian chemosensitizers (cyclosporin A [CsA], quinidine, valspodar [PSC833], and verapamil) on the P-gp-mediated transport of rhodamine 123 (R123) and cortisol in primary cultures of rainbow trout (Oncorhynchus mykiss) hepatocytes were examined. Competitive accumulation assays using 25µM R123 or cortisol and varying concentrations of chemosensitizers (0-500µM) were used. CsA, quinidine, and verapamil inhibited R123 export (IC50 values ± SE: 132 ± 60, 83.3 ± 27.2, and 43.2 ± 13.6µM, respectively). CsA and valspodar inhibited cortisol export (IC50 values: 294 ± 106 and 92.2 ± 34.9µM, respectively). In an ATP depletion assay, hepatocytes incubated with all four chemosensitizers resulted in lower free ATP concentrations, suggesting that they act via competitive inhibition. Chemosensitizers that inhibit MXR transporters are an important class of environmental pollutant, and these results show that rainbow trout transporters are inhibited by similar chemosensitizers (and mostly at similar concentrations) as seen in mammals and other fish species.

Increased concentrations of P2X7R in oligodendrocyte derived extracellular vesicles of Multiple sclerosis patients

Activation of the purinergic receptor P2X7 (P2X7R) is believed to be deleterious in autoimmune diseases and it was hypothesized to play a role in the pathogenesis of MS. P2X7R is an ATP-gated non-selective cationic channel; its activation can be driven by high concentrations of ATP and leads to the generation of large, cytolytic conductance pores. P2X7R activation can also result in apoptosis as a consequence of the activation of the caspase cascade via P2X7R-dependent stimulation of the NLRP3 inflammasome. We measured P2X7R in oligodendrocyte derived extracellular vesicles (ODEVs) in MS patients and in healthy subjects.Sixty-eight MS patients (50 relapsing-remitting, RR-MS, 18 primary progressive, PP-MS) and 57 healthy controls (HC) were enrolled. ODEVs were enriched from serum by a double step immunoaffinity method using an anti OMGp (oligodendrocyte myelin glycoprotein) antibody. P2X7R concentration was measured in ODEVs lysates by ELISA.One–way Anova test showed that P2X7R in ODEVs is significantly higher in PP-MS (mean: 1742.89 pg/mL) compared both to RR-MS (mean: 1277.33 pg/mL) (p < 0.001) and HC (mean: 879.79 pg/mL) (p < 0.001). Comparison between RR-MS and HC was also statistically significant (p < 0.001). Pearson's correlations showed that P2RX7 in ODEVs was positively correlated with EDSS (p = 0.002, r = 0.38, 0.15–0.57 95% CI) and MSSS (p = 0.004, r = 0.34, 0.12–0.54 95% CI) scores, considering MS patients together (PP-MS + RR-MS) and with disease duration in PP-MS group (p = 0.02, r = 0.53, 0.09–0.80 95% CI).Results suggest that ODEVs-associated P2X7R levels could be a biomarker for MS.

Simultaneous recovery of short-chain fatty acids and diverse carbon sources using magnetic cationic surfactant-functionalized materials integrated with membrane contactor in dark syngas fermentation

Syngas fermentation utilizing acetogenic bacteria like Clostridium sp. provides a promising method for transforming CO and CO2-rich waste gases into valuable products such as short-chain fatty acids (SCFAs) and bio-alcohols, aiding in the reduction of greenhouse gas emissions and supporting carbon neutrality objectives. Magnetic nanoparticle-based coagulants, particularly Fe3O4@MIL-100(Fe)@TEOS@DTAB (FMT@DTAB), have recently attracted attention due to their efficient recovery and enhanced cell disruption capabilities enabled by cationic surfactant surface modifications. At a dosage of 60 g/L, FMT@DTAB has proven highly effective in achieving significant concentrations of acetic acid (7.06 g/L), butyric acid (6.27 g/L), ethanol (6.43 g/L), and butanol (5.24 g/L), along with notable harvesting efficiency (99.2 %) and intracellular ATP concentration (2.1 mM). Recent research on supported liquid membrane contactors highlights their cost-effective and environment-friendly properties, with an emphasis on minimal extractant usage. This study investigated the behavior of SCFAs using both virgin and supported liquid membrane contactors, focusing on factors such as organic extractant and membrane pore size. PVDF filled with tridodecylamine notably improved butyric acid recovery to around 60 %, with a mass flux of 14.95 ± 0.28 g/m2/h, outperforming virgin and other extractant-filled PVDF membranes. This study enhances resource efficiency and reduces industrial environmental impacts by optimizing the recovery and production of valuable chemicals from waste gases. It supports sustainable and economically viable biotechnology applications, aligning with global climate change mitigation efforts.

BACH1 impairs hepatocyte regeneration after hepatectomy with repeated ischemia/reperfusion by reprogramming energy metabolism and exacerbating oxidative stress

BTB and CNC homology 1 (BACH1) regulates biological processes, including energy metabolism and oxidative stress. Insufficient liver regeneration after hepatectomy remains an issue for surgeons. The Pringle maneuver is widely used during hepatectomy and induces ischemia/reperfusion (I/R) injury in hepatocytes. A rat model of two-thirds partial hepatectomy with repeated I/R treatment was used to simulate clinical hepatectomy with Pringle maneuver. Delayed recovery of liver function after hepatectomy with the repeated Pringle maneuver in clinic and impaired liver regeneration in rat model were observed. Highly elevated lactate levels, along with reduced mitochondrial complex III and IV activities in liver tissues, indicated that the glycolytic phenotype was promoted after hepatectomy with repeated I/R. mRNA expression profile analysis of glycolysis-related genes in clinical samples and further verification experiments in rat models showed that high BACH1 expression levels correlated with the glycolytic phenotype after hepatectomy with repeated I/R. BACH1 overexpression restricted the proliferative potential of hepatocytes stimulated with HGF. High PDK1 expression and high lactate levels, together with low mitochondrial complex III and IV activities and reduced ATP concentrations, were detected in BACH1-overexpressing hepatocytes with HGF stimulation. Moreover, HO-1 expression was downregulated, and oxidative stress was exacerbated in the BACH1-overexpressing hepatocytes with HGF stimulation. Cell experiments involving repeated hypoxia/reoxygenation revealed that reactive oxygen species accumulation triggered the TGF-β1/BACH1 axis in hepatocytes. Finally, inhibiting BACH1 with the inhibitor hemin effectively restored the liver regenerative ability after hepatectomy with repeated I/R. These results provide a potential therapeutic strategy for impaired liver regeneration after repeated I/R injury.

Kinetic regularities and a possible mechanism of ATP non-enzymatic hydrolysis induced by calix[4]arene С-107

The kinetic model of calix[4]arene-induced ATP hydrolysis was elaborated. It is assumed that calix[4]­arene С-107 molecules form a complex with nucleoside triphosphate, ensuring the release of inorganic phosphate Рі, and then switch into an inactive state. Inactive calix[4]arene molecules are no longer able to form a complex with ATP and, accordingly, to provide hydrolysis of nucleoside triphosphate. In the author’s experimental studies, it was possible to explain the kinetic properties of the reaction, namely: the insignificant output of the reaction end product Pi; the quantitative regularities of the plateau (time-wise) accumulation of the reaction product when the concentration of calix[4]arene C-107 or ATP changes; the reciprocal dependence of the ATP half conversion on its concentration; the correspondence of the initial reaction rate dependence on the calix[4]arene and ATP concentration to the Michaelis-Menten equation. The final decision regarding the molecular mechanism of calix[4]arene-induced ATP hydrolysis requires further experimental and theoretical studies. Keywords: calixarenes, empirical kinetic analysis, hydrolysis of ATP

Novel Small-Molecule ROCK2 Inhibitor GNS-3595 Attenuates Pulmonary Fibrosis in Preclinical Studies.

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease that leads to respiratory decline caused by scarring and thickening of lung tissues. Multiple pathways contribute to the fibrotic process in this disease, such as inflammation, epithelial-to-mesenchymal transition, and oxidative stress. The Rho-associated coiled-coil forming protein kinase (ROCK) signaling pathway is a key regulator of profibrotic signaling, as it affects the organization of actin-myosin and the remodeling of the extracellular matrix. ROCK1/2, a downstream effector of RhoA, is overexpressed in patients with IPF and is a promising target for IPF therapy. However, because of the hypotensive side effects of ROCK1/2 inhibitors, selective ROCK2 compounds are being explored. In this study, we report the discovery of GNS-3595, a potent and selective ROCK2 inhibitor that has ∼80-fold selectivity over ROCK1 at physiological concentrations of ATP. GNS-3595 effectively inhibited ROCK2-mediated phosphorylation of myosin light chain and reduced the expression of fibrosis-related proteins (e.g., collagen, fibronectin, and α-smooth muscle actin) in various invitro cellular models. GNS-3595 also prevented transforming growth factor β-induced fibroblast-to-myofibroblast transition. In addition, in a bleomycin-induced mouse model of pulmonary fibrosis, therapeutic exposure to GNS-3595, suppressed lung fibrosis, stabilized body weight loss, and prevented fibrosis-induced lung weight gain. Transcriptome and protein expression analysis from lung tissues showed that GNS-3595 can revert the fibrosis-related gene expression induced by bleomycin. These results indicate that GNS-3595 is a highly potent, selective, and orally active ROCK2 inhibitor with promising therapeutic efficacy against pulmonary fibrosis.

Embryonic Mice with Lung-Specific RAGE Upregulation Have Enhanced Mitochondrial Respiration

RAGE (receptor for advanced glycation end-products) represents a class of multi-ligand pattern recognition receptors highly expressed in the vertebrate lung. Our previous work demonstrated unique patterns of RAGE expression in the developing murine lung and regulation by key transcription factors including NKX2.1 and FoxA2. The current investigation employed conditional lung-specific upregulation via a TetOn transgenic mouse model (RAGE TG) and nontransgenic controls. RAGE expression was induced in RAGE TG mice throughout gestation (embryonic day, E0-E18.5) or from E15.5-E18.5 and compared to age-matched controls. High-resolution respirometry was used to assess mitochondrial respiration and context was provided by quantifying ATP and reactive oxygen species (ROS) generation. Lung lysates were also screened by immunoblotting for MAPK/PI3K signaling intermediates. RAGE upregulation increased mitochondrial oxygen consumption in the E0-E18.5 and E15.5-E18.5 groups compared to controls. RAGE TG mice also had increased ATP concentrations, which persisted even after controlling for oxygen consumption. In contrast, ROS generation was diminished in RAGE TG animals compared to controls. Lastly, in both RAGE TG groups, pERK and pp38 were significantly decreased, whereas pAKT was significantly elevated, suggesting that RAGE signaling is likely perpetuated via pAKT pathways. Together, these data demonstrate that despite lung hypoplasia in RAGE TG mice, the remaining tissue experiences a favorable shift in mitochondrial bioenergetics without excessive redox assault and a preference for AKT signaling over ERK or p38.

Enhanced triacylglycerol metabolism contributes to the efficient biosynthesis of spinosad in Saccharopolyspora spinosa

Triacylglycerol (TAG) is crucial for antibiotic biosynthesis derived from Streptomyces, as it serves as an important carbon source. In this study, the supplementation of exogenous TAG led to a 3.92-fold augmentation in spinosad production. The impact of exogenous TAG on the metabolic network of Saccharopolyspora spinosa were deeply analyzed through comparative proteomics. To optimize TAG metabolism and enhance spinosad biosynthesis, the lipase-encoding genes lip886 and lip385 were overexpressed or co-expressed. The results shown that the yield of spinosad was increased by 0.8-fold and 0.4-fold when lip886 and lip385 genes were overexpressed, respectively. Synergistic co-expression of these genes resulted in a 2.29-fold increase in the yield of spinosad. Remarkably, the combined overexpression of lip886 and lip385 in the presence of exogenous TAG elevated spinosad yields by 5.5-fold, led to a drastic increase in spinosad production from 0.036 g/L to 0.234 g/L. This study underscores the modification of intracellular concentrations of free fatty acids (FFAs), short-chain acyl-CoAs, ATP, and NADPH as mechanisms by which exogenous TAG modulates spinosad biosynthesis. Overall, the findings validate the enhancement of TAG catabolism as a beneficial strategy for optimizing spinosad production and provide foundational insights for engineering secondary metabolite biosynthesis pathways in another Streptomyces.

Membrane-targeting, ultrashort lipopeptide acts as an antibiotic adjuvant and sensitizes MDR gram-negative pathogens toward narrow-spectrum antibiotics

Globally, infections due to multi-drug resistant (MDR) Gram-negative bacterial (GNB) pathogens are on the rise, negatively impacting morbidity and mortality, necessitating urgent treatment alternatives. Herein, we report a detailed bio-evaluation of an ultrashort, cationic lipopeptide ‘SVAP9I’ that demonstrated potent antibiotic activity and acted as an adjuvant to potentiate existing antibiotic classes towards GNBs. Newly synthesized lipopeptides were screened against ESKAPE pathogens and cytotoxicity assays were performed to evaluate the selectivity index (SI). SVAP9I exhibited broad-spectrum antibacterial activity against critical MDR-GNB pathogens including members of Enterobacteriaceae (MIC 4–8 mg/L), with a favorable CC50 value of ≥100 mg/L and no detectable resistance even after 50th serial passage. It demonstrated fast concentration-dependent bactericidal action as determined via time-kill analysis and also retained full potency against polymyxin B-resistant E. coli, indicating distinct mode of action. SVAP9I targeted E. coli's outer and inner membranes by binding to LPS and phospholipids such as cardiolipin and phosphatidylglycerol. Membrane damage resulted in ROS generation, depleted intracellular ATP concentration and a concomitant increase in extracellular ATP. Checkerboard assays showed SVAP9I's synergism with narrow-spectrum antibiotics like vancomycin, fusidic acid and rifampicin, potentiating their efficacy against MDR-GNB pathogens, including carbapenem-resistant Acinetobacter baumannii (CRAB), a WHO critical priority pathogen. In a murine neutropenic thigh infection model, SVAP9I and rifampicin synergized to express excellent antibacterial efficacy against MDR-CRAB outcompeting polymyxin B. Taken together, SVAP9I's distinct membrane-targeting broad-spectrum action, lack of resistance and strong in vitro andin vivopotency in synergism with narrow spectrum antibiotics like rifampicin suggests its potential as a novel antibiotic adjuvant for the treatment of serious MDR-GNB infections.

Controversias en la fisiopatología de la hipertensión arterial.

Introduction: Purinergic receptors actively participate in the renal alterations in high blood pressure. The elevation of ATP in the renal interstitium activates purinergic receptors, constituting a fundamental pathway in the generation and persistence of arterial hypertension. Objective of the review: This article is a narrative review that aims to show the importance of new concepts in the pathophysiology of arterial hypertension. Essential points of the review: Purinergic receptors are ATP receptors; the more significant the ATP, the greater the purinergic receptors. Elevated ATP concentrations alter fundamental mechanisms related to blood pressure control, such as the pressure natriuresis mechanism and renal sodium excretion, the regulation of glomerular filtration, and the tubuloglomerular feedback mechanism. The alteration of these mechanisms decreases urinary sodium excretion. Whether influenced by genetic alterations or induced by vasoconstrictor peptides, a decrease in renal function and tubulointerstitial injury occur before the glomerulus is injured. The interaction between angiotensin II and purinergic receptors favors the progression of kidney damage. Conclusion: Kidney damage in high blood pressure is critical, so efforts should be made to control hypertension to prevent the progression of kidney damage that leads to kidney failure. To obtain better blood pressure control, developing purinergic receptor antagonists for clinical use is possible.

Safety, Tolerability, and Pharmacodynamics of AZD3366 (Optimized Human CD39L3 Apyrase) Alone and in Combination With Ticagrelor and Acetylsalicylic Acid: A Phase 1, Randomized, Placebo-Controlled Study.

ADP and ATP are importantly involved in vascular and thrombotic homeostasis, via multiple receptor pathways. Blockade of ADP P2Y12 receptors inhibits platelet aggregation and represents an effective cardiovascular disease prevention strategy. AZD3366 (APT102), a long-acting recombinant form of an optimized CD39L3 human apyrase, has effectively reduced ATP, ADP, and platelet aggregation and provided tissue protection in preclinical models, features that could be very beneficial in treating patients with cardiovascular disease. We conducted this phase 1, first-in-human study of single ascending doses of intravenous AZD3366 or placebo, including doses added to dual antiplatelet therapy with ticagrelor and acetylsalicylic acid. The primary objective was safety and tolerability; secondary and exploratory objectives included pharmacokinetics, pharmacodynamics (measured as inhibition of platelet aggregation), adenosine diphosphatase (ADPase) activity, and ATP/ADP metabolism. In total, 104 participants were randomized. AZD3366 was generally well tolerated, with no major safety concerns observed. ADPase activity increased in a dose-dependent manner with a strong correlation to AZD3366 exposure. Inhibition of ADP-stimulated platelet aggregation was immediate, substantial, and durable. In addition, there was a prompt decrease in systemic ATP concentration and an increase in adenosine monophosphate concentrations, whereas ADP concentration appeared generally unaltered. At higher doses, there was a prolongation of capillary bleeding time without detectable changes in the exvivo thromboelastometric parameters. AZD3366 was well tolerated in healthy participants and demonstrated substantial and durable inhibition of platelet aggregation after single dosing. Higher doses prolonged capillary bleeding time without detectable changes in exvivo thromboelastometric parameters. URL: https://www.clinicaltrials.gov; Unique Identifier: NCT04588727.

How Does Mg2+(aq) Interact with ATP(aq)? Biomolecular Structure through the Lens of Liquid-Jet Photoemission Spectroscopy.

Liquid-jet photoemission spectroscopy (LJ-PES) allows for a direct probing of electronic structure in aqueous solutions. We show the applicability of the approach to biomolecules in a complex environment, exploring site-specific information on the interaction of adenosine triphosphate in the aqueous phase (ATP(aq)) with magnesium (Mg2+(aq)), highlighting the synergy brought about by the simultaneous analysis of different regions in the photoelectron spectrum. In particular, we demonstrate intermolecular Coulombic decay (ICD) spectroscopy as a new and powerful addition to the arsenal of techniques for biomolecular structure investigation. We apply LJ-PES assisted by electronic-structure calculations to study ATP(aq) solutions with and without dissolved Mg2+. Valence photoelectron data reveal spectral changes in the phosphate and adenine features of ATP(aq) due to interactions with the divalent cation. Chemical shifts in Mg 2p, Mg 2s, P 2p, and P 2s core-level spectra as a function of the Mg2+/ATP concentration ratio are correlated to the formation of [Mg(ATP) 2]6-(aq), [MgATP]2-(aq), and [Mg2ATP](aq) complexes, demonstrating the element sensitivity of the technique to Mg2+-phosphate interactions. The most direct probe of the intermolecular interactions between ATP(aq) and Mg2+(aq) is delivered by the emerging ICD electrons following ionization of Mg 1s electrons. ICD spectra are shown to sensitively probe ligand exchange in the Mg2+-ATP(aq) coordination environment. In addition, we report and compare P 2s data from ATP(aq) and adenosine mono- and diphosphate (AMP(aq) and ADP(aq), respectively) solutions, probing the electronic structure of the phosphate chain and the local environment of individual phosphate units in ATP(aq). Our results provide a comprehensive view of the electronic structure of ATP(aq) and Mg2+-ATP(aq) complexes relevant to phosphorylation and dephosphorylation reactions that are central to bioenergetics in living organisms.

Immunomodulatory effects of laser-synthesized nanodiamonds on peripheral blood mononuclear cells: evaluation of unconjugated, PEGylated, and antibody-conjugated formulations

The application of laser-synthesized nanodiamonds (LNDs) is of great interest to biomedical researchers and drug developers because this emerging method of synthesis yields nanodiamonds of consistent size (&amp;lt;5 nm diameter) and surface chemistry that can be functionalized to perform a staggering range of highly specialized tasks. The present study assessed the threshold at which LNDs in various conjugations and concentrations triggered immune responses and cytotoxicity in peripheral mononuclear blood cells from healthy donors, as assessed by changes in ATP concentrations and induced secretion of the cytokines IFN-γ, IL-6 and TNF-α. Conjugations assessed were raw (unconjugated) NDs, PEGylated (PEG5k-NDs), and antibody conjugated to goat anti-mouse antibodies (IgG-NDs). Concentrations of each conjugation were prepared and tested at 50.0, 10.0, 2.0, 0.4, and 0.08 μg/mL. Results showed that pegylated and raw NDs were well tolerated, with the indicators of inflammation or minimal cytotoxicity emerging only at the highest concentrations tested (50.0 μg/mL). IgG-NDs showed signs of inflammatory responses at the two highest concentrations tested (10.0 and 50.0 μg/mL). There was some evidence that the dilutant vehicle used for ND suspension may have contributed to the immune response. All three ND configurations increased ATP concentration in a dose-dependent manner, up to a concentration of 10.0 μg/mL. At the highest concentration (50.0 μg/mL), the ND solutions showed minimal signs of cytotoxicity. Conclusion from this testing suggest that LNDs are likely to offer substantial utility in biomedical applications because of their capacity to evade the immune response at concentrations at least as high as 2.0 μg/mL and potentially up to 50.0 μg/mL.

Membrane protein guided and ATP-gated dual module DNA nanodevice for amplified fluorescence labeling of cancer cells

The occurrence and progression of tumors are accompanied by changes in both the microenvironment and cancer cells. Therefore, the detection of extracellular alert molecule accumulation, as well as the identification of abnormal cancer biomarkers both contribute to the accurate localization of individual cancer cells. Here, we have designed a cancer cell fluorescence labeling nanodevice with a membrane protein targeting domain and extracellular ATP-fueled amplification switch. The AND logic-based nanodevice light-up the cancer cell membrane only in the coexistence of target membrane proteins and abnormal ATP concentration. We demonstrated the ability of the nanodevice to selectively label target cells in a cell mixture supplemented with ATP at concentrations within the range in the tumor microenvironment (1–5×10−4 M). Additionally, the modular design of DNA nanodevices enables broad application to different cancer cells by replacing them with corresponding membrane protein aptamers. Our fluorescence labeling nanodevice with signal amplification shows promise in serving as an imaging tool for visualizing the impact of ATP regulation on cancer evolution.

New concepts in the physiopathology of hypertension. Purinergic receptors

Hypertension is a major risk of morbidity and mortality in patients when it is uncontrolled. In spite of improved therapies currently available for blood pressure control, their complications are far away from being accomplished. Therefore, chronic renal failure is frequently observed in hypertensive patients. Thus, insights on mechanisms that may contribute to arterial pressure control should be studied to prevent life-threatening cardiovascular disorders. Purinergic receptors have been recognized in the physiopathology of hypertension; this review summarizes their participation in the renal abnormalities of the kidney in hypertension. Several studies have suggested the activation of renal purinergic receptors under an elevated interstitial ATP milieu as a fundamental pathway that leads to generation and maintained hypertension. Elevated ATP concentration alters fundamental mechanisms involved in the long-term control of blood pressure such as pressure natriuresis, autoregulation of glomerular filtration rate and renal blood flow, as well as increased tubule-glomerular feedback responses, overall, these alterations decrease sodium excretion; in addition, the expression of ATP receptors is modified. Under a genetical background, ATP induces the production of vasoactive compounds, decreases renal function and induces tubulointerstitial injury before glomerular damage. Simultaneously, a deleterious interaction between angiotensin II and purinergic receptors lead to the progression of renal damage.

The toxic effects induced by benzethonium chloride on Daphnia carinata over two generations: Resistance and higher sublethal toxicity

With the widespread utilization of the sanitizing product benzethonium chloride (BEC) throughout the coronavirus pandemic, concerns have emerged regarding its potential hazards. Nevertheless, the long-term and multigenerational toxic effects of BEC on aquatic organisms remains unexplored. This study investigates acute and chronic toxicity, oxidative stress, mitochondrial membrane potential, ATP concentrations, and gene expression using Daphnia carinata as the model organism. Meanwhile, hierarchical clustering analysis was utilized to investigate phenotypic effects among different treatment groups. The integrated biomarker response index version 2 (IBRv2) was employed to estimate the deviation in toxic effects over two generations. These results indicated that D. carinata in the second generation exhibited higher survival rate and lower levels of oxidative stress than the first generation. However, the higher sublethal effects were found in the second generation as follows, the weakened growth performance, mitochondrial membrane potential depolarization, reduced ATP concentrations, and down-regulated gene expression. The mitochondrial toxicity induced by BEC may account for the distinct toxic effects exhibited in two generations. The findings here can assist with the evaluation of potential risk for BEC on aquatic organisms, and provide new insight into the cross-generational toxicity mechanisms of pollutants in aquatic ecosystems.

Greater intramuscular metabolic perturbations contribute to faster muscle fatigue development in males than females during intermittent isometric exercise

INTRODUCTION: Previous studies reported faster performance fatigability in males than females during isometric exercise, ultimately prolonging time to task failure in the latter at the same relative intensity. Several authors suggested anatomical and physiological factors as primary determinants, but it remains unknown whether exercise-related accumulation of metabolites within skeletal muscle differentially affects fatigue development in female and males. PURPOSE: This study aimed to investigate intramuscular metabolic perturbations during fatiguing intermittent isometric knee-extensor exercise in males and females. Herein, we tested the hypothesis that greater metabolic perturbation during intermittent isometric exercise results in greater fatigue development in males compared to females. Methods: Fifteen males (M)(26±2y) and fifteen eumenorrheic females (F)(24±3y) visited the laboratory twice. During visit 1, isometric knee-extensors critical torque (CT) was estimated by a 5-min all-out test. In visit 2, participants performed intermittent isometric knee-extensor exercises to task failure at 110% of CT. To determine knee-extensors magnitude and etiology of fatigue maximal voluntary isometric contraction (MVIC), voluntary activation (VA) and potentiated twitches (St) amplitudes were evaluated before (PRE), at 9min (MID), and at task failure (POST). At the same time points, intramuscular pH and concentrations of ATP, PCr, Cr and La were determined in vastus lateralis muscle biopsies. Results: Time to task failure was shorter in M than F (1017±498 vs 1511±506s; P&lt;.01). At PRE, MVIC torque was higher in M than F (259±70 vs 152±24Nm; P&lt;.001). Relative decline in MVIC torque from PRE to MID was greater in M than F (-43±9 vs -34±8% from PRE; P&lt;.05) but reached similar decline at POST (-55±7 vs -53±6% from PRE). VA decreased throughout the test similarly in both sexes (P&lt;.001). St loss from PRE was higher in M than F (-45±13 vs -37±15%; P&lt;.05) at MID whereas no sex differences were observed at POST. Muscle pH decreased at a similar rate in M and F during the test (P&lt;.03). Muscle [ATP] did not change from PRE to MID or POST. Muscle [Cr] increased at a similar rate in M and F during the test (P&lt;.01). Muscle [PCr] was lower in M than F at any time point (P&lt;.03). At MID, [La] increased to a greater extent in M than F (P&lt;.01) with no between-sex differences at POST. CONCLUSION: Males showed greater fatigue development than females associated with greater metabolic perturbation during intermittent isometric exercise performed at same relative intensity. Higher PCr depletion and higher La accumulation suggest females were less fatigable than males due to higher glycolytic rate and less intramuscular inorganic phosphate concentration. The present work was funded by a Travelling Fellowship grant JEBTF2210859 to MC from The Company Of Biologists Limited. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Apical pH regulates calcium-activated chloride secretion across human airway epithelia

Anion secretion across airway epithelia contributes to host defense by increasing airway surface liquid (ASL) volume and pH. Anion channels in the apical membrane of airway epithelia include Ca2+-activated Cl− channels (CaCCs) and cystic fibrosis transmembrane conductance regulator (CFTR) channels. Mutations in the CFTR gene that encode nonfunctional CFTR channels cause cystic fibrosis (CF); thus, activating CaCCs may restore anion secretion in people with CF. ATP secreted into the ASL activates purinergic receptors, leading to an increase in intracellular Ca2+ (Cai2+) and the opening of CaCCs. Data from docking simulations suggest that the protonation state of ATP influences its affnity for purinergic receptors, therefore we tested the hypothesis that ASL pH influences the effcacy of ATP to activate CaCCs in airway epithelia. In saline solutions buffered with 5 mM ATP, titration experiments revealed a pKa of ~6.9 at 37°C. Thus, ATP exists in its protonated ATP3− and deprotonated ATP4− in ASL that can range from pH 6 to pH 7.5. To determine the effect of pH on ATP-stimulated Cl− secretion through CaCCs, we measured Cl− secretion across CF epithelia generated by several ATP concentrations with apical pH-6.00, -6.70, and -7.40 solutions. As pH became alkaline, the EC50 for the relationship between [ATP] and Cl− secretion decreased. Using the Henderson-Hasselbalch equation and the pKa for ATP, we determined the relationship between ATP4− and Cl− secretion. This analysis revealed that regardless of apical pH values, the relationship between [ATP4−] and Cl− secretion aligned to a single experimental fit. These data suggest that pH regulates the CaCC response by deprotonating ATP. To examine the pH dependence of purinergic receptor activation, we measured ATP-induced Cai2+ responses in acutely dissociated human airway epithelial cells loaded with FURA-2 and perfused with pH-7.40 or -6.50 solutions. Separate experiments measuring intracellular pH in pH-7.40 or 6.50 solutions informed Kd values for FURA-2 experiments. With an [ATP] that induces similar levels of Cl− secretion from pH 6.00 to pH 7.40 (100 μM ATP), we observed similar Cai2+ responses for pH-7.40 and -6.50 solutions. However, when we repeated the experiment with an [ATP] that induces pH-sensitive Cl− secretion (10 μM ATP), we observed larger Ca2+ responses with pH-7.40 solutions than with pH-6.50 solutions. These data indicate that pH influences purinergic receptor activation near the pKa of ATP, a finding consistent with ATP4− activating purinergic receptors. These data have implications in CF and airway inflammation. In CF, decreased CFTR-mediated HCO−3 secretion acidifies the ASL, thus a large portion of ATP will exist in the protonated ATP3− species requiring a higher total [ATP] to open CaCCs. Inflammatory cytokines that cause airway inflammation increase the ASL pH, therefore a larger portion of ATP will exist in the deprotonated ATP4− species requiring less total [ATP] to open CaCCs. Cystic Fibrosis Foundation Research Development Program. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.