Purinergic receptors play an important role in regulating gastrointestinal (GI) motility. Interstitial cells of Cajal (ICCs) are pacemaker cells that regulate GI smooth muscle activity. We studied the functional roles of external adenosine 5′-triphosphate (ATP) on pacemaker activity in cultured ICCs from mouse small intestines by using the whole-cell patch clamp technique and intracellular Ca²⁺ ([Ca²⁺]ᵢ) imaging. External ATP dose-dependently depolarized the resting membrane and produced tonic inward pacemaker currents, and these effects were antagonized by suramin, a purinergic P2 receptor antagonist. ATP-induced effects on pacemaker currents were suppressed by an external Na⁺-free solution and inhibited by the nonselective cation channel blockers, flufenamic acid and niflumic acid. The removal of external Ca²⁺ or treatment with thapsigargin (inhibitor of Ca²⁺ uptake into endoplasmic reticulum) inhibited the ATP-induced effects on pacemaker currents. Spontaneous [Ca²⁺]ᵢ oscillations were enhanced by external ATP. These results suggest that external ATP modulates pacemaker activity by activating nonselective cation channels via external Ca²⁺ influx and [Ca²⁺]ᵢ release from the endoplasmic reticulum. Thus, it seems that activating the purinergic P2 receptor may modulate GI motility by acting on ICCs in the small intestine.
Adenosine ; Adenosine Triphosphate ; Animals ; Endoplasmic Reticulum ; Flufenamic Acid ; Interstitial Cells of Cajal ; Intestine, Small ; Membranes ; Mice ; Muscle, Smooth ; Niflumic Acid ; Pacemaker, Artificial ; Receptors, Purinergic ; Receptors, Purinergic P2 ; Suramin ; Thapsigargin

Autism spectrum disorder is a rapidly increasing heterogeneous neurodevelopmental syndrome, remarked by persistent deficit in social communication, and restricted, repetitive patterns of behavior and interest. Lately, maternal immune activation and micgroglial dysfunction in the developing brain have been gaining mounting evidence and leading to studies of various novel agents as potential treatment options. A few immunomodulatory treatment options—luteolin, minocycline, suramin, vitamin D, gut microbiota—are discussed in the current article, regarding the current understanding of their mechanisms and evidence for potential clinical use. More studies are warranted to understand their exact mechanisms of action and to verify efficacy and safety in human subjects.
Autism Spectrum Disorder* ; Autistic Disorder* ; Brain ; Humans ; Immunomodulation ; Microglia* ; Minocycline ; Suramin ; Vitamin D

BACKGROUND/AIMS: The internal anal sphincter (IAS) plays an important role in maintaining continence and a number of neurotransmitters are known to regulate IAS tone. The aim of this study was to determine the relative importance of the neurotransmitters involved in the relaxant and contractile responses of the porcine IAS. METHODS: Responses of isolated strips of IAS to electrical field stimulation (EFS) were obtained in the absence and presence of inhibitors of neurotransmitter systems. RESULTS: Contractile responses of the sphincter to EFS were unaffected by the muscarinic receptor antagonist, atropine (1 muM), but were almost completely abolished by the adrenergic neuron blocker guanethidine (10 muM). Contractile responses were also reduced (by 45% at 5 Hz, P < 0.01) following desensitisation of purinergic receptors with alpha,beta-methylene-ATP (10 muM). In the presence of guanethidine, atropine, and alpha,beta-methylene-ATP, the remaining relaxatory responses to EFS were examined. These responses were not altered by the cyclooxygenase inhibitor, indomethacin (5 muM), the vasoactive intestinal polypeptide receptor antagonist, [D-p-Cl-Phe6,Leu17]-vasoactive intestinal peptide (PheLeu-VIP; 100 nM), or the purinoceptor antagonists, 8-phenyltheophyline (P1 receptors) or suramin (P2 receptors). However, relaxation responses were reduced by Nomega-nitro-L-arginine (L-NNA; 100 muM), an inhibitor of nitric oxide synthesis (40-50% reduction), zinc protoprophyrin IX (10 muM), an inhibitor of carbon monoxide synthesis (20-40% reduction), and also propargylglycine (30 muM) and aminooxyacetic acid (30 muM), inhibitors of hydrogen sulphide synthesis (15-20% reduction). CONCLUSIONS: Stimulation of IAS efferent nerves releases excitatory and inhibitory neurotransmitters: noradrenaline is the predominant contractile transmitter with a smaller component from ATP, whilst 3 gases mediate relaxation responses to EFS, with the combined contributions being nitric oxide > carbon monoxide > hydrogen sulfide.
Adenosine Triphosphate ; Adrenergic Neurons ; Aminooxyacetic Acid ; Anal Canal* ; Atropine ; Autonomic Pathways ; Carbon Monoxide* ; Carbon* ; Gases ; Guanethidine ; Hydrogen Sulfide* ; Hydrogen* ; Indomethacin ; Neurotransmitter Agents* ; Nitric Oxide* ; Norepinephrine ; Prostaglandin-Endoperoxide Synthases ; Purinergic Antagonists ; Receptors, Muscarinic ; Receptors, Purinergic ; Relaxation* ; Suramin ; Vasoactive Intestinal Peptide ; Zinc

OBJECTIVETo investigate the effect of suramin on inflammatory response in pulmonary tissue and peripheral blood in septic mice.

METHODSTwenty-four male C57BL/6 mice were randomly divided into two groups, and suramin(5 mg/kg) or normal saline was intravenously injected 30 min before LPS(5 mg/kg)infusion, respectively. The contents of TNF-α and IL-6 in pulmonary tissue and peripheral blood were detected by ELISA. Suramin or saline-pretreated human mononuclear THP-1 cells were treated with 100 ng/mL LPS in vitro. The expression of TNF-α and IL-6 mRNA and the activity of NF-κB were analyzed by quantitative PCR and Western blotting at different time points after LPS treatment, respectively.

RESULTSCompared with the saline group, the TNF-α and IL-6 levels in pulmonary tissue and peripheral blood were significantly reduced in suramin group at 24 h after LPS treatment(all P<0.01); while there was no significant difference at 72 h between two groups(all P>0.05). The expression of TNF-α, IL-6 mRNA and the activity of NF-κB was decreased in suramin group at different time points after LPS treatment.

CONCLUSIONSuramin can protect LPS-induced acute lung injury through down-regulation of systemic and pulmonary pro-inflammatory factors, which may be associated with the inhibition of NF-κB activity.

Acute Lung Injury ; drug therapy ; Animals ; Cell Line ; Down-Regulation ; Gene Expression Regulation ; Inflammation ; drug therapy ; Interleukin-6 ; metabolism ; Lipopolysaccharides ; Lung ; drug effects ; Male ; Mice ; Mice, Inbred C57BL ; NF-kappa B ; metabolism ; RNA, Messenger ; metabolism ; Sepsis ; drug therapy ; Suramin ; pharmacology ; Tumor Necrosis Factor-alpha ; metabolism

Reactive oxygen species (ROS) and nitrogen species (RNS) are implicated in cellular signaling processes and as a cause of oxidative stress. Recent studies indicate that ROS and RNS are important signaling molecules involved in nociceptive transmission. Xanthine oxidase (XO) system is a well-known system for superoxide anions (O2(.-)) generation, and sodium nitroprusside (SNP) is a representative nitric oxide (NO) donor. Patch clamp recording in spinal slices was used to investigate the role of O2(.-) and NO on substantia gelatinosa (SG) neuronal excitability. Application of xanthine and xanthine oxidase (X/XO) compound induced membrane depolarization. Low concentration SNP (10 microM) induced depolarization of the membrane, whereas high concentration SNP (1 mM) evoked membrane hyperpolarization. These responses were significantly decreased by pretreatment with phenyl N-tert-butylnitrone (PBN; nonspecific ROS and RNS scavenger). Addition of thapsigargin to an external calcium free solution for blocking synaptic transmission, led to significantly decreased X/XO-induced responses. Additionally, X/XO and SNP-induced responses were unchanged in the presence of intracellular applied PBN, indicative of the involvement of presynaptic action. Inclusion of GDP-beta-S or suramin (G protein inhibitors) in the patch pipette decreased SNP-induced responses, whereas it failed to decrease X/XO-induced responses. Pretreatment with n-ethylmaleimide (NEM; thiol-alkylating agent) decreased the effects of SNP, suggesting that these responses were mediated by direct oxidation of channel protein, whereas X/XO-induced responses were unchanged. These data suggested that ROS and RNS play distinct roles in the regulation of the membrane excitability of SG neurons related to the pain transmission.
Animals ; Calcium ; Ethylmaleimide ; Humans ; Membranes ; Neurons* ; Nitric Oxide ; Nitrogen* ; Nitroprusside ; Oxidative Stress ; Rats* ; Reactive Oxygen Species* ; Substantia Gelatinosa* ; Superoxides ; Suramin ; Synaptic Transmission ; Thapsigargin ; Tissue Donors ; Xanthine ; Xanthine Oxidase

OBJECTIVETo test the different contrctile responses of extracellular nucleotides, such as ATP, UTP and nucleotide uridine adenosine tetraphosphate (Up4A) in gastric longitudinal muscle (LM) and circular muscle (CM). Examined the effect of P2X and P2Y receptor antagonists (in this study, we used IP5I and suramin) and cyclooxygenase inhibitor (indomethacin) on Up4A induced contractile responses in LM and CM.

METHODSThe rats were sacrificed and the stomachs were opened to gain LM and CM. Using organ bath system to assess contrctile responses of smooth muscle.

RESULTSUp4A could induce contractile responses in both CM and LM, which were similar with ATP and UTP. IP5 did not attenuate Up4A could induce contractions in both LM and CM, but suramin and indomethacin significantly inhibited Up4A contraction in CM, but not in LM.

CONCLUSIONOur results suggest that extracellular nucleosides and their inhibitors induce different responses between LM and CM.

Adenosine Triphosphate ; pharmacology ; Animals ; Dinucleoside Phosphates ; pharmacology ; Indomethacin ; Muscle Contraction ; Muscle, Smooth ; physiology ; Nucleotides ; pharmacology ; Rats ; Suramin ; Uridine Triphosphate ; pharmacology

To understand the roles of purinergic receptors and cellular molecules below the receptors in the vascular inflammatory response, we determined if extracellular nucleotides up-regulated chemokine expression in vascular smooth muscle cells (VSMCs). Human aortic smooth muscle cells (AoSMCs) abundantly express P2Y1, P2Y6, and P2Y11 receptors, which all respond to extracellular nucleotides. Exposure of human AoSMCs to NAD+ , an agonist of the human P2Y11 receptor, and NADP+ as well as ATP, an agonist for P2Y1 and P2Y11 receptors, caused increase in chemokine (C-C motif) ligand 2 gene (CCL2) transcript and CCL2 release; however, UPT did not affect CCL2 expression. CCL2 release by NAD+ and NADP+ was inhibited by a concentration dependent manner by suramin, an antagonist of P2-purinergic receptors. NAD+ and NADP+ activated protein kinase C and enhanced phosphorylation of mitogen-activated protein kinases and Akt. NAD(+)- and NADP(+)-mediated CCL2 release was significantly attenuated by SP6001250, U0126, LY294002, Akt inhibitor IV, RO318220, GF109203X, and diphenyleneiodium chloride. These results indicate that extracellular nucleotides can promote the proinflammatory VSMC phenotype by up-regulating CCL2 expression, and that multiple cellular elements, including phosphatidylinositol 3-kinase, Akt, protein kinase C, and mitogen-activated protein kinases, are involved in that process.
Adenosine Triphosphate ; Butadienes ; Chromones ; Humans ; Indoles ; Maleimides ; Mitogen-Activated Protein Kinases ; Morpholines ; Muscle, Smooth, Vascular ; Myocytes, Smooth Muscle ; Nitriles ; Nucleotides ; Onium Compounds ; Phenotype ; Phosphatidylinositol 3-Kinase ; Phosphorylation ; Protein Kinase C ; Receptors, Purinergic ; Suramin

It is well-known that electrical field stimulation (EFS)-induced contraction is mediated by a cholinergic mechanism and other neurotransmitters. NO, ATP, calcitonin gene-related peptide (CGRP), and substance P are released by EFS. To investigate the purinergic mechanism involved in the EFS-induced contraction, purinegic receptors antagonists were used. Suramine, a non-selective P2 receptor antagonist, reduced the contraction induced by EFS. NF023 (10(-7)~10(-4) M), a selective P2X antagonist, inhibited the contraction evoked by EFS. Reactive blue (10(-6)~10(-4) M), selective P2Y antagonist, also blocked the contraction in a dose-dependent manner. In addition, P2X agonist alpha,beta-methylene 5'-adenosine triphosphate (alphabetaMeATP, 10(-7)~10(-5) M) potentiated EFS-induced contraction in a dose-dependent manner. P2Y agonist adenosine 5'-[beta-thio]diphosphate trilithium salt (ADPbetaS, 10(-7)~10(-5) M) also potentiated EFS-induced contractions in a dose-dependent manner. Ecto-ATPase activator apyrase (5 and 10 U/ml) reduced EFS-induced contractions. Inversely, 6-N,N-diethyl-D-beta,gamma-dibromomethylene 5'-triphosphate triammonium (ARL 67156, 10(-4) M) increased EFS-induced contraction. These data suggest that endogenous ATP plays a role in EFS-induced contractions which are mediated through both P2X-receptors and P2Y-receptors stimulation in cat esophageal smooth muscle.
Adenosine ; Adenosine Triphosphatases ; Adenosine Triphosphate ; Animals ; Apyrase ; Calcitonin Gene-Related Peptide ; Calcium ; Cats ; Contracts ; GTP-Binding Proteins ; Muscle, Smooth ; Neurotransmitter Agents ; Polyphosphates ; Substance P ; Suramin

BACKGROUND: Hypoxic pulmonary vasoconstriction (HPV) is unique to pulmonary circulation but the mechanism remains elusive. Red blood cells (RBCs) are known to augment HPV and to release more ATP as oxygen content falls. Leukotrienes constrict smooth muscle and could be important for the regulation of the pulmonary circulation. Hence we hypothesized that ATP and leukotrienes are mediators of HPV produced during acute alveolar hypoxia. METHODS: In forty Sprague-Dawley rats, lungs were isolated and perfused. We administered ATP (10 micrometer) to the ATP group (n = 8), the ATP antagonist, suramin (100 micrometer) to the suramin group (n = 8), leukotriene C4 (LTC4, 5 microgram) to the LTC4 group (n = 8), the LTC4 antagonist, LY171883 (20 micrometer) to the LY171883 group (n = 8), and LTC4 (5 microgram) + ATP (10 micrometer) to the LTC4 + ATP group (n = 8) during normoxic ventilation. HPV responses were induced by three hypoxic challenges for 5 minutes separated by 5 minutes of ventilation with a normoxic gas mixture. Baseline pulmonary artery pressure change after exposure to each drug and hypoxic pressor response between a period 21% normoxic gas ventilation and that of 3% hypoxic gas ventilation were measured. RESULTS: ATP and LTC4 + ATP increased baseline pulmonary artery pressures but LTC4 did not alter it. ATP did not affect hypoxic pressor response. Suramin, LY171883 and LTC4 + ATP inhibited the pressor response to hypoxia. LTC4 increased hypoxic pressor response. CONCLUSIONS: In isolated rat lungs, HPV may be mediated by ATP and LTC4 appears more likely to be a modulator than a mediator of HPV.
Acetophenones ; Adenosine Triphosphate ; Animals ; Anoxia ; Erythrocytes ; Leukotriene C4 ; Leukotrienes ; Lung ; Muscle, Smooth ; Oxygen ; Pulmonary Artery ; Pulmonary Circulation ; Rats ; Rats, Sprague-Dawley ; Suramin ; Tetrazoles ; Vasoconstriction ; Ventilation

In this study, the mechanism by which Suramin inhibits the replication of epidemic encephalitis B virus was explored to provide a theoretical basis for its further application in clinical practice. After viral infection of HepG2 and IMR-32 cells, different concentrations of Suramin were added to the culture media, and then the cultural supernatants and infected cells were collected 48 h later. For the evaluation of the curative effect, cytopathic effect (CPE), virus titers, the expression of viral protein and viral RNA were determined by Western blot, RT-PCR and in vitro RNA synthesis, respectively. At the concentration of 50 microg/ml of Suramin, HepG2 and IMR-32 infected with epidemic encephalitis B virus decreased by 51.8% and 0.03% respectively, as compared with controls. It was suggested that expression of encephalitis B virus proteins NS3 and E was notably reduced by Suramin. This is especially true of E protein. At RNA level, however, no difference in RNA virus was found between Suramin-treated virus and non-treated cells. Our results suggest that Suramin can inhibit viral replication by blocking the production of viral proteins.
Antiviral Agents ; pharmacology ; Carcinoma, Hepatocellular ; pathology ; virology ; Cell Line, Tumor ; Encephalitis Virus, Japanese ; Humans ; Liver Neoplasms ; pathology ; virology ; RNA Helicases ; RNA, Viral ; drug effects ; Serine Endopeptidases ; Suramin ; pharmacology ; Viral Envelope Proteins ; biosynthesis ; genetics ; Viral Nonstructural Proteins ; biosynthesis ; genetics ; Virus Replication ; drug effects