Spinal α-motoneurons directly innervate skeletal muscles and function as the final common path for movement and behavior. The processes that determine the excitability of motoneurons are critical for the execution of motor behavior. In fact, it has been noted that spinal motoneurons receive various neuromodulatory inputs, especially monoaminergic one. However, the roles of histamine and hypothalamic histaminergic innervation on spinal motoneurons and the underlying ionic mechanisms are still largely unknown. In the present study, by using the method of intracellular recording on rat spinal slices, we found that activation of either H or H receptor potentiated repetitive firing behavior and increased the excitability of spinal α-motoneurons. Both of blockage of K channels and activation of Na-Ca exchangers were involved in the H receptor-mediated excitation on spinal motoneurons, whereas the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels were responsible for the H receptor-mediated excitation. The results suggest that, through switching functional status of ion channels and exchangers coupled to histamine receptors, histamine effectively biases the excitability of the spinal α-motoneurons. In this way, the hypothalamospinal histaminergic innervation may directly modulate final motor outputs and actively regulate spinal motor reflexes and motor execution.
Animals ; Histamine ; pharmacology ; Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels ; metabolism ; Motor Neurons ; drug effects ; physiology ; Rats ; Receptors, Histamine H2 ; metabolism ; Sodium-Calcium Exchanger ; metabolism

BackgroundLipoxin A4 (LXA4) can alleviate lipopolysaccharide (LPS)-induced acute lung injury (ALI) and acute respiratory distress syndrome through promoting epithelial sodium channel (ENaC) expression in lung epithelial cells. However, how LXA4 promote ENaC expression is still largely elusive. The present study aimed to explore genes and signaling pathway involved in regulating ENaC expression induced by LXA4.

MethodsA549 cells were incubated with LPS and LXA4, or in combination, and analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) of ENaC-α/γ. Candidate genes affected by LXA4 were explored by transcriptome sequencing of A549 cells. The critical candidate gene was validated by qRT-PCR and Western blot analysis of A549 cells treated with LPS and LXA4 at different concentrations and time intervals. LXA4 receptor (ALX) inhibitor BOC-2 was used to test induction of candidate gene by LXA4. Candidate gene siRNA was adopted to analyze its influence on A549 viability and ENaC-α expression. Phosphoinositide 3-kinase (PI3K) inhibitor LY294002 was utilized to probe whether the PI3K signaling pathway was involved in LXA4 induction of candidate gene expression.

ResultsThe A549 cell models of ALI were constructed and subjected to transcriptome sequencing. Among candidate genes, N-myc downstream-regulated gene-1 (NDRG1) was validated by real-time-PCR and Western blot. NDRG1 mRNA was elevated in a dose-dependent manner of LXA4, whereas BOC-2 antagonized NDRG1 expression induced by LXA4. NDRG1 siRNA suppressed viability of LPS-treated A549 cells (treatment vs. control, 0.605 ± 0.063 vs. 0.878 ± 0.083, P = 0.040) and ENaC-α expression (treatment vs. control, 0.458 ± 0.038 vs. 0.711 ± 0.035, P = 0.008). LY294002 inhibited NDRG1 (treatment vs. control, 0.459 ± 0.023 vs. 0.726 ± 0.020, P = 0.001) and ENaC-α (treatment vs. control, 0.236 ± 0.021 vs. 0.814 ± 0.025, P < 0.001) expressions and serum- and glucocorticoid-inducible kinase 1 phosphorylation (treatment vs. control, 0.442 ± 0.024 vs. 1.046 ± 0.082, P = 0.002), indicating the PI3K signaling pathway was involved in regulating NDRG1 expression induced by LXA4.

ConclusionOur research uncovered a critical role of NDRG1 in LXA4 alleviation of LPS-induced A549 cell injury through mediating PI3K signaling to restore ENaC expression.

A549 Cells ; Acute Lung Injury ; metabolism ; Cell Cycle Proteins ; metabolism ; Cell Line ; Epithelial Sodium Channels ; metabolism ; Humans ; Intracellular Signaling Peptides and Proteins ; metabolism ; Lipopolysaccharides ; pharmacology ; Lipoxins ; pharmacology ; Signal Transduction ; drug effects

OBJECTIVETo investigate the effect of arginine vasopressin (AVP) on alveolar fluid clearance (AFC) in acute lung injury (ALI).

METHODSForty-eight healthy adult Sprague-Dawley rats were randomly divided into control group, ALI model group and AVP treatment group. The pathological changes in the lungs, lung water content, alveolar permeability and AFC were observed, and the expressions of alveolar epithelial sodium channel (ENaC) and Na⁺, K⁺-ATPase were measured.

RESULTSCompared with those in the model group, the rats treated with AVP showed significantly decreased alveolar permeability (0.27 ± 0.15 vs 0.59 ± 0.19) and lung water content (5.01 ± 1.59 vs 8.67 ± 1.79) (P<0.05) and increased AFC (23.56 ± 4.51 vs 8.28 ± 3.57) and of α-ENaC expressions (1.296 ± 0.322 vs 0.349 ± 0.141) and α1-Na⁺, K⁺-ATPase (1.421 ± 0.389 vs 0.338 ± 0.186) (P<0.05).

CONCLUSIONAVP can promote AFC in with ALI possibly by up-regulation of α-ENaC, α1-Na⁺, and K⁺-ATPase.

Acute Lung Injury ; drug therapy ; Animals ; Arginine Vasopressin ; pharmacology ; Epithelial Sodium Channels ; metabolism ; Lung ; drug effects ; pathology ; Pulmonary Alveoli ; drug effects ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Sodium-Potassium-Exchanging ATPase ; metabolism

Along with the development of economy and society, type 2 diabetic mellitus (T2DM) has become one of the most common diseases at the global level. As one of the complications of T2DM, diabetic neuropathic pain (DNP) stubbornly and chronically affects the health and life of human beings. In the pain field, dorsal root ganglion (DRG) is generally considered as the first stage of the sensory pathway where the hyperexcitability of injured neurons is associated with different kinds of peripheral neuropathic pains. The abnormal electrophysiology is mainly due to the changed properties of voltage-gated sodium channels (VGSCs) and the increased sodium currents (I(Na)). Curcumin is an active ingredient extracted from turmeric and has been demonstrated to ameliorate T2DM and its various complications including DNP effectively. The present study demonstrates that the I(Na) of small-sized DRG neurons are significantly increased with the abnormal electrophysiological characteristics of VGSCs in type 2 diabetic neuropathic pain rats. And these abnormalities can be ameliorated efficaciously by a period of treatment with curcumin.
Animals ; Curcumin ; pharmacology ; Diabetes Mellitus, Experimental ; complications ; Diabetes Mellitus, Type 2 ; complications ; Diabetic Neuropathies ; drug therapy ; Ganglia, Spinal ; cytology ; drug effects ; metabolism ; Neuralgia ; drug therapy ; Neurons ; drug effects ; metabolism ; Rats ; Sodium ; Voltage-Gated Sodium Channels ; physiology

The present study was designed to determine the effects of Guanfu base A (GFA) on the late sodium current (INa.L), transient sodium current (INa.T), HERG current (IHERG), and Kv1.5 current (IKv1.5). The values of INa.L, INa.T, IHERG and IKv1.5 were recorded using the whole-cell patch clamp technique. Compared with other channels, GFA showed selective blocking activity in late sodium channel. It inhibited INa.L in a concentration-dependent manner with an IC50 of (1.57 ± 0.14) μmol · L(-1), which was significantly lower than its IC50 values of (21.17 ± 4.51) μmol · L(-1) for the INa.T. The inhibitory effect of GFA on INa,L was not affected by 200 μmol · L(-1) H2O2. It inhibited IHERG with an IC50 of (273 ± 34) μmol · L(-1) and has slight blocking effect on IKv1.5, decreasing IKv1.5 by only 20.6% at 200 μmol · L(-1). In summary, GFA inhibited INa.L selectively and remained similar inhibition in presence of reactive oxygen species. These findings may suggest a novel molecular mechanism for the potential clinical application of GFA in the treatment of cardiovascular disorders.
Analysis of Variance ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Dose-Response Relationship, Drug ; Female ; Guinea Pigs ; HEK293 Cells ; Heart Ventricles ; drug effects ; Heterocyclic Compounds, 4 or More Rings ; pharmacology ; Humans ; Inhibitory Concentration 50 ; Male ; Membrane Potentials ; drug effects ; Myocytes, Cardiac ; metabolism ; Patch-Clamp Techniques ; Sodium Channel Blockers ; pharmacology ; Sodium Channels ; drug effects

AIM: To study the effects of crebanine on voltage-gated Na(+) channels in cardiac tissues. METHODS: Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltage-dependent Na(+) current was recorded using the whole cell voltage-clamp technique. RESULTS: Crebanine reversibly inhibited Na(+) current with an IC50 value of 0.283 mmol·L(-1) (95% confidence range: 0.248-0.318 mmol·L(-1)). Crebanine at 0.262 mmol·L(-1) caused a negative shift (about 12 mV) in the voltage-dependence of steady-state inactivation of Na(+) current, and retarded its recovery from inactivation, but did not affect its activation curve. CONCLUSION In addition to blocking other voltage-gated ion channels, crebanine blocked Na(+) channels in guinea-pig ventricular myocytes. Crebanine acted as an inactivation stabilizer of Na(+) channels in cardiac tissues.
Animals ; Aporphines ; pharmacology ; Cells, Cultured ; Down-Regulation ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Female ; Guinea Pigs ; Heart Ventricles ; cytology ; drug effects ; metabolism ; Male ; Myocytes, Cardiac ; drug effects ; metabolism ; Stephania ; chemistry ; Voltage-Gated Sodium Channel Blockers ; pharmacology ; Voltage-Gated Sodium Channels ; metabolism

FXYD6, FXYD domain containing ion transport regulator 6, has been reported to affect the activity of Na(+)/K(+)-ATPase and be associated with mental diseases. Here, we demonstrate that FXYD6 is up-regulated in hepatocellular carcinoma (HCC) and enhances the migration and proliferation of HCC cells. Up-regulation of FXYD6 not only positively correlates with the increase of Na(+)/K(+)-ATPase but also coordinates with the activation of its downstream Src-ERK signaling pathway. More importantly, blocking FXYD6 by its functional antibody significantly inhibits the growth potential of the xenografted HCC tumors in mice, indicating that FXYD6 represents a potential therapeutic target toward HCC. Altogether, our results establish a critical role of FXYD6 in HCC progression and suggest that the therapy targeting FXYD6 can benefit the clinical treatment toward HCC patients.
Animals ; Antibodies, Monoclonal ; pharmacology ; Antineoplastic Agents ; pharmacology ; Carcinoma, Hepatocellular ; drug therapy ; metabolism ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Female ; HEK293 Cells ; Humans ; Ion Channels ; antagonists & inhibitors ; metabolism ; Liver Neoplasms ; drug therapy ; metabolism ; Mice, Inbred BALB C ; Mice, Nude ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Tumor Burden ; drug effects ; Xenograft Model Antitumor Assays

OBJECTIVETo observe the effects of ginsenoside Rg1 on the functional expression of human neural stem cells (hNSCs).

METHODThe membrane electrophysiological properties and sodium and potassium ion channels in the hNSCs induced by Rg1 were analyzed using the whole-cell patch-clamp.

RESULTOn the 7th day, the neuron-like cells derived from ginsenoside Rg1 (20 mg x L(-1))-induced NSCs show: (1) The resting membrane potential: (-45.70 +/- 2.63) mV, the membrane capacitance: (26.89 +/- 1.91) pF, the membrane input impedance: (877.51 +/- 20.44) MH (P < 0.05 compared with the control group, respectively); (2) The detection rate of inward sodium current which is rapidly activated and inactivated in voltage-dependence was 50%, and its average peak value was (711.48 +/- 158.03) pA (P < 0.05 compared with the control group); (3) The outward potassium currents were composed of rapidly activated and inactivated transient outward potassium current and delayed rectifier outward potassium current, and its average peak value was (1 070.42 +/- 177.18) pA (P < 0.05 compared with the control group).

CONCLUSIONGinsenoside Rg1 can promote the functional expression and maturity of hNSCs.

Cells, Cultured ; Gene Expression ; drug effects ; Ginsenosides ; pharmacology ; Humans ; Membrane Potentials ; drug effects ; Neural Stem Cells ; cytology ; drug effects ; Patch-Clamp Techniques ; Plant Extracts ; pharmacology ; Potassium Channels ; genetics ; metabolism ; Sodium Channels ; genetics ; metabolism

OBJECTIVETo study the effects of glycyrrhetinic acid (GA) on the sodium ion channel currents (I(Na)) of rats' ventricular myocardial cells, and to explore its anti-arrhythmic mechanisms at the ion channel level.

METHODSSingle ventricular myocardial cells was isolated from SD rats. The whole cell patch clamp was used to record the effects of GA on I(Na) of rats' ventricular myocardial cells.

RESULTSGA could inhibit I(Na) of rats' ventricular myocardial cells dose-dependently. GA at 1, 5, and 10 micromol/L decreased I(Na) of rats' ventricular myocardial cells from (-4.26 +/- 0.15) nA to (-3.54 +/- 0.10) nA, (-2.19 +/- 0.09) nA, and (-1.25 +/- 0.08) nA, respectively. GA at 1, 5, and 10 micromol/L inhibited I(Na) by 16.08% +/- 2.3%, 50.82% +/- 3.56%, and 75.98% +/- 5.12%, showing statistical difference when compared with the control group (P < 0.05). GA at 10 micromol/L shifted I(Na) current-voltage curve more positively, but the activation potential and the peak potential were not changed.

CONCLUSIONGA inhibited the I(Na) of rats' ventricular myocardial cells dose-dependently, which was possibly associated with its antiarrhythmia effects.

Animals ; Glycyrrhetinic Acid ; pharmacology ; Heart Ventricles ; cytology ; metabolism ; Male ; Myocytes, Cardiac ; drug effects ; physiology ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Sodium Channels ; drug effects ; physiology

OBJECTIVETo investigate the effect of astragali injection on the expression of epithelial sodium channel in mice with acute lung injury (ALI) and explore the possible mechanism.

METHODSThirty C57BL/6 mice were randomized into 3 equal groups, namely the control group, ALI model group, and astragali injection treatment group. Twelve hours after the treatments, The wet-dry ratio (W/D) of the lungs, inflammation cell percentages in the bronchoalveolar lavage fluid (BALF) and histopathological changes of the lung tissues were examined, and the expressions of α-ENaC, TNF-α, and IL-8 mRNA in the lung tissues were determined with quantitative RT-PCR.

RESULTSThe neutrophil percentage in the BALF increased significantly in ALI group as compared with that in the other two groups. Pathological examination revealed milder lung tissue inflammation, congestion and edema in astragalus injection treatment group than in the ALI model group. Compared with those in the control group, α-ENaC mRNA expression decreased significantly while TNF-α and IL-8 mRNAs increased markedly in ALI group. In astragalus injection treatment group, the expression level of α-ENaC mRNA was higher than that in ALI group, and TNF-α and IL-8 mRNA expression lower than those in ALI group but higher than those in the control group.

CONCLUSIONAstragalus injection can ameliorate ALI in mice by inhibiting the release of inflammatory factors and up-regulating ENaC mRNA expression to promote the clearance of pulmonary edema fluid.

Acute Lung Injury ; metabolism ; Animals ; Astragalus Plant ; chemistry ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Epithelial Sodium Channels ; drug effects ; metabolism ; Interleukin-8 ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Tumor Necrosis Factor-alpha ; metabolism