AIMUsing GeneChip to analyze the changes in genes expression of brain potassium, sodium and calcium channels after chronic treatment with nicotine.

METHODSAnimals were treated with nicotine at the doses of 2.4 mg/kg sc. twice a day for 14 days. RNA was extracted from the whole brain samples and converted to double-stranded cDNA and then to biotinylated cRNA. The biotinylated cRNA was fragmented, and hybridized to GeneChip (Affymetrix Rat Neurobiology U34). The chips were scanned with a probe array scanner, and the data were analyzed with the Affymetrix Microarray Analysis Suite (MAS). The GeneChip data were confirmed u sing RT-PCR.

RESULTSAfter treatment with chronic nicotine, transcripts of potassium, sodium and calcium channels showed altered expression. K+ channel: outward rectifier K+ channel and Ca2(+)-activated K+ channel were down-regulated, other voltage-dependent K+ channel including Kv2.3r were up-regulated. Voltage-dependent Na+ channel: beta2 subunit was increased, alpha subunit and beta1 subunit were decreased. Beta3 subunit of Ca2+ channel was up-regulated.

CONCLUSIONChronic exposure to nicotine not only desensitized nicotinic receptors, but also effected genes expression, of important ion channels, such as sodium channels, potassium channels and calcium channels.

Animals ; Brain ; drug effects ; metabolism ; Calcium Channels ; drug effects ; metabolism ; Gene Expression ; Male ; Nicotine ; pharmacology ; Potassium Channels ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium Channels ; drug effects ; metabolism

OBJECTIVE: To investigate the mechanism of the tinnitus inducer, sodium salicylate, on voltage-gated sodium channels. METHOD: The effects of salicylate on voltage-gated sodium channels in freshly dissociated inferior colliculus neurons of rats were studied, using the whole-cell voltage clamp method. RESULT: Salicylate blocked sodium current (INa) in concentration-dependent manner (0.1-10 mmol/L). The IC50 value for the blocking action of salicylate was 1.43 mmol/L. Salicylate did not affect the conductance-voltage curve and the steady-state activation curve of INa. The steady-state INa inactivation curve of INa was shifted by about 9 mV in the hyperpolarizing direction. In addition, salicylate delayed the sodium channel recovery from INa inactivation by increasing the slow time constant. CONCLUSION Our results suggest that salicylate causes a concentration-dependent blockade of INa and shifts the INa inactivation curve to more hyperpolarized potentials, which could be related to the mechanism of salicylate-induced tinnitus.
Animals ; Inferior Colliculi ; cytology ; Male ; Neurons ; drug effects ; metabolism ; Patch-Clamp Techniques ; Rats ; Rats, Wistar ; Sodium Channels ; drug effects ; metabolism ; Sodium Salicylate ; pharmacology

OBJECTIVETo investigate the effects of docosahexaenoic acid (DHA) on sodium channel current (I(Na)) and transient outward potassium channel current (I(to)) in rat ventricular myocytes and to evaluate potential anti-arrhythmic mechanisms of DHA.

METHODSI(Na) and I(to) of individual ventricular myocytes were recorded by patch-clamp technique in whole-cell configuration at room temperature. Effects of DHA at various concentrations (0, 20, 40, 60, 80, 100 and 120 micromol/L) on I(Na) and I(to) were observed.

RESULTS(1) I(Na) was blocked in a concentration-dependent manner by DHA, stably inactivated curves were shifted to the left, and recover time from inactivation was prolonged while stably activated curves were not affected by DHA. At -30 mV, I(Na) was blocked to (1.51 ± 1.32)%, (21.13 ± 4.62)%, (51.61 ± 5.73)%, (67.62 ± 6.52)%, (73.49 ± 7.59)% and (79.95 ± 7.62)% in the presence of above DHA concentrations (all P < 0.05, n = 20), and half-effect concentration (EC(50)) of DHA on I(Na) was (47.91 ± 1.57)micromol/L. (2) I(to) were also blocked in a concentration-dependent manner by DHA, stably inactivated curves were shifted to the left, and recover time from inactivation was prolonged with increasing concentrations of DHA, and stably activated curves were not affected by DHA. At +70 mV, I(to) was blocked to (2.61 ± 0.26)%, (21.79 ± 4.85)%, (63.11 ± 6.57)%, (75.52 ± 7.26)%, (81.82 ± 7.63)% and (84.33 ± 8.25)%, respectively, in the presence of above DHA concentrations (all P < 0.05, n = 20), and the EC(50) of DHA on I(to) was (49.11 ± 2.68)micromol/L.

CONCLUSIONThe blocking effects of DHA on APD and I(to) may serve as one of the anti-arrhythmia mechanisms of DHA.

Animals ; Cells, Cultured ; Docosahexaenoic Acids ; pharmacology ; Heart Ventricles ; cytology ; Myocytes, Cardiac ; metabolism ; physiology ; Patch-Clamp Techniques ; Potassium Channels ; drug effects ; Rats ; Rats, Sprague-Dawley ; Sodium Channels ; drug effects

OBJECTIVEto investigate the effect of deoxypodophyllotoxin (DOP) on membrane potential of dorsal unpaired median neurons (DUM, neurons) and its correlation with sodium channel.

METHODSDUM neurons were labeled with DiBAC4(3). Laser scanning confocal microscope was used to monitor the changes of membrane potential at real time on these neurons that were treated with different concentrations of the DOP. The effect of sodium channel blocker tetrodotoxin (TTX) on the changes was also observed.

RESULTSmembrane potential depolarization induced by the DOP peaked at 5 min and became stabilized after 8min. After compared with fluorescence intensity without treatment, the normalized fluorescence intensity was 69.6 ± 3.0, 72.1 ± 2.7, 77.8 ± 3.6, 86.2 ± 3.1 in cells which were treated with 1, 5, 25, 125 micromol/L DOP, respectively. These numbers were significantly lower than those from untreated control cells (P < 0.01). When DUM neurons were co-incubated with 1 micromol/L TTX for 20 min, then treated with 25 micromol/L DOP, the intensity changed to 63.6 ± 5.4, which was similar to that of the control (P > 0.05). This indicated that the effect of DOP could be completely inhibited by TTX.

CONCLUSIONDOP induced membrane depolarization of DUM neurons in the range of 1 approximately 125 micromol/L and the sodium channel should be involved in this process.

Animals ; Cells, Cultured ; Ganglia, Invertebrate ; drug effects ; physiology ; Membrane Potentials ; drug effects ; physiology ; Neurons ; drug effects ; physiology ; Periplaneta ; drug effects ; physiology ; Podophyllotoxin ; analogs & derivatives ; pharmacology ; Sodium Channels ; metabolism

OBJECTIVETo study the effects of Injection Stauntoniae (IS) on voltage-gated sodium currents in dorsal root ganglion neurons and analyze its pharmacological mechanism of blocking the nerve conduction and anal gesic action.

METHODSWhole-cell patch-clamp recordings were performed in acutely isolated rat dorsal root ganglion neurons and the effects of 10% , 25% and 50 % IS on voltage-gated sodium currents were observed.

RESULTSIS inhibited the peak sodium currents in dorsal root ganglion neurons in a dose-dependent way and affected the activation and inactivation process of the channels.

CONCLUSIONThe analgesic effect of IS was presumably caused by modulation of voltage-gated sodium channels in primary sensory neurons besides structure destruction of myelin sheath and axon membrane.

Analgesics ; administration & dosage ; pharmacology ; Animals ; Drugs, Chinese Herbal ; administration & dosage ; pharmacology ; Ferns ; Ganglia, Spinal ; drug effects ; metabolism ; Injections ; Neurons ; drug effects ; metabolism ; Rats ; Sodium Channels ; drug effects

AIMTo study effect of CoCl2 pretreatment on the voltage-gated Na+ and K+ currents of the rat hippocampal neurons after acute hypoxia.

METHODSPrimarily cultured hippocampal neurons were divided into CoCl2 pretreated and non-pretreated groups. Patch clamp whole cell recording technique was used to examine Na+ and K+ currents of the hippocampal neurons.

RESULTSAfter acute hypoxia, I(Na) and I(K) of the hippocampal neurons were significantly decreased and the threshold of I(Na) was right-shifted. Pretreatment of the neurons with CoCl2 inhibited the reduction of I(Na) and I(K).

CONCLUSIONCcCl2 pretreatment alleviates the acute hypoxia-induced changes of I(Na) and I(K), which may be one of the mechanisms for the protective effect of CoCl2 on neurons.

Animals ; Animals, Newborn ; Cell Hypoxia ; Cobalt ; pharmacology ; Hippocampus ; cytology ; physiopathology ; Neurons ; drug effects ; Patch-Clamp Techniques ; Potassium Channels ; metabolism ; Rats ; Rats, Wistar ; Sodium Channels ; metabolism

OBJECTIVETo explore the effect of terbutaline on sodium transport in rat alveolar type I (ATI) and type II (ATII) cells of rats.

METHODSThe whole cell currents were recorded from ATII cells isolated from rat lungs perfused with or without amiloride (inhibitor of epithelial sodium channel) and ZnCl(2) (inhibitor of cyclic nucleotide-gated cation channel) in the whole cell recording mode using the patch-clamp technique. The effect of terbutaline on the currents was examined.

RESULTSThe main currents recorded from ATII cells were amiloride-sensitive and Zn(2+)-sensitive. The amiloride-sensitive and Zn(2+)-sensitive current shared a similar proportion (P>0.05). Both currents could be significantly increased by terbutaline (P<0.05), and the proportion of amiloride-sensitive current was 1.7 times that of Zn(2+)-sensitive current (P<0.05).

CONCLUSIONThere are functional epithelial sodium channels (ENaC) and cyclic nucleotide-gated cation channels (CNG) on freshly isolated ATII cells, both serving as the main channels for sodium transport. Terbutaline increases the absorption of alveolar fluid primarily by increasing sodium transport of ENaC and CNG on ATI and AT II cells.

Amiloride ; pharmacology ; Animals ; Chlorides ; pharmacology ; Cyclic Nucleotide-Gated Cation Channels ; antagonists & inhibitors ; drug effects ; Male ; Peptides ; pharmacology ; Pulmonary Alveoli ; cytology ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium ; metabolism ; Sodium Channels ; drug effects ; Terbutaline ; pharmacology ; Zinc Compounds ; pharmacology

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

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

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