Dual effect of glycine on isolated rat suprachiasmatic neurons

1991 ◽  
Vol 260 (2) ◽  
pp. C213-C218 ◽  
Author(s):  
C. Ito ◽  
M. Wakamori ◽  
N. Akaike
Keyword(s):  
Neural Activity ◽  
Excitatory Amino Acids ◽  
Pharmacological Properties ◽  
Dependent Manner ◽  
Intracellular Recordings ◽  
Induced Current ◽  
Patch Clamp Technique ◽  
Dual Effect ◽  
Concentration Dependent Manner ◽  
Inhibitory Neurotransmitter

Pharmacological properties of strychnine-sensitive and -insensitive glycine receptors have been investigated in rat suprachiasmatic nucleus (SCN) neurons. Because the SCN neurons were too small for stable intracellular recordings by the glass-microelectrode technique, a conventional whole cell mode patch-clamp technique was employed on the acutely dissociated SCN neurons. Dissociated SCN neurons were morphologically heterogeneous and could be distinguished into several types. All cells responded to glycine in a concentration-dependent manner. The glycine-induced current was primarily Cl- sensitive and competitively blocked by strychnine. The SCN neurons also responded to excitatory amino acids: glutamate, quisqualate, kainate, and N-methyl-D-aspartate (NMDA). Responses to glutamate and aspartate, which are endogenous neurotransmitter candidates, were enhanced by adding glycine. Glycine especially augmented the maximum response to NMDA in a full concentration range. 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX) did not suppress the strychnine-sensitive glycine response but did suppress the strychnine-insensitive NMDA response in a competitive manner for glycine. The results suggest that glycine influences neural activity in the SCN as a classical inhibitory neurotransmitter and an excitatory neuromodulator.

scholarly journals Neuroepithelial bodies in mammalian lung express functional serotonin type 3 receptor

2001 ◽  
Vol 281 (4) ◽  
pp. L931-L940 ◽  
Author(s):  
X. W. Fu ◽  
D. Wang ◽  
J. Pan ◽  
S. M. Farragher ◽  
V. Wong ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Dependent Manner ◽  
Induced Current ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Whole Cell Patch Clamp ◽  
Cell Plasma ◽  
Neuroepithelial Body ◽  
Inward Currents ◽  
Type 3

Serotonin (5-HT) type 3 receptor (5-HT3-R) is a ligand-gated ion channel found primarily in the central and peripheral nervous system. We report expression and functional characterization of 5-HT3-R in pulmonary neuroepithelial body (NEB) cells. Using nonisotopic in situ hybridization, we demonstrate expression of 5-HT3-R mRNA in NEB cells in the lungs of different mammals (hamster, rabbit, mouse, and human). Dual immunocytochemistry (for 5-HT and 5-HT3-R) and confocal microscopy localized 5-HT3-R on NEB cell plasma membrane from rabbit. The electrophysiological characteristics of 5-HT3-R in NEB cells were studied in fresh slices of neonatal hamster lung using the whole cell patch-clamp technique. Application of the 5-HT (5–150 μM) and 5-HT3-R agonist 2-methyl-5-HT (5–150 μM) induced inward currents in a concentration-dependent manner. The 5-HT-induced current was blocked (76.5 ± 5.9%) by the specific 5-HT3-R antagonist ICS-205–930 (50 μM), whereas katanserin and p-4-iodo- N-{2-[4-(methoxyphenyl)-1-piperazinyl]ethyl}- N-2-pyridinylbenzamide had minimal effects. Forskolin had no effect on desensitization and amplitude of the 5-HT-induced current. The reduction of Ca2+ and Mg2+ in the extracellular solution enhanced the amplitude of the 5-HT-induced current because of slower desensitization. Our studies suggest that 5-HT3-R in NEB cells may function as an autoreceptor and may potentially be involved in modulation of hypoxia signaling.

Expression of 5-HT3 receptors in PC12 cells treated with NGF and 8-Br-cAMP

1992 ◽  
Vol 67 (4) ◽  
pp. 812-819 ◽  
Author(s):  
K. Furukawa ◽  
N. Akaike ◽  
H. Onodera ◽  
K. Kogure
Keyword(s):  
Pc12 Cells ◽  
Reversal Potential ◽  
Inward Rectification ◽  
Inactivation Kinetics ◽  
Induced Response ◽  
Dependent Manner ◽  
Induced Current ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inward Current

1. To determine the functional development of neurons, we applied nerve growth factor (NGF) or 8-bromo-cyclic-adenosine monophosphate (8-Br-cAMP) to PC12 cells and recorded the 5-hydroxytryptamine (5-HT)-induced response by the use of a patch-clamp technique. 2. Cultured PC12 cells expressed 5-HT-sensitive receptors, which are almost absent in untreated cells, in the continuous presence of NGF or 8-Br-cAMP for a period of 10 days. 3. Activation of the receptors by 5-HT produced a transient inward current. In a K(+)-free solution, the reversal potential (E5-HT) of I5-HT was +10.3 mV, and the current-voltage (I-V) relation showed inward rectification at positive potentials. 4. The permeability ratio for monovalent cations was Na+:Li+:K+:Rb+:Cs+ = 1:1.19:0.89:0.94:0.91, indicating that a 5-HT-induced current is passing through the ligand-gated large cation channel. 5. 2-Methyl-5-HT, a specific 5-HT3 agonist, induced a similar inward current, even though the current amplitude was smaller and the activation and inactivation kinetics were slower than those of 5-HT. 6. ICS-205-930, a specific 5-HT3 antagonist, inhibited the 5-HT-induced current in a concentration-dependent manner with a noncompetitive inhibition profile. Spiperone, a 5-HT1 and 5-HT2 families antagonist, and ketanserine, 5-HT2 family antagonist, did not affect the 5-HT-induced response. 7. The time to peak (tp) as well as fast and slow time constants (tau if and tau is) decreased with increasing 5-HT concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of glucose deprivation on NMDA-induced current and intracellular Ca2+ in rat substantia nigra neurons

1996 ◽  
Vol 75 (2) ◽  
pp. 740-749 ◽  
Author(s):  
Y. Nakashima ◽  
H. Ishibashi ◽  
N. Harata ◽  
N. Akaike
Keyword(s):  
Substantia Nigra ◽  
Outward Current ◽  
Glucose Deprivation ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Induced Current ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inward Current ◽  
Rat Substantia Nigra

1. The effects of glucose deprivation on N-methyl-D-asparate (NMDA)-induced current (INMDA) and the intracellular free Ca2+ concentration ([Ca2+]i) in the acutely dissociated rat substantia nigra neurons were investigated using the nystatin-perforated patch-clamp technique under voltage clamp and the microfluometry with a fluorescent probe, Indo-1. 2. Application of NMDA induced a peak and a successive steady-state inward current, and an outward current immediately after washout at a holding potential of -40 mV. The amplitudes of the three current components of INMDA were increased by increasing the concentrations of NMDA with half-maximum concentrations (EC50s) of 1.1 x 10(-4) M, 1.2 x 10(-4) M, and 1.6 x 10(-4) M, respectively. 3. The reversal potentials of the peak inward and outward currents were -4 +/- 3 (SE) mV and -76 +/- 2 mV, respectively. The latter was close to the theoretical K+ equilibrium potential (-82 mV). 4. The outward current was potentiated by increase in extracellular Ca2+ concentration and was blocked by Cs+ internal solution and suppressed by 5 x 10(-3) M tetraethylammonium chloride and 10(-7) M charybdotoxin, indicating that it was Ca(2+)-activated K+ current. 5. Application of NMDA increased [Ca2+]i in a concentration-dependent manner with an EC50 of 3.9 x 10(-5) M. 6. Depriving the external solution of glucose induced a slowly developing outward current and increased the basal level of [Ca2+]i. It also prolonged the NMDA-induced outward current without affecting the peak inward current, and prolonged the NMDA-induced increase in [Ca2+]i without changing the peak [Ca2+]i. 7. These findings suggest that the deprivation of glucose did not affect the NMDA-induced influx of Ca2+ into the cells, but it inhibited Ca2+ clearance by affecting the efflux of Ca2+ to the extracellular space, reuptake into the intracellular Ca2+ stores, and/or active extrusion from intracellular stores.

scholarly journals Oxytocin Inhibits T-Type Calcium Current of Human Decidual Stromal Cells

2005 ◽  
Vol 90 (7) ◽  
pp. 4191-4197 ◽  
Author(s):  
Bo Liu ◽  
Stephen J. Hill ◽  
Raheela N. Khan
Keyword(s):  
Stromal Cells ◽  
Calcium Current ◽  
Elective Cesarean Section ◽  
Dependent Manner ◽  
Uterine Contractility ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inactivation Curve ◽  
Decidual Cells ◽  
Elective Cesarean

Abstract Context: Little is known about the crosstalk between the decidua and myometrium in relation to human labor. The hormone oxytocin (OT) is considered to be a key mediator of uterine contractility during parturition, exerting some of its effects through calcium channels. Objective: The objective was to characterize the effect of OT on the T-type calcium channel in human decidual stromal cells before and after the onset of labor. Design: The nystatin-perforated patch-clamp technique was used to record inward T-type calcium current (ICa(T)) from acutely dispersed decidual stromal cells obtained from women at either elective cesarean section [CS (nonlabor)] or after normal spontaneous vaginal delivery [SVD (labor)]. Setting: These studies took place at the University of Nottingham Medical School. Results: I Ca(T) of both SVD and CS cells were blocked by nickel (IC50 of 5.6 μm) and cobalt chloride (1 mm) but unaffected by nifedipine (10 μm). OT (1 nm to 3.5 μm) inhibited ICa(T) of SVD cells in a concentration-dependent manner, with a maximal inhibition of 79.0% compared with 26.2% in decidual cells of the CS group. OT-evoked reduction of ICa(T) was prevented by preincubation with the OT antagonist L371,257 in the SVD but not CS group. OT, in a concentration-dependent manner, displaced the steady-state inactivation curve for ICa(T) to the left in the SVD group with no significant effect on curves of the CS group. Conclusion: Inhibition of ICa(T) by OT in decidual cells obtained during labor may signify important functional remodeling of uterine signaling during this period.

gamma-Aminobutyric acid-induced response in rat dissociated paratracheal ganglion cells

1992 ◽  
Vol 67 (5) ◽  
pp. 1367-1374 ◽  
Author(s):  
S. Itabashi ◽  
K. Aibara ◽  
H. Sasaki ◽  
N. Akaike
Keyword(s):  
Response Curve ◽  
Ganglion Cells ◽  
Aminobutyric Acid ◽  
Equilibrium Potential ◽  
Induced Response ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Concentration Response Curve

1. The pharmacologic properties of gamma-aminobutyric acid (GABA)-induced Cl- current (ICl) were studied in the paratracheal ganglion cells freshly dissociated from 7- to 10-day-old rat trachea in a whole-cell recording mode by the use of a conventional patch-clamp technique. 2. GABA- and muscimol-induced currents increased sigmoidally in a concentration-dependent manner, and both currents reversed at approximately -3 mV, which was close to the Cl- equilibrium potential (ECl). 3. Strychnine (STR) at low concentration and bicuculline (BIC) inhibited GABA response competitively, whereas STR at the higher concentrations, benzylpenicillin (PCG), or picrotoxin (PTX) inhibited noncompetitively. Inhibition of GABA response by PCG but not other antagonists was voltage dependent, indicating that PCG acts as a Cl- channel blocker. 4. The concentration-response curve of pentobarbital sodium (PB)-induced ICl was bell shaped. At concentrations higher than 10(-3) M, both the peak and plateau currents decreased, and a transient "hump" current appeared immediately after washing out PB. In the presence of PB, the concentration-response curve of GABA shifted toward left without changing the maximum response. 5. Although diazepam (DZP) at concentration used did not induce a response, it potentiated the GABA response in a concentration-dependent manner between 10(-8) and 10(-6) M. DZP also caused a parallel shift toward left in the concentration-response curve of GABA. 6. PB or DZP further enhanced the GABA response in the presence of the other agent. 7. It is concluded that the properties of GABAA receptors in the paratracheal ganglion cells are essentially similar to those reported in other preparations.

Direct block of cloned hKv1.5 channel by cytochalasins, actin-disrupting agents

2005 ◽  
Vol 289 (2) ◽  
pp. C425-C436 ◽  
Author(s):  
Bok Hee Choi ◽  
Jung-Ah Park ◽  
Kyung-Ryoul Kim ◽  
Ggot-Im Lee ◽  
Yong-Tae Lee ◽  
...  
Keyword(s):  
Actin Filament ◽  
Cytochalasin B ◽  
Delayed Rectifier ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Independent Manner ◽  
Concentration Dependent Manner ◽  
Voltage Range ◽  
Whole Cell Patch Clamp ◽  
Voltage Dependent

The action of cytochalasins, actin-disrupting agents on human Kv1.5 channel (hKv1.5) stably expressed in Ltk− cells was investigated using the whole cell patch-clamp technique. Cytochalasin B inhibited hKv1.5 currents rapidly and reversibly at +60 mV in a concentration-dependent manner with an IC50 of 4.2 μM. Cytochalasin A, which has a structure very similar to cytochalasin B, inhibited hKv1.5 (IC50 of 1.4 μM at +60 mV). Pretreatment with other actin filament disruptors cytochalasin D and cytochalasin J, and an actin filament stabilizing agent phalloidin had no effect on the cytochalasin B-induced inhibition of hKv1.5 currents. Cytochalasin B accelerated the decay rate of inactivation for the hKv1.5 currents. Cytochalasin B-induced inhibition of the hKv1.5 channels was voltage dependent with a steep increase over the voltage range of the channel's opening. However, the inhibition exhibited voltage independence over the voltage range in which channels are fully activated. Cytochalasin B produced no significant effect on the steady-state activation or inactivation curves. The rate constants for association and dissociation of cytochalasin B were 3.7 μM/s and 7.5 s−1, respectively. Cytochalasin B produced a use-dependent inhibition of hKv1.5 current that was consistent with the slow recovery from inactivation in the presence of the drug. Cytochalasin B (10 μM) also inhibited an ultrarapid delayed rectifier K+ current ( IK,ur) in human atrial myocytes. These results indicate that cytochalasin B primarily blocks activated hKv1.5 channels and endogenous IK,ur in a cytoskeleton-independent manner as an open-channel blocker.

Effects of extracellular ATP on ICa, [Ca2+]i, and contraction in isolated ferret ventricular myocytes

1993 ◽  
Vol 264 (3) ◽  
pp. C702-C708 ◽  
Author(s):  
Y. Qu ◽  
H. M. Himmel ◽  
D. L. Campbell ◽  
H. C. Strauss
Keyword(s):  
Action Potential ◽  
Ventricular Myocytes ◽  
Ventricular Myocardium ◽  
Inhibitory Effect ◽  
Extracellular Atp ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
The Right

The effects of extracellular ATP on the voltage-activated "L-type" Ca current (ICa), action potential, resting and transient intracellular Ca2+ levels, and cell contraction were examined in enzymatically isolated myocytes from the right ventricles of ferrets. With the use of the whole cell patch-clamp technique, extracellular ATP (10(-7) to 10(-3) M) inhibited ICa in a time- and concentration-dependent manner. ATP decreased the peak amplitude of ICa without altering the residual current at the end of 500-ms clamp steps. The concentration-response relationship for ATP inhibition of ICa was well described by a conventional Michaelis-Menten relationship with a half-maximal inhibitory concentration of 1 microM and a maximal effect of 50%. Consistent with its inhibitory effect on ICa, ATP hyperpolarized the plateau phase and shortened the action potential duration. In fura-2-loaded myocytes, extracellular ATP did not change the resting myoplasmic Ca2+ levels; however, when current was elicited under voltage-clamp conditions, ATP both decreased the myoplasmic intracellular Ca2+ transient and inhibited the degree of cell shortening. Our results suggest that ATP could be a genuine and potent extracellular modulator of cardiac function in ferret ventricular myocardium.

Mg2+ Inhibition of ATP-Activated Current in Rat Nodose Ganglion Neurons: Evidence That Mg2+ Decreases the Agonist Affinity of the Receptor

1997 ◽  
Vol 77 (6) ◽  
pp. 3391-3395 ◽  
Author(s):  
Chaoying Li ◽  
Robert W. Peoples ◽  
Forrest F. Weight
Keyword(s):  
Nodose Ganglion ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Agonist Affinity ◽  
Nodose Ganglion Neurons ◽  
Whole Cell Patch Clamp ◽  
Activation Rate ◽  
The Right ◽  
Ganglion Neurons

Li, Chaoying, Robert W. Peoples, and Forrest F. Weight. Mg2+ inhibition of ATP-activated current in rat nodose ganglion neurons: evidence that Mg2+ decreases the agonist affinity of the receptor. J. Neurophysiol. 77: 3391–3395, 1997. The effect of Mg2+ on ATP-activated current in rat nodose ganglion neurons was investigated with the use of the whole cell patch-clamp technique. Mg2+ decreased the amplitude of ATP-activated current in a concentration-dependent manner over the concentration range of 0.25–8 mM, with a 50% inhibitory concentration value of 1.5 mM for current activated by 10 μM ATP. Mg2+ shifted the ATP concentration-response curve to the right in a parallel manner, increasing the 50% effective concentration value for ATP from 9.2 μM in the absence of added Mg2+ to 25 μM in the presence of 1 mM Mg2+. Mg2+ increased the deactivation rate of ATP-activated current without changing its activation rate. The observations are consistent with an action of Mg2+ to inhibit ATP-gated ion channel function by decreasing the affinity of the agonist binding site on these receptors.

Resveratrol inhibits Kv2.2 currents through the estrogen receptor GPR30-mediated PKC pathway

2013 ◽  
Vol 305 (5) ◽  
pp. C547-C557 ◽  
Author(s):  
Wen-Hao Dong ◽  
Jia-Chen Chen ◽  
Yan-Lin He ◽  
Jia-Jie Xu ◽  
Yan-Ai Mei
Keyword(s):  
Molecular Mechanisms ◽  
Cerebellar Granule Cells ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Α Subunit ◽  
Inactivation Curve ◽  
Hek 293 ◽  
Nongenomic Action ◽  
Α Subunits

Resveratrol (REV) is a naturally occurring phytoalexin that inhibits neuronal K+ channels; however, the molecular mechanisms behind the effects of REV and the relevant α-subunit are not well defined. With the use of patch-clamp technique, cultured cerebellar granule cells, and HEK-293 cells transfected with the Kv2.1 and Kv2.2 α-subunits, we investigated the effect of REV on Kv2.1 and Kv2.2 α-subunits. Our data demonstrated that REV significantly suppressed Kv2.2 but not Kv2.1 currents with a fast, reversible, and mildly concentration-dependent manner and shifted the activation or inactivation curve of Kv2.2 channels. Activating or inhibiting the cAMP/PKA pathway did not abolish the inhibition of Kv2.2 current by REV. In contrast, activation of PKC with phorbol 12-myristate 13-acetate mimicked the inhibitory effect of REV on Kv2.2 by modifying the activation or inactivation properties of Kv2.2 channels and eliminated any further inhibition by REV. PKC and PKC-α inhibitor completely eliminated the REV-induced inhibition of Kv2.2. Moreover, the effect of REV on Kv2.2 was reduced by preincubation with antagonists of GPR30 receptor and shRNA for GPR30 receptor. Western blotting results indicated that the levels of PKC-α and PKC-β were significantly increased in response to REV application. Our data reveal, for the first time, that REV inhibited Kv2.2 currents through PKC-dependent pathways and a nongenomic action of the oestrogen receptor GPR30.

Gramicidin perforated patch-clamp technique reveals glycine-gated outward chloride current in dissociated nucleus solitarii neurons of the rat

1994 ◽  
Vol 72 (3) ◽  
pp. 1103-1108 ◽  
Author(s):  
J. S. Rhee ◽  
S. Ebihara ◽  
N. Akaike
Keyword(s):  
Patch Clamp ◽  
Hill Coefficient ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Perforated Patch ◽  
Clamp Technique ◽  
Outward Currents ◽  
Patch Technique ◽  
Perforated Patch Clamp

1. The inhibitory response of exogenously applied glycine was investigated in freshly dissociated rat nucleus tractus solitarii neurons under whole cell configuration using new perforated patch-clamp technique termed "gramicidin perforated patch technique," which maintains intact intracellular Cl- concentrations. 2. Using the gramicidin perforated patch technique, at a holding potential (VH) of -45 mV, glycine induced outward currents in a concentration-dependent manner with a EC50 of 4.0 x 10(-5) M and at a Hill coefficient of 1.5. In contrast, using the nystatin perforated patch technique, glycine induced inward currents at the same VH in a concentration-dependent manner with an EC50 of 4.9 x 10(-5) M and at a Hill coefficient of 1.2. 3. The glycine-induced outward currents were blocked by strychnine in a concentration dependent manner with an IC50 of 2.2 x 10(-8) M. The blockade was competitive. 4. The current-voltage relationship for the 10(-5) M glycine response showed a clear outward rectification. 5. Ten-fold change of extracellular Cl- with a large impermeable anion resulted in a 65 mV shift of the reversal potential of glycine-induced currents (EGly), indicating that the membrane behaves like a Cl- electrode in the presence of glycine. 6. The intracellular Cl- activity calculated from the EGly ranged from 7.3 to 18.2 mM, with a mean value of 13.3 mM. 7. The values of EGly in the individual neurons were significantly negative to the resting membrane potentials, suggesting the existence of active transport of Cl-.

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