• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2001년도 학술 발표회 진행표 및 논문초록
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• pp.26-26
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• 2001

Inactivation of N-type calcium current has been reported to be both voltage dependent and Ca$\^$2＋/ dependent. We have investigated the effects of Ba$\^$2＋/ and Ca$\^$2＋/ on N-channel inactivation in rat superior cervical ganglion neurons using the whole cell configuration of patch clamp technique. Inactivation was larger in Ca$\^$2＋/ than in Ba$\^$2＋/ even with 20 mM BAPTA.(omitted)

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1997년도 학술발표회
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• pp.17-17
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• 1997

We investigated the relationship between the voltage-operated calcium channel current and the corresponding [Ca$^{2＋}$]i change (Ca$^{2＋}$-transient) in guinea-pig gastric myocyte. Fluorescence microspectroscopy was combined with conventional whole-cell patch clamp technique and fura-2 (80 $\mu$M) was added into the CsCl-rich pipette solution.(omitted)

• The Korean Journal of Physiology and Pharmacology
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• 제21권2호
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• pp.215-223
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• 2017

The effects of acidic pH on several voltage-dependent ion channels, such as voltage-dependent $K^+$ and $Ca^{2+}$ channels, and hyperpolarization-gated and cyclic nucleotide-activated cation (HCN) channels, were examined using a whole-cell patch clamp technique on mechanically isolated rat mesencephalic trigeminal nucleus neurons. The application of a pH 6.5 solution had no effect on the peak amplitude of voltage-dependent $K^+$currents. A pH 6.0 solution slightly, but significantly inhibited the peak amplitude of voltage-dependent $K^+$ currents. The pH 6.0 also shifted both the current-voltage and conductance-voltage relationships to the depolarization range. The application of a pH 6.5 solution scarcely affected the peak amplitude of membrane currents mediated by HCN channels, which were profoundly inhibited by the general HCN channel blocker $Cs^+$ (1 mM). However, the pH 6.0 solution slightly, but significantly inhibited the peak amplitude of HCN-mediated currents. Although the pH 6.0 solution showed complex modulation of the current-voltage and conductance-voltage relationships, the midpoint voltages for the activation of HCN channels were not changed by acidic pH. On the other hand, voltage-dependent $Ca^{2+}$ channels were significantly inhibited by an acidic pH. The application of an acidic pH solution significantly shifted the current-voltage and conductance-voltage relationships to the depolarization range. The modulation of several voltage-dependent ion channels by an acidic pH might affect the excitability of mesencephalic trigeminal nucleus neurons, and thus physiological functions mediated by the mesencephalic trigeminal nucleus could be affected in acidic pH conditions.

• 대한수의학회지
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• 제34권1호
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• pp.25-36
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• 1994

The inward tail current after a short depolarizing pulse has been known as Na-Ca exchange current activated by intracellular calcium which forms late plateau of the action potential in rabbit atrial myocytes. Chloride conductance which is also dependent upon calcium concentration has been reported as a possible tail current in many other excitable tissues. Thus, in order to investigate the exsitance of the calcium activated chloride current and its contribution to tail current, whole cell voltage clamp measurement has been made in single atrial cells of the rabbit. The current was recorded during repolarization following a brief 2 ms depolarizing pulse to +40mV from a holding potential of -70mV. When voltage-sensitive transient outward current was blocked by 2 mM 4-aminopyridine or replacement potassium with cesium, the tail current were abolished by ryanodine$(1{\mu}M)$ or diltiazem$(10{\mu}M)$ and turned out to be calcium dependent. The magnitudes of the tail currents were increased when intracellular chloride concentration was increased to 131 mM from 21 mM. The current was decreased by extracellular sodium reduction when intracellular chloride concentration was low(21 mM), but it was little affected by extracellular sodium reduction when intracellual chloride concentration was high(131 mM). The current-voltage relationship of the difference current before and after extracellular sodium reduction, shows an exponential voltage dependence with the largest magnitude of the current occurring at negative potentials, with is similar to current-voltage relationship at negative potentials, which is similar to current-voltage relationship of Na-Ca exchange current. The current was also decreased by $10{\mu}M$ niflumic acid and 1 mM bumetanide, which is well known anion channel blockers. The reversal potentials shifted according to changes in chloride concentration. The current-voltage relationships of the niflumic acid-sensitive currents in high and low concentration of chloride were well fitted to those predicted as chloride current. From the above results, it is concluded that calcium activated chloride component exists in the tail current with Na-Ca exchange current and it shows the reversal of tail current. Therefore it is thought that in the physiologic condition it leads to rapid end of action potential which inhibits calcium influx and it contributes to maintain the low intracellular calcium concentration with Na-Ca exchange mechanism.

• The Korean Journal of Physiology and Pharmacology
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• 제15권5호
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• pp.285-289
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• 2011

Shilajit, a medicine herb commonly used in Ayurveda, has been reported to contain at least 85 minerals in ionic form that act on a variety of chemical, biological, and physical stressors. The substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis (Vc) are involved in orofacial nociceptive processing. Shilajit has been reported to be an injury and muscular pain reliever but there have been few functional studies of the effect of Shilajit on the SG neurons of the Vc. Therefore, whole cell and gramicidin-perfotrated patch clamp studies were performed to examine the action mechanism of Shilajit on the SG neurons of Vc from mouse brainstem slices. In the whole cell patch clamp mode, Shilajit induced short-lived and repeatable inward currents under the condition of a high chloride pipette solution on all the SG neurons tested. The Shilajit-induced inward currents were concentration dependent and maintained in the presence of tetrodotoxin (TTX), a voltage gated $Na^+$ channel blocker, CNQX, a non-NMDA glutamate receptor antagonist, and AP5, an NMDA receptor antagonist. The Shilajit-induced responses were partially suppressed by picrotoxin, a $GABA_A$ receptor antagonist, and totally blocked in the presence of strychnine, a glycine receptor antagonist, however not affected by mecamylamine hydrochloride (MCH), a nicotinic acetylcholine receptor antagonist. Under the potassium gluconate pipette solution at holding potential 0 mV, Shilajit induced repeatable outward current. These results show that Shilajit has inhibitory effects on the SG neurons of Vc through chloride ion channels by activation of the glycine receptor and $GABA_A$ receptor, indicating that Shilajit contains sedating ingredients for the central nervous system. These results also suggest that Shilajit may be a potential target for modulating orofacial pain processing.

• The Korean Journal of Physiology and Pharmacology
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• 제10권3호
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• pp.131-135
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• 2006

Coeruleo-vestibular pathway which connects locus coeruleus and vestibular nuclei is noradrenergic. This study was designed to elucidate the effects of phenylephrine on the spontaneous activity of acutely isolated medial vestibular nuclear neurons of rat by whole-cell patch-clamp technique. Sprague-Dawley rats, aged 14 to 16 days, were used. After enzymatic digestion, dissociated medial vestibular neurons were transferred to a recording chamber mounted on an inverted microscope, and spontaneous action potentials were recorded by standard patch-clamp techniques. In current-clamp mode, the frequency of spontaneous action potential of medial vestibular nuclear neurons was decreased by phenylephrine (n=15). Phenylephrine increased the amplitude of afterhyperpolarization without changes in the resting membrane potential and spike width. In voltage-clamp mode, the whole potassium currents of the medial vestibular nuclear neurons were increased by phenylephrine (n=12). These experimental results suggest that ${\alpha}-receptor$ mediates the inhibitory effects on the neuronal activity of the medial vestibular nuclear neuron.

• International Journal of Oral Biology
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• 제36권2호
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• pp.71-78
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• 2011

Using whole cell current- and voltage-clamp recording we investigated the characteristics and pharmacology of group I metabotropic glutamate receptor (mGluR)-mediated responses in rat medial vestibular nucleus (MVN) neurons. In current clamp conditions, activation of mGluR I by application of the group I mGluR agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) induced a direct excitation of MVN neurons that is characterized by depolarization and increased spontaneous firing frequency. To identify which of mGluR subtypes are responsible for the various actions of DHPG in MVN, we used two subtype-selective antagonists. (S)-(+)- alpha-amino-a-methylbenzeneacetic acid (LY367385) is a potent competitive antagonist that is selective for mGluR1, whereas 2-methyl-6-(phenylethynyl)-pyridine (MPEP) is a potent noncompetitive antagonist that is selective for mGluR5. In voltage clamp conditions, DHPG application increased the frequency of spontaneous and miniature inhibitory postsynaptic currents (IPSCs) but had no effect on amplitude distributions. Antagonism of the DHPG-induced increase of miniature IPSCs required the blockade of both mGluR1 and mGluR5. DHPG application induced an inward current, which can be enhanced under depolarized conditions. DHPG-induced current was blocked by LY367385, but not by MPEP. Both LY367385 and MPEP antagonized the DHPG-induced suppression of the calcium activated potassium current ($I_{AHP}$). These data suggest that mGluR1 and mGluR5 have similar roles in the regulation of the excitability of MVN neurons, and show a little distinct. Furthermore, mGluR I, via pre- and postsynaptic actions, have the potential to modulate the functions of the MVN.

• The Korean Journal of Physiology and Pharmacology
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• 제24권5호
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• pp.433-440
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• 2020

The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) is the first relay site for the orofacial nociceptive inputs via the thin myelinated Aδ and unmyelinated C primary afferent fibers. Borneol, one of the valuable time-honored herbal ingredients in traditional Chinese medicine, is a popular treatment for anxiety, anesthesia, and antinociception. However, to date, little is known as to how borneol acts on the SG neurons of the Vc. To close this gap, the whole-cell patch-clamp technique was applied to elucidate the antinociceptive mechanism responding for the actions of borneol on the SG neurons of the Vc in mice. In the voltage-clamp mode, holding at -60 mV, the borneol-induced non-desensitizing inward currents were not affected by tetrodotoxin, a voltage-gated Na⁺ channel blocker, 6-cyano-7-nitro-quinoxaline-2,3-dione, a non-N-methyl-ᴅ-aspartate (NMDA) glutamate receptor antagonist and DL-2-amino-5-phosphonopentanoic acid, an NMDA receptor antagonist. However, borneol-induced inward currents were partially decreased in the presence of picrotoxin, a γ-aminobutyric acid (GABA)_A receptor antagonist, or strychnine, a glycine receptor antagonist, and was almost suppressed in the presence of picrotoxin and strychnine. Though borneol did not show any effect on the glycine-induced inward currents, borneol enhanced GABA-mediated responses. Beside, borneol enhanced the GABA-induced hyperpolarization under the current-clamp mode. Altogether, we suggest that borneol contributes in part toward mediating the inhibitory GABA and glycine transmission on the SG neurons of the Vc and may serve as an herbal therapeutic for orofacial pain ailments.

• International Journal of Oral Biology
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• 제32권4호
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• pp.153-160
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• 2007

The superficial dorsal horn, particularly substantia gelatinosa (SG) in the spinal cord, receives inputs from small-diameter primary afferents that predominantly convey noxious sensation. Reactive oxygen species (ROS) are toxic agents that may be involved in various neurodegenerative diseases. Recent studies indicate that ROS are also involved in persistent pain through a spinal mechanism. In the present study, whole cell patch clamp recordings were carried out on SG neurons in spinal cord slice of young rats to investigate the effects of hydrogen peroxide on neuronal excitability and excitatory synaptic transmission. In current clamp condition, tert-buthyl hydroperoxide (t-BuOOH), an ROS donor, depolarized membrane potential of SG neurons and increased the neuronal firing frequencies evoked by depolarizing current pulses. When slices were pretreated with phenyl-N-tert-buthylnitrone (PBN) or ascorbate, ROS scavengers, t-BuOOH did not induce hyperexcitability. In voltage clamp condition, t-BuOOH increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs), and monosynaptically evoked excitatory postsynaptic currents (eEPSCs) by electrical stimulation of the ipsilateral dorsal root. These data suggest that ROS generated by peripheral nerve injury can modulate the excitability of the SG neurons via pre- and postsynaptic actions.

• The Korean Journal of Physiology and Pharmacology
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• 제3권5호
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• pp.471-479
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• 1999

The Kv channel activity in vascular smooth muscle cell plays an important role in the regulation of membrane potential and blood vessel tone. It was postulated that increased blood vessel tone in hypertension was associated with alteration of Kv channel and membrane potential. Therefore, using whole cell mode of patch-clamp technique, the membrane potential and the 4-AP-sensitive Kv current in cerebral arterial smooth muscle cells were compared between normotensive rat and one-kidney, one-clip Goldblatt hypertensive rat (lK,lC-GBH rat). Cell capacitance of hypertensive rat was similar to that of normotensive rat. Cell capacitance of normotensive rat and 1K,lC-GBH rat were $20.8{\pm}2.3$ and $19.5{\pm}1.4$ pF, respectively. The resting membrane potentials measured in current clamp mode from normotensive rat and 1K,lC-GBH rat were $-45.9{\pm}1.7$ and $-38.5{\pm}1.6$ mV, respectively. 4-AP (5 mM) caused the resting membrane potential hypopolarize but charybdotoxin $(0.1\;{\mu}M)$ did not cause any change of membrane potential. Component of 4-AP-sensitive Kv current was smaller in 1K,lC-GBH rat than in normotensive rat. The voltage dependence of steady-state activation and inactivation of Kv channel determined by using double-pulse protocol showed no significant difference. These results suggest that 4-AP-sensitive Kv channels playa major role in the regulation of membrane potential in cerebral arterial smooth muscle cells and alterations of 4-AP-sensitive Kv channels would contribute to hypopolarization of membrane potential in 1K,lC-GBH rat.