• Molecules and Cells
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• 제25권2호
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• pp.242-246
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• 2008

To assess the role of $\alpha_{1G}$ T-type $Ca^{2+}$ channels in neuropathic pain after L5 spinal nerve ligation, we examined behavioral pain susceptibility in mice lacking $Ca_{V}3.1$ (${\alpha}_{1G}{^{-/-}}$), the gene encoding the pore-forming units of these channels. Reduced spontaneous pain responses and an increased threshold for paw withdrawal in response to mechanical stimulation were observed in these mice. The ${{\alpha}_{1G}}^{-/-}$ mice also showed attenuated thermal hyperalgesia in response to both low-(IR30) and high-intensity (IR60) infrared stimulation. Our results reveal the importance of ${\alpha}_{1G}$ T-type $Ca^{2+}$ channels in the development of neuropathic pain, and suggest that selective modulation of ${\alpha}_{1G}$ subtype channels may provide a novel approach to the treatment of allodynia and hyperalgesia.

• The Korean Journal of Physiology and Pharmacology
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• 제15권4호
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• pp.217-239
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• 2011

We carried out a series of experiment demonstrating the role of mitochondria in the cytosolic and mitochondrial $Ca^{2+}$ transients and compared the results with those from computer simulation. In rat ventricular myocytes, increasing the rate of stimulation (1~3 Hz) made both the diastolic and systolic [$Ca^{2+}]$ bigger in mitochondria as well as in cytosol. As L-type $Ca^{2+}$ channel has key influence on the amplitude of $Ca^{2+}$ -induced $Ca^{2+}$ release, the relation between stimulus frequency and the amplitude of $Ca^{2+}$ transients was examined under the low density (1/10 of control) of L-type $Ca^{2+}$ channel in model simulation, where the relation was reversed. In experiment, block of $Ca^{2+}$ uniporter on mitochondrial inner membrane significantly reduced the amplitude of mitochondrial $Ca^{2+}$ transients, while it failed to affect the cytosolic $Ca^{2+}$ transients. In computer simulation, the amplitude of cytosolic $Ca^{2+}$ transients was not affected by removal of $Ca^{2+}$ uniporter. The application of carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) known as a protonophore on mitochondrial membrane to rat ventricular myocytes gradually increased the diastolic [$Ca^{2+}$] in cytosol and eventually abolished the $Ca^{2+}$ transients, which was similarly reproduced in computer simulation. The model study suggests that the relative contribution of L-type $Ca^{2+}$ channel to total transsarcolemmal $Ca^{2+}$ flux could determine whether the cytosolic $Ca^{2+}$ transients become bigger or smaller with higher stimulus frequency. The present study also suggests that cytosolic $Ca^{2+}$ affects mitochondrial $Ca^{2+}$ in a beat-to-beat manner, however, removal of $Ca^{2+}$ influx mechanism into mitochondria does not affect the amplitude of cytosolic $Ca^{2+}$ transients.

• Biomolecules & Therapeutics
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• 제26권6호
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• pp.546-552
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• 2018

A comprehensive collection of proteins senses local changes in intracellular $Ca^{2+}$ concentrations ($[Ca^{2+}]_i$) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular $Ca^{2+}$ concentrations in cat esophageal smooth muscle cells. To measure $[Ca^{2+}]_i$ levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in $[Ca^{2+}]_i$ in the cells. Pretreatment with EGTA, an extracellular $Ca^{2+}$ chelator, decreased the S1P-induced increase in $[Ca^{2+}]_i$, and an L-type $Ca^{2+}$-channel blocker, nimodipine, decreased the effect of S1P. This indicates that $Ca^{2+}$ influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an $InsP_3$ receptor blocker, the S1P-evoked increase in $[Ca^{2+}]_i$ was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of $G_i$-protein, suppressed the increase in $[Ca^{2+}]_i$ evoked by S1P. These results suggest that the S1P-induced increase in $[Ca^{2+}]_i$ in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of $Ca^{2+}$ from the $InsP_3$-sensitive $Ca^{2+}$ pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular $Ca^{2+}$ via the L type $Ca^{2+}$ channel, which was dependent on activation of the $S1P_4$ receptor coupled to PTX-sensitive $G_i$ protein, via phospholipase C-mediated $Ca^{2+}$ release from the $InsP_3$-sensitive $Ca^{2+}$ pool in cat esophageal smooth muscle cells.

• Journal of Ginseng Research
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• 제35권2호
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• pp.176-190
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• 2011

There seems to be some controversy about the effect of total ginseng saponin (TGS) on the secretion of catecholamines (CA) from the adrenal gland. Therefore, the present study aimed to determine whether TGS can affect the CA release in the perfused model of the adrenal medulla isolated from spontaneously hypertensive rats (SHRs). TGS (15-150 ${\mu}g/mL$), perfused into an adrenal vein for 90 min, inhibited the CA secretory responses evoked by acetylcholine (ACh, 5.32 mM) and high $K^+$ (56 mM, a direct membrane depolarizer) in a dose- and time-dependent fashion. TGS (50 ${\mu}g/mL$) also time-dependently inhibited the CA secretion evoked by 1.1-dimethyl-4 -phenyl piperazinium iodide (DMPP; 100 ${\mu}M$, a selective neuronal nicotinic receptor agonist) and McN-A-343 (100 ${\mu}M$, a selective muscarinic M1 receptor agonist). TGS itself did not affect basal CA secretion (data not shown). Also, in the presence of TGS (50 ${\mu}g/mL$), the secretory responses of CA evoked by veratridine (a selective $Na^+$ channel activator (50 ${\mu}M$), Bay-K-8644 (an L-type dihydropyridine $Ca^{2+}$ channel activator, 10 ${\mu}M$), and cyclopiazonic acid (a cytoplasmic $Ca^{2+}$-ATPase inhibitor, 10 ${\mu}M$) were significantly reduced, respectively. Interestingly, in the simultaneous presence of TGS (50 ${\mu}g/mL$) and N${\omega}$-nitro-L-arginine methyl ester hydrochloride [an inhibitor of nitric oxide (NO) synthase, 30 ${\mu}M$], the inhibitory responses of TGS on the CA secretion evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644, cyclopiazonic acid, and veratridine were considerably recovered to the extent of the corresponding control secretion compared with the inhibitory effect of TGS-treatment alone. Practically, the level of NO released from adrenal medulla after the treatment of TGS (150 ${\mu}g/mL$) was greatly elevated compared to the corresponding basal released level. Taken together, these results demonstrate that TGS inhibits the CA secretory responses evoked by stimulation of cholinergic (both muscarinic and nicotinic) receptors as well as by direct membrane-depolarization from the isolated perfused adrenal medulla of the SHRs. It seems that this inhibitory effect of TGS is mediated by inhibiting both the influx of $Ca^{2+}$ and Na+ into the adrenomedullary chromaffin cells and also by suppressing the release of $Ca^{2+}$ from the cytoplasmic calcium store, at least partly through the increased NO production due to the activation of nitric oxide synthase, which is relevant to neuronal nicotinic receptor blockade, without the enhancement effect on the CA release. Based on these effects, it is also thought that there are some species differences in the adrenomedullary CA secretion between the rabbit and SHR.

• The Korean Journal of Physiology and Pharmacology
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• 제13권6호
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• pp.517-526
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• 2009

The present study was attempted to investigate whether polyphenolic compounds isolated from wine, which is brewed from Rubus coreanum Miquel (PCRC), may affect the release of catecholamines (CA) from the isolated perfused adrenal medulla of the spontaneously hypertensive rats (SHRs), and to establish its mechanism of action. PCRC $(20\sim180\;{\mu}g/ml)$ perfused into an adrenal vein for 90 min relatively dose-dependently inhibited the CA secretory responses to ACh (5.32 mM), high $K^+$ (56 mM), DMPP $(100\;{\mu}M)$ and McN-A-343 $(100\;{\mu}M)$. PCRC itself did not affect basal CA secretion (data not shown). Also, in the presence of PCRC $(60\;{\mu}g/ml)$, the CA secretory responses to veratridine (a selective $Na^+$ channel activator $(10\;{\mu}M)$, Bay-K-8644 (a L-type dihydropyridine $Ca^{2+}$ channel activator, $10\;{\mu}M$), and cyclopiazonic acid (a cytoplasmic $Ca^{2+}$-ATPase inhibitor, $10\;{\mu}M$) were significantly reduced, respectively. In the simultaneous presence of PCRC $(60\;{\mu}g/ml)$ and L-NAME (an inhibitor of NO synthase, $30\;{\mu}M$), the inhibitory responses of PCRC on the CA secretion evoked by ACh, high $K^+$, DMPP, and Bay-K-8644 were considerably recovered to the extent of the corresponding control secretion compared with that of PCRC-treatment alone. The level of NO released from adrenal medulla after the treatment of PCRC $(60\;{\mu}g/ml)$ was greatly elevated compared with the corresponding basal level. Taken together, these results demonstrate that PCRC inhibits the CA secretion from the isolated perfused adrenal medulla of the SHRs evoked by stimulation of cholinergic receptors as well as by direct membrane-depolarization. It seems that this inhibitory effect of PCRC is mediated by blocking the influx of calcium and sodium into the adrenal medullary chromaffin cells of the SHRs as well as by inhibition of $Ca^{2+}$ release from the cytoplasmic calcium store at least partly through the increased NO production due to the activation of NO synthase.

• 약학회지
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• 제44권6호
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• pp.499-504
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• 2000

We previously demonstrated that 6-paradol, a compound structurally related to capsaicin, showed to produce prolonged analgesia in experimental animals. The effects of 6-paradol on the release of adenosine were investigated in the rat spinal cord synaptosomes by high performance liquid chromatography. In the presence of $Ca^{++}$, adenosine was released from synaptosomes of rat spinal cord by 6-paradol and capsaicin in a dose dependent manner. Nifedifine, L-type voltage sensitive calcium channel blocker, was found to be ineffective in releasing adenosine by $10\;{\mu}M$ 6-paradol. After exposure to $10\;{\mu}M$ capsazepine, a novel capsaicin selective antagonist, the level of adenosine evoked by $10\;{\mu}M$ 6-paradol was decreased by 75%, and that evoked by $10\;{\mu}M$ capsaicin was blocked completely. These results suggest that the analgesic effect of 6-paradol might be mediated by the vanilloid (capsaicin) sensitive pathway, or the direct binding to the vanilloid receptor.

• 약학회지
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• 제44권5호
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• pp.440-447
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• 2000

Microspheres of felodipine, which is one of the calcium channel blocker using a mixture of Eudragi $t^{R}$ RL, L, E, and cellulose on the base of Eudragi $t^{R}$ RS were investigated. Cremopho $r^{R}$ was added to each preparation of polymers in order to increase the release of felodipine from microspheres. Felodipine-loaded microspheres were prepared by a solvent evaporation method, which is based on dispersion of methylene chloride containing felodipine and polymers in 0.5 w/v % polyvinyl alcohol solution. The average diameter based on the size distribution of the felodipine-loaded microspheres was observed to be ca. 40-55 ${\mu}{\textrm}{m}$. A good and smooth surface were showed in all types of the microspheres. The amount of felodipine loaded was over 90 w/w % in all types of microspheres. The dissolution profiles of felodipine from microspheres were similar with each type of polymer, and about a 60 w/w % of the total amount of felodipine loaded to microsphere was released within 7 hours. Dissolution rate of felodipine from the microsphere was increased by addition of Cremophor. After oral administration of the felodipine-loaded microspheres in PVA solution and felodipine alone in PEG solution to rats, respectively, the pharmacokinetic study revealed that the Tmax values of the microspheres were observed in the range of 0.67~l.0 hr while that of the felodipine solution was obtained 0.33 hr. In addition, the AUC of the microspheres at 0 to 7 hr was remarkably increased in comparison to that of felodipine solution. These results revealed that the microspheres based on Eudragit RS could be a good candidate for the controlled release drug delivery system for felodipine.e.e.e.

• Clinical and Experimental Pediatrics
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• 제51권7호
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• pp.771-774
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• 2008

가족성 저칼륨성 주기성 마비는 골격근에 존재하는 ion channel의 장애로 인해 저칼륨혈증과 연관되어 나타나는 주기성 이완성 마비를 보이는 드문 유전 질환이다. 이 질환의 발생에 관여하는 유전자로는 골격근육의 1q31-32 염색체에 위치하는 칼슘 채널과 나트륨 채널의 alpha subunit을 encoding하는 CACNA1S gene과 SCN4A gene이 밝혀져 있다. 국내에서도 소아의 가족성 저칼륨성 주기성 마비가 수 예 보고된 바 있지만, 유전자 분석을 통해 변이가 확인된 예는 드물다. 이에 우리는 CACNA1S의 Arg1239His 변이에 의한 저칼륨성 주기성 마비로 진단된 12세 환아의 증례를 보고하는 바이다. 이 변이는 현재까지 알려진 CACNA1S의 변이 중 비교적 흔한 것으로 알려져 있으나, 국내에서는 보고된 바가 없다. 저자들은 경구 acetazolamide와 칼륨 복용, 유발인자를 회피할 것을 교육함으로써 이 환아를 치료했으며, 현재 환아는 주기성 마비의 빈도와 중증도의 개선을 보이며 삶의 질 역시 향상되었다.

• The Korean Journal of Physiology and Pharmacology
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• 제18권5호
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• pp.431-439
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• 2014

The aim of the present study was to investigate whether ginsenoside-Rb2 (Rb2) can affect the secretion of catecholamines (CA) in the perfused model of the rat adrenal medulla. Rb2 ($3{\sim}30{\mu}M$), perfused into an adrenal vein for 90 min, inhibited ACh (5.32 mM)-evoked CA secretory response in a dose- and time-dependent fashion. Rb2 ($10{\mu}M$) also time-dependently inhibited the CA secretion evoked by DMPP ($100{\mu}M$, a selective neuronal nicotinic receptor agonist) and high $K^+$ (56 mM, a direct membrane depolarizer). Rb2 itself did not affect basal CA secretion (data not shown). Also, in the presence of Rb2 ($50{\mu}g/mL$), the secretory responses of CA evoked by veratridine (a selective $Na^+$ channel activator ($50{\mu}M$), Bay-K-8644 (an L-type dihydropyridine $Ca^{2+}$ channel activator, $10{\mu}M$), and cyclopiazonic acid (a cytoplasmic $Ca^{2+}$-ATPase inhibitor, $10{\mu}M$) were significantly reduced, respectively. Interestingly, in the simultaneous presence of Rb2 ($10{\mu}M$) and L-NAME (an inhibitor of NO synthase, $30{\mu}M$), the inhibitory responses of Rb2 on ACh-evoked CA secretory response was considerably recovered to the extent of the corresponding control secretion compared with the inhibitory effect of Rb2-treatment alone. Practically, the level of NO released from adrenal medulla after the treatment of Rb2 ($10{\mu}M$) was greatly elevated compared to the corresponding basal released level. Collectively, these results demonstrate that Rb2 inhibits the CA secretory responses evoked by nicotinic stimulation as well as by direct membrane-depolarization from the isolated perfused rat adrenal medulla. It seems that this inhibitory effect of Rb2 is mediated by inhibiting both the influx of $Ca^{2+}$ and $Na^+$ into the adrenomedullary chromaffin cells and also by suppressing the release of $Ca^{2+}$ from the cytoplasmic calcium store, at least partly through the increased NO production due to the activation of nitric oxide synthase, which is relevant to neuronal nicotinic receptor blockade.

• Archives of Pharmacal Research
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• 제25권5호
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• pp.697-703
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• 2002

We investigated that the role of nitric oxide (NO) on ischemic rats in brain and heart. Ischemia was induced by both common carotid arteries (CCA) occlusion for 24h following reperfusion. Then tissue samples were removed and measured NOx. In brain, NOx was increased by about 40% vs. normal and it was significantly inhibited by aminoguanidine, selective iNOS inhibitor. This result showed that NOx concentration was increased by iNOS. We investigated the role of $Ca^{2+}$ during ischemia. Nimodipine, L-type calcium channel blocker, didn't inhibit the increases of NOx concentration during ischemia. It suggested that increased NOx was due to calcium-independent NOS. MK-801, which N-methyl-D-aspartate (NMDA) receptor antagonist, didn't significantly prevent the increases of NOx. In heart, ischemia caused NOx decrease and it is inconsistent with NOx increase in brain. Aminoguanidine and nimodipine didnt affect on NOx decrease. But MK-801 more lowered NOx concentration than those of ischemia control group. It seemed that $Ca^{2+}$ influx in heart partially occurred via NMDA receptor and inhibited by NMDA receptor antagonist. The mean arterial pressure (MAP) in ischemic rats after 24h of CCA occlusion was decreased when compared to normal value, whereas the heart rates (HR) was not different between two groups. Aminoguanidine or MK801 had no effect on MAP or HR, but nimodipine reduced MAP. There was no difference the effects of aminoguanidine, nimodipine, or MK-801, on MAP and HR between normal rats and ischemic rats. In summary, ischemic model caused an increase of NOx concentration, suggesting that this may be produced via iNOS, which is calcium independent in brain. However in heart, ischemia decreased NOx concentration and NMDA receptor was partially involved. The basal MAP was decreased in ischemic rats but HR was not different from normal control, suggesting that increased NOx in brain of ischemic rat may result in the hypotension.