• The Korean Journal of Physiology and Pharmacology
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• v.14 no.1
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• pp.51-57
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• 2010

It was hypothesized that NaF induces calcium sensitization in $Ca^{2+}$-controlled solution in permeabilized rat mesenteric arteries. Rat mesenteric arteries were permeabilized with $\beta$-escin and subjected to tension measurement. NaF potentiated the concentration-response curves to $Ca^{2+}$ (decreased $EC_{50}$ and increased $E_{max}$). Cumulative addition of NaF (4.0, 8.0 and 16 mM) also increased vascular tension in $Ca^{2+}$-controlled solution at pCa 7.0 or pCa 6.5, but not at pCa 8.0. NaF-induced vasocontraction and $GTP{\gamma}S$-induced vasocontraction were not additive. NaF-induced vasocontraction at pCa 7.0 was inhibited by pretreatment with Rho kinase inhibitors H1152 or Y27632 but not with a MLCK inhibitor ML-7 or a PKC inhibitor Ro31-8220. NaF induces calcium sensitization in a $Ca^{2+}$ dependent manner in $\beta$-escin-permeabilized rat mesenteric arteries. These results suggest that NaF is an activator of the Rho kinase signaling pathway during vascular contraction.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.11a
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• pp.156-156
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• 2002

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.156-156
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• 2002

Chronic exposure of arsenic is well known to be the cause of cardiovascular disease such as hypertension. In order to investigate the effect of arsenic on blood vessels, we examined whether arsenic affected agonist-induced contraction of aortic rings in isolated organ bath system.(omitted)

• The Korean Journal of Pain
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• v.27 no.3
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• pp.229-238
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• 2014

Background: A toxic dose of bupivacaine produces vasodilation in isolated aortas. The goal of this in vitro study was to investigate the cellular mechanism associated with bupivacaine-induced vasodilation in isolated endothelium-denuded rat aortas precontracted with phenylephrine. Methods: Isolated endothelium-denuded rat aortas were suspended for isometric tension recordings. The effects of nifedipine, verapamil, iberiotoxin, 4-aminopyridine, barium chloride, and glibenclamide on bupivacaine concentration-response curves were assessed in endothelium-denuded aortas precontracted with phenylephrine. The effect of phenylephrine and KCl used for precontraction on bupivacaine-induced concentration-response curves was assessed. The effects of verapamil on phenylephrine concentration-response curves were assessed. The effects of bupivacaine on the intracellular calcium concentration ($[Ca^{2+}]_i$) and tension in aortas precontracted with phenylephrine were measured simultaneously with the acetoxymethyl ester of a fura-2-loaded aortic strip. Results: Pretreatment with potassium channel inhibitors had no effect on bupivacaine-induced relaxation in the endothelium-denuded aortas precontracted with phenylephrine, whereas verapamil or nifedipine attenuated bupivacaine-induced relaxation. The magnitude of the bupivacaine-induced relaxation was enhanced in the 100mM KCl-induced precontracted aortas compared with the phenylephrine-induced precontracted aortas. Verapamil attenuated the phenylephrine-induced contraction. The magnitude of the bupivacaine-induced relaxation was higher than that of the bupivacaine-induced $[Ca^{2+}]_i$ decrease in the aortas precontracted with phenylephrine. Conclusions: Taken together, these results suggest that toxic-dose bupivacaine-induced vasodilation appears to be mediated by decreased calcium sensitization in endothelium-denuded aortas precontracted with phenylephrine. In addition, potassium channel inhibitors had no effect on bupivacaine-induced relaxation. Toxic-dose bupivacaine-induced vasodilation may be partially associated with the inhibitory effect of voltage-operated calcium channels.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.164.2-165
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• 2003

Chronic exposure of arsenic is well known to be the cause of cardiovascular disease such as hypertension. In order to investigate the effect of arsenic on blood vessels. we examined whether arsenic affected agonist-induced contraction of aortic rings in isolated organ bath system. Treatment with arsenite increased vasoconstriction induced by phenylephrine or serotonin in a concentration-dependent manner. (omitted)

• International Journal of Oral Biology
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• v.38 no.1
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• pp.5-12
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• 2013

Recent studies indicate that reactive oxygen species (ROS) can act as modulators of neuronal activity, and are critically involved in persistent pain primarily through spinal mechanisms. In this study, we investigated the effects of NaOCl, a ROS donor, on neuronal excitability and the intracellular calcium concentration ($[Ca^{2+}]_i$) in spinal substantia gelatinosa (SG) neurons. In current clamp conditions, the application of NaOCl caused a membrane depolarization, which was inhibited by pretreatment with phenyl-N-tert-buthylnitrone (PBN), a ROS scavenger. The NaOCl-induced depolarization was not blocked however by pretreatment with dithiothreitol, a sulfhydryl-reducing agent. Confocal scanning laser microscopy was used to confirm whether NaOCl increases the intracellular ROS level. ROS-induced fluorescence intensity was found to be increased during perfusion of NaOCl after the loading of 2',7'-dichlorofluorescin diacetate ($H_2DCF$-DA). NaOCl-induced depolarization was not blocked by pretreatment with external $Ca^{2+}$ free solution or by the addition of nifedifine. However, when slices were pretreated with the $Ca^{2+}$ ATPase inhibitor thapsigargin, NaOCl failed to induce membrane depolarization. In a calcium imaging technique using the $Ca^{2+}$-sensitive fluorescence dye fura-2, the $[Ca^{2+}]_i$ was found to be increased by NaOCl. These results indicate that NaOCl activates the excitability of SG neurons via the modulation of the intracellular calcium concentration, and suggest that ROS induces nociception through a central sensitization.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.1
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• pp.39-48
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• 2023

Spinal nerve injury causes mechanical allodynia and structural imbalance of neurotransmission, which were typically associated with calcium overload. Storeoperated calcium entry (SOCE) is considered crucial elements-mediating intracellular calcium homeostasis, ion channel activity, and synaptic plasticity. However, the underlying mechanism of SOCE in mediating neuronal transmitter release and synaptic transmission remains ambiguous in neuropathic pain. Neuropathic rats were operated by spinal nerve ligations. Neurotransmissions were assessed by whole-cell recording in substantia gelatinosa. Immunofluorescence staining of STIM1 with neuronal and glial biomarkers in the spinal dorsal horn. The endoplasmic reticulum stress level was estimated from qRT-PCR. Intrathecal injection of SOCE antagonist SKF96365 dose-dependently alleviated mechanical allodynia in ipsilateral hind paws of neuropathic rats with ED₅₀ of 18 ㎍. Immunofluorescence staining demonstrated that STIM1 was specifically and significantly expressed in neurons but not astrocytes and microglia in the spinal dorsal horn. Bath application of SKF96365 inhibited enhanced miniature excitatory postsynaptic currents in a dosage-dependent manner without affecting miniature inhibitory postsynaptic currents. Mal-adaption of SOCE was commonly related to endoplasmic reticulum (ER) stress in the central nervous system. SKF96365 markedly suppressed ER stress levels by alleviating mRNA expression of C/ EBP homologous protein and heat shock protein 70 in neuropathic rats. Our findings suggested that nerve injury might promote SOCE-mediated calcium levels, resulting in long-term imbalance of spinal synaptic transmission and behavioral sensitization, SKF96365 produces antinociception by alleviating glutamatergic transmission and ER stress. This work demonstrated the involvement of SOCE in neuropathic pain, implying that SOCE might be a potential target for pain management.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.1
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• pp.33-39
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• 2002

It has been suggested that $Ca^{2+}$ sensitization mechanisms might contribute to myogenic tone, however, specific mechanisms have not yet been fully identified. Therefore, we investigated the role of protein kinase C (PKC)- or RhoA-induced $Ca^{2+}$ sensitization in myogenic tone of the rabbit basilar vessel. Myogenic tone was developed by stretch of rabbit basilar artery. Fura-2 $Ca^{2+}$ signals, contractile responses, PKC immunoblots, translocation of PKC and RhoA, and phosphorylation of myosin light chains were measured. Stretch of the resting vessel evoked a myogenic contraction and an increase in the intracellular $Ca^{2+}$ concentration $([Ca^{2+}]_i)$ only in the presence of extracellular $Ca^{2+}$. Stretch evoked greater contraction than high $K^+$ at a given $[Ca^{2+}]_i.$ The stretch-induced increase in $[Ca^{2+}]_i$ and contractile force were inhibited by treatment of the tissue with nifedipine, a blocker of voltage-dependent $Ca^{2+}$ channel, but not with gadolinium, a blocker of stretch-activated cation channels. The PKC inhibitors, H-7 and calphostin C, and a RhoA-activated protein kinase (ROK) inhibitor, Y-27632, inhibited the stretch-induced myogenic tone without changing $[Ca^{2+}]_i.$ Immunoblotting using isoform-specific antibodies showed the presence of $PKC_{\alpha}$ and $PKC_{\varepsilon}$ in the rabbit basilar artery. $PKC_{\alpha},$ but not $PKC_{\varepsilon},$ and RhoA were translocated from the cytosol to the cell membrane by stretch. Phosphorylation of the myosin light chains was increased by stretch and the increased phosphorylation was blocked by treatment of the tissue with H-7 and Y-27632, respectively. Our results are consistent with important roles for PKC and RhoA in the generation of myogenic tone. Furthermore, enhanced phosphorylation of the myosin light chains by activation of $PKC_{\alpha}$ and/or RhoA may be key mechanisms for the $Ca^{2+}$ sensitization associated with myogenic tone in basilar vessels.

• The Korean Journal of Pharmacology
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• v.29 no.2
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• pp.263-274
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• 1993

Potassium $(K^+)$ channels are present in airway smooth muscle cells, and their activation results in hyperpolarization and relaxation. Because these effects may have therapeutic relevance to hypersensitivity and asthma, we examined the effect of a potassium channel activator, cromakalim (BRL 34915, CK) on the release of mediators from superfused tracheal and parenchymal strips after passive sensitization with $IgG_1$ antibody. Both tissues were superfused with CK $(2{\times}10^{-6}\;M)$ for 30 min and challenged with CK and antigen (Ox-HSA). Using monodispersed, partially purified, highly purified guinea pig lung mast cells, we also examined the effect of CK on mediator release from these cells after passive sensitization with $IgG_{1}$ antibody $({\alpha}-OA)$. Guinea pig lung mast cells were purified using enzyme digestion method, count current elutriation, and discontinuous Percoll density gradient. After CK pretreatment, passively sensitized mast cells were challenged with varying concentration of antigen (OA, immunological stimuli) or with varying concentration of calcium ionophore (CaI, non-immunological stimuli). Histamine (Hist) release was determined by spectrophotofluorometry, and leukotrienes (LT) by radioimmunoassy. CK pretreatment decreased Hist by 35% and LT release by 40% in the antigen-induced tracheal tissue after $IgG_1$ sensitization but did not decrease the contractile response. In the antigen-induced parenchymal tissue CK decreased Hist release by 25% but poorly decreased LT. Both immunologic and non-immunologic stimuli caused a dose-dependent release of Hist and LT from monodispersed, partially purified and highly purified lung mast cells. Verification of LT release was obtained by the use of 5-lipoxygenase inhibitor, A64077 (Zileuton). CK decreased Hist and LT release by 20% respectively in the OA-induced guinea pig lung mast cells after $IgG_1$ sensitization. The inhibitory effects of CK on the Hist and LT release in the Ox-HSA-induced airway smooth muscle tissues or in the OA-induced and CaI-induced mast cells after $IgG_1$ sensitization were completely blocked by TEA and GBC. These studies show that guinea pig lung mast cells seem to be an important contributor to LT release, and that CK (which has been known as an airway smooth muscle relaxant) can in part act to inhibit mediator release in the antigen-induced airway smooth muscle, and that CK may also act to inhibit mediator release in the OA-induced and CaI-induced highly purified mast cells. These results suggest that Hist and LT release evoked by mast cell activation might in part be associated with $K{^+}4 channel activity.

• International Journal of Oral Biology
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• v.37 no.1
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• pp.17-23
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• 2012

Recent studies indicate that reactive oxygen species (ROS) are critically involved in persistent pain primarily through spinal mechanisms, and that mitochondria are the main source of ROS in the spinal dorsal horn. To investigate whether mitochondrial ROS can induce changes in membrane excitability on spinal substantia gelatonosa (SG) neurons, we examined the effects of mitochondrial electron transport complex (ETC) substrates and inhibitors on the membrane potential of SG neurons in spinal slices. Application of ETC inhibitors, rotenone or antimycin A, resulted in a slowly developing and slight membrane depolarization in SG neurons. Also, application of both malate, a complex I substrate, and succinate, a complex II substrate, caused reversible membrane depolarization and enhanced firing activity. Changes in membrane potential after malate exposure were more prominent than succinate exposure. When slices were pretreated with ROS scavengers such as phenyl-N-tert-buthylnitrone (PBN), catalase and 4- hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), malate-induced depolarization was significantly decreased. Intracellular calcium above $100{\mu}M$ increased malateinduced depolarization, witch was suppressed by cyclosporin A, a mitochondrial permeability transition (MPT) inhibitor. These results suggest that enhanced production of spinal mitochondrial ROS can induce nociception through central sensitization.