• The Korean Journal of Physiology and Pharmacology
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• v.27 no.5
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• pp.481-491
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• 2023

The β subunits of high voltage-gated calcium channels (HGCCs) are essential for optimal channel functions such as channel gating, activation-inactivation kinetics, and trafficking to the membrane. In this study, we report for the first time the potent blood pressure-reducing effects of peptide fragments derived from the β subunits in anesthetized and non-anesthetized rats. Intravenous administration of 16-mer peptide fragments derived from the interacting regions of the β1 [cacb1(344-359)], β2 [cacb2(392-407)], β3 [cacb3(292-307)], and β4 [cacb4(333-348)] subunits with the main α-subunit of HGCC decreased arterial blood pressure in a dose-dependent manner for 5-8 min in anesthetized rats. In contrast, the peptides had no effect on the peak amplitudes of voltage-activated Ca²⁺ current upon their intracellular application into the acutely isolated trigeminal ganglion neurons. Further, a single mutated peptide of cacb1(344-359)-cacb1(344-359)_K357R-showed consistent and potent effects and was crippled by a two-amino acid-truncation at the N-terminal or C-terminal end. By conjugating palmitic acid with the second amino acid (lysine) of cacb1(344-359)_K357R (named K2-palm), we extended the blood pressure reduction to several hours without losing potency. This prolonged effect on the arterial blood pressure was also observed in non-anesthetized rats. On the other hand, the intrathecal administration of acetylated and amidated cacb1(344-359)_K357R peptide did not change acute nociceptive responses induced by the intradermal formalin injection in the plantar surface of rat hindpaw. Overall, these findings will be useful for developing antihypertensives.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.1
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• pp.93-103
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• 2024

Satellite glial cells (SGCs), a major type of glial cell in the autonomic ganglia, closely envelop the cell body and even the synaptic regions of a single neuron with a very narrow gap. This structurally unique organization suggests that autonomic neurons and SGCs may communicate reciprocally. Glial Ca²⁺ signaling is critical for controlling neural activity. Here, for the first time we identified the machinery of store-operated Ca²⁺ entry (SOCE) which is critical for cellular Ca²⁺ homeostasis in rat sympathetic ganglia under normal and pathological states. Quantitative realtime PCR and immunostaining analyses showed that Orai1 and stromal interaction molecules 1 (STIM1) proteins are the primary components of SOCE machinery in the sympathetic ganglia. When the internal Ca²⁺ stores were depleted in the absence of extracellular Ca²⁺, the number of plasmalemmal Orai1 puncta was increased in neurons and SGCs, suggesting activation of the Ca²⁺ entry channels. Intracellular Ca²⁺ imaging revealed that SOCE was present in SGCs and neurons; however, the magnitude of SOCE was much larger in the SGCs than in the neurons. The SOCE was significantly suppressed by GSK7975A, a selective Orai1 blocker, and Pyr6, a SOCE blocker. Lipopolysaccharide (LPS) upregulated the glial fibrillary acidic protein and Toll-like receptor 4 in the sympathetic ganglia. Importantly, LPS attenuated SOCE via downregulating Orai1 and STIM1 expression. In conclusion, sympathetic SGCs functionally express the SOCE machinery, which is indispensable for intracellular Ca²⁺ signaling. The SOCE is highly susceptible to inflammation, which may affect sympathetic neuronal activity and thereby autonomic output.

• The Korean Journal of Physiology
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• v.27 no.2
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• pp.175-183
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• 1993

There are many report suggesting that influx and intracellular calcium concentration $([Ca^{2+}]_i)$ are related to cell signalling in various cells. However, it has not been reported that calcium channel activation is affected by the substances involved in signal transduction pathways in the mouse eggs. In this study, the effects of isoprenaline (ISP) and cyclic AMP on calcium influx through calcium channels were investigated to show their relationship with the signal transduction process in unfertilized mouse eggs. Using whole cell voltage clamp techniques, calcium currents, elicited by the depolarizing pulses of 300 ms duration (from -50 mV to 50 mV in 10 mV increments) from a holding potential of -80 mV, were recorded. The current-voltage (I-V) relation of calcium currents was shown to be bell-shaped; the current began to activate at -50 mV and reached its maximum $(-1.33{\pm}0.16\;nA:\;mean{\pm}S.E.,\;n=7)$ at -10 mV, then decayed at around 50 mV. Calcium currents were fully activated within $7\;ms{\sim}20\;ms$ and completely inactivated 200 ms after onset of the step pulse. ISP within the concentration ranges of $10^{-8}\;M{\sim}10^{-4}\;M$ dose-dependently increased the amplitude calcium current. The permeable cyclic AMP analogue,8-bromocyclic AMP, also increased its maximal amplitude by 46ft at $10^{-5}\;M$, while protein kinase inhibitor (PKI), which is known to inhibit 0.02 phosphorylating units of cyclic AMP-dependent protein kinase (PKA) per microgram decreased calcium currents. Currents recorded in the presence of PKI were resistant to increase by the application of $10^{-5}\;M$. Also, PKI inhibited the calcium current increase elicited by ISP treatment. These results suggest that $\beta-adrenergic$ regulation of the calcium channel is mediated by the cAMP-dependent protein kinase. This signal transduction pathway might play a role in regulating $[Ca^{2+}]_i$, level due to the increase of calcium influx in mouse eggs.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.712-719
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• 1998

Thyroid function is mainly regulated through cAMP and phophatidylinositol, and it is well known that TSH-stimulated thyroxine ($T_4$) release is inhibited by catecholamine from mouse thyroids via the ${\alpha}_1$-adrenoceptor stimulation. Previous study has established that the inhibition of $T_4$ release by ${\alpha}_1$-adrenoceptor stimulation results in activated protein kinase C (PKC). The purpose of this study was to determine if ion transport systems are involved in the inhibition of $T_4$ release elicited by ${\alpha}_1$-adrenergic agonist in mouse thyroids. TSH-, IBMX- and cAMP analogue-stimulated $T_4$ release were significantly inhibited by methoxamine, R59022 (diacylglycerol kinase inhibitor), and MDL (adenylate cyclase inhibitor). TSH-stimulated $T_4$ release could be inhibited by Bay K 8644 and cyclopiazoic acid, but not by verapamil and tetrodotoxin. The addition of nifedipine ($Ca^{2+}$ channel blocker), tetrodotoxin and lidocaine ($Na^+$ channel blockers), but not amiloride (EIPA) and ryanodine, completely blocked the inhibitory effects of methoxamine on $T_4$ release. TSH-stimulated $T_4$ release was also inhibited by benzamil ($Na^+-Ca^{2+}$ exchange inhibitor). TSH-, IBMX- and cAMP-stimulated $T_4$ release were inhibited by methoxamine or R59022, these effects were reversed by nifedipine. but not by verapamil. Furthermore, nifedipine reversed the inhibitory effects of benzamil and R59022 on TSH-stimulated $T_4$ release. These data suggest that the observed ${\alpha}_1$-adrenoceptor-mediated inhibition of $T_4$ release in mouse thyroids is the result of an increase in intracellular $Na^+$ or $Ca^{2+}$ effected via activation of fast $Na^+$ or nifedipine-sensitive $Ca^{2+}$ channels, and that $Na^+-Ca^{2+}$ exchange may play an important role in reducing thyroid hormone by increasing intracellular $Ca^{2+}$.

• Journal of the Ergonomics Society of Korea
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• v.35 no.4
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• pp.205-223
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• 2016

Objective:This study introduced the status of studies and the projects related with agricultural accident prevention carried out by the Rural Development Administration. This study was conducted to promote Korean farmers' agricultural safety activation by analyzing study trends on farmers' agricultural work safety. Background: Agriculture is one of the dangerous industries, and the agricultural accident rate is on the rise, due to recent serious aging and increased female work force. Such a phenomenon emerges as a serious problem from the social perspective, and therefore measures for farmers' healthy and safe agricultural activities and accident prevention are required. Method: This study conducted literature review related with domestic and international agricultural safety and health. This study also examined the hazard factors of agricultural labor and injuries, agricultural safety and health system and policy, support and education for farmers' safety practice, and the status of convenience tools and protection equipment, based on major study activities performed by the Rural Development Administration for recent four to five years. Results: Through the study results, the status of Korea's agricultural safety system, compensation support policy, safety education of farmers for actual practice, and diverse channels including media were confirmed. This study also presented the R&D implementation status on convenience equipment and protective gear to prevent agricultural diseases and safety accidents. Conclusion: This study found out that continuous monitoring and efforts are required to prevent accidents for the Korea's agricultural labor environment and agricultural safety, and that social bond of sympathy formation is demanded through effect analysis on the implemented projects including education and support projects. Furthermore, it can be understood that agricultural accident prevention should be carried out through shift from current government-led top down approach to bottom-up approach from itself. Application: The results of this study can be utilized as useful data for farmers' safety and health.

• 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.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.361-371
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• 2003

The vasorelaxant actions and blood pressure lowering of the ${\alpha}_2$-adrenoceptor agonists (${\alpha}_2$-AAs) clonidine and xylazine were investigated in rat isolated aortic rings and anesthesized rats. Both clonidine and xylazine produced a concentration-dependent inhibition of the sustained contraction induced by norepinephrine (NE), but not by KCl. NE-induced contractions were attenuated partly by nifedipine or verapamil, voltage dependent $Ca^{2+}$ channel blockers. These $Ca^{2+}$ channel blockers-resistant contractions were abolished by clonidine or xylazine. Inhibitory effects of a ${\alpha}_2$-AAs on contractions could be reversed by ryanodine, an intracellular $Ca^{2+}$, transport blocker, and tetrabutylammonium (TBA), a $Ca^{2+}$ activated $K^+$ channel blocker, but not by nifedipine, glibenclamide or removal of extracellular $Ca^{2+}$ and endothelium. Moreover, ${\alpha}_2$-AAs produced relaxation in NE-precontracted isolated intact aortic rings in a concentration-dependent manner, but not in KCl-precontracted rings. The relaxant effects of ${\alpha}_2$-AAs were inhibited by ryanodine and TBA, but not by nifedipine, glibenclamide, N (G)-nitro-L-arginine (L-NNA), N(omega)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine (AG), 2-nitro-4-carboxyphenyl N,N-diphenylcarhurnte (NCDC), lithium sulfate, staurosporine or removal of extracellular $Ca^{2+}$ and endothelium. In vivo, infusion of xylazine elicited significant decrease in anerial blood pressure. This xylazinelowered blood pressure was completely inhibited by the intravenous injection of TBA, but not by the intravenous injection of glibenclamide, L-NNA, L-NAME, AG, nifedipine, lithium sulfate or saponin.. These findings showed that the receptor-mediated and ${\alpha}_2$-adrenoceptor A-stimulated endothelium-independent vasorelaxant effect may be explained by decreasing intracellular $Ca^{2+}$ release and activation of $Ca^{2+}$-activated $K^+$ channels, which may contribute to the hypotensive effects of ${\alpha}_2$-AAs in rats.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.19-29
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• 1996

The neurological manifestations of AIDS include dementia, encountered even in the absence of opportunistic superinfection or malignancy. The AIDS Dementia Complex appears to be associated with several neuropathological abnormalities, including astrogliosis and neuronal injury or loss. How can HIV-1 result in neuronal damage if neurons themselves are only rarely, if ever, infected by the vitus\ulcorner In vitro experiments from several different laboratiories have lent support to the existence of HIV- and immune-related toxins. In one recently defined pathway to neuronal injury, HIV-infected macrophages/microglia as well as macrophages activated by HIV-1 envelope protein gp120 appear to secrete excitants/neurotoxins. These substances may include arachidonic acid, platelet-activating factor, free radicals (NO - and O$_2$), glutamate, quinolinate, cysteine, cytokines (TNF-${\alpha}$, IL1-B, IL-6), and as yet unidentified factors emanating from stimulated macrophages and possibly reactive astrocytes. A final common pathway for newonal suscepubility appears to be operative, similar to that observed in stroke, trauma, epilepsy, and several neurodegenerative diseases, including Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis. This mechanism involves excessive activation of N-methyl-D-aspartate (NMDA) receptor-operated channels, with resultant excessive influx of Ca$\^$2+/ leading to neuronal damage, and thus offers hope for future pharmacological intervention. This chapter reviews two clinically-tolerated NMDA antagonists, memantine and nitroglycerin; (ⅰ) Memantine is an open-channel blocker of the NMDA-associated ion channel and a close congener of the anti-viral and anti-parkinsonian drug amantadine. Memantine blocks the effects of escalating levels of excitotoxins to a greater degree than lower (piysiological) levels of these excitatory amino acids, thus sparing to some extent normal neuronal function. (ⅱ) Niuoglycerin acts at a redox modulatory site of the NMDA receptor/complex to downregulate its activity. The neuroprotective action of nitroglycerin at this site is mediated by n chemical species related to nitric oxide, but in a higher oxidation state, resulting in transfer of an NO group to a critical cysteine on the NMDA receptor. Because of the clinical safety of these drugs, they have the potential for trials in humans. As the structural basis for redox modulation is further elucidated, it may become possible to design even better redox reactive reagents of chinical value. To this end, redox modulatory sites of NMDA receptors have begun to be characterized at a molecular level using site-directed mutagenesis of recombinant subunits (NMDAR1, NMDAR2A-D). Two types of redox modulation can be distinguished. The first type gives rise to a persistent change in the functional activity of the receptor, and we have identified two cysteine residues on the NMDARI subunit (#744 and #798) that are responsible for this action. A second site, presumably also a cysteine(s) because <1 mM N-ethylmaleimide can block its effect in native neurons, underlies the other, more transient redox action. It appears to be at this, as yet unidentified, site on the NMDA receptor that the NO group acts, at least in recombinant receptors.

• Science of Emotion and Sensibility
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• v.14 no.3
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• pp.395-402
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• 2011

As the consumer market for odor products grows, companies producing healthcare products are beginning to pay more attention to the emotional aspect of an odor product in order to differentiate their products from competitors. In the following research, the affective effect of odor product was investigated while focusing on relaxation and working contexts using orange and pine scents, since these are typical odors in current domestic market. Two empirical studies were carried out. First, in experiment I, 18 subjects, all of whom were university students, spent 20 minutes sitting comfortably on a sofa while electrocardiogram assessments were made. After a five-minute break, in experiment II, the same subjects were provided with both arithmetic and geometric questions and their electroencephalogram readings was recorded from eight channels. All subjects participated in three sessions - no odor, an orange scent, and then a pine scent - with a minimum time interval of 24 hours. The results show that in the context of a pine scent, both the activation ratio of subjects' parasympathetic system and those of the Sensory Motor Rhythm waves and Mid Beta waves were at the highest peak. Therefore, the pine scent helped the subjects to feel more comfortable and more focused at the same time. In other words, it gave them a state of meditated attention. In addition, it was found that the right brain was activated twice the intensity when the subjects worked through the geometric questions, whereas both sides of the brain were activated in equal magnitude during the process of arithmetic tasks. This replicates previous studies of the functional aspect of the right brain - being responsible for spatial and creative thinking.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.2
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• pp.87-94
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• 2005

It is not clear whether $Ca^{2+}-induced$ $Ca^{2+}$ release from the sarcoplasmic reticulum (SR) is involved in the regulation of atrial natriuretic peptide (ANP) release. Previously, we have shown that nifedipine increased ANP release, indicating that $Ca^{2+}$ entry via voltage-gated L-type $Ca^{2+}$ channel activation decreases ANP release. The purpose of the present study was two-fold: to define the role of SR $Ca^{2+}$ release in the regulation of ANP release and whether $Ca^{2+}$ entry via L-type $Ca^{2+}$ channel is prerequisite for the SR-related effect on ANP release. Experiments were performed in perfused beating rabbit atria. Ryanodine, an inhibitor of SR $Ca^{2+}$ release, increased atrial myocytic ANP release ($8.69{\pm}3.05$, $19.55{\pm}1.09$, $27.31{\pm}3.51$, and $18.91{\pm}4.76$% for 1, 2, 3, and $6{\mu}M$ ryanodine, respectively; all P<0.01) with concomitant decrease in atrial stroke volume and pulse pressure in a dose-dependent manner. In the presence of thapsigargin, an inhibitor of SR $Ca^{2+}$ pump, ryanodine-induced increase in ANP release was not observed. Thapsigargin attenuated ryanodine-induced decrease in atrial dynamic changes. Blockade of L-type $Ca^{2+}$ channel with nifedipine abolished ryanodine-induced increase in ANP release ($0.69{\pm}5.58$% vs. $27.31{\pm}3.51$%; P＜0.001). In the presence of thapsigargin and ryanodine, nifedipine increased ANP release and decreased atrial dynamics. These data suggest that $Ca^{2+}$-induced $Ca^{2+}$ release from the SR is inversely involved in the regulation of atrial myocytic ANP release.