• The Korean Journal of Physiology and Pharmacology
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• v.26 no.2
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• pp.125-133
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• 2022

Carbon monoxide (CO) is a known gaseous bioactive substance found across a wide array of body systems. The administration of low concentrations of CO has been found to exert an anti-inflammatory, anti-apoptotic, anti-hypertensive, and vaso-dilatory effect. To date, however, it has remained unknown whether CO influences atrial natriuretic peptide (ANP) secretion. This study explores the effect of CO on ANP secretion and its associated signaling pathway using isolated beating rat atria. Atrial perfusate was collected for 10 min for use as a control, after which high atrial stretch was induced by increasing the height of the outflow catheter. Carbon monoxide releasing molecule-2 (CORM-2; 10, 50, 100 μM) and hemin (HO-1 inducer; 0.1, 1, 50 μM), but not CORM-3 (10, 50, 100 μM), decreased high stretch-induced ANP secretion. However, zinc porphyrin (HO-1 inhibitor) did not affect ANP secretion. The order of potency for the suppression of ANP secretion was found to be hemin > CORM-2 >> CORM-3. The suppression of ANP secretion by CORM-2 was attenuated by pretreatment with 5-hydroxydecanoic acid, paxilline, and 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one, but not by diltiazem, wortmannin, LY-294002, or NG-nitro-L-arginine methyl ester. Hypoxic conditions attenuated the suppressive effect of CORM-2 on ANP secretion. In sum, these results suggest that CORM-2 suppresses ANP secretion via mitochondrial K_ATP channels and large conductance Ca²⁺-activated K⁺ channels.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.5
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• pp.389-399
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• 2015

Zinc has been considered as a vital constituent of proteins, including enzymes. Mobile reactive zinc ($Zn^{2+}$) is the key form of zinc involved in signal transductions, which are mainly driven by its binding to proteins or the release of zinc from proteins, possibly via a redox switch. There has been growing evidence of zinc's critical role in cell signaling, due to its flexible coordination geometry and rapid shifts in protein conformation to perform biological reactions. The importance and complexity of $Zn^{2+}$ activity has been presumed to parallel the degree of calcium's participation in cellular processes. Whole body and cellular $Zn^{2+}$ levels are largely regulated by metallothioneins (MTs), $Zn^{2+}$ importers (ZIPs), and $Zn^{2+}$ transporters (ZnTs). Numerous proteins involved in signaling pathways, mitochondrial metabolism, and ion channels that play a pivotal role in controlling cardiac contractility are common targets of $Zn^{2+}$. However, these regulatory actions of $Zn^{2+}$ are not limited to the function of the heart, but also extend to numerous other organ systems, such as the central nervous system, immune system, cardiovascular tissue, and secretory glands, such as the pancreas, prostate, and mammary glands. In this review, the regulation of cellular $Zn^{2+}$ levels, $Zn^{2+}$-mediated signal transduction, impacts of $Zn^{2+}$ on ion channels and mitochondrial metabolism, and finally, the implications of $Zn^{2+}$ in health and disease development were outlined to help widen the current understanding of the versatile and complex roles of $Zn^{2+}$.

• Molecules and Cells
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• v.46 no.9
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• pp.545-557
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• 2023

Sphingomyelinase (SMase) catalyzes ceramide production from sphingomyelin. Ceramides are critical in cellular responses such as apoptosis. They enhance mitochondrial outer membrane permeabilization (MOMP) through self-assembly in the mitochondrial outer membrane to form channels that release cytochrome c from intermembrane space (IMS) into the cytosol, triggering caspase-9 activation. However, the SMase involved in MOMP is yet to be identified. Here, we identified a mitochondrial Mg²⁺-independent SMase (mt-iSMase) from rat brain, which was purified 6,130-fold using a Percoll gradient, pulled down with biotinylated sphingomyelin, and subjected to Mono Q anion exchange. A single peak of mt-iSMase activity was eluted at a molecular mass of approximately 65 kDa using Superose 6 gel filtration. The purified enzyme showed optimal activity at pH of 6.5 and was inhibited by dithiothreitol and Mg²⁺, Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Fe²⁺, and Fe³⁺ ions. It was also inhibited by GW4869, which is a non-competitive inhibitor of Mg²⁺-dependent neutral SMase 2 (encoded by SMPD3), that protects against cytochrome c release-mediated cell death. Subfractionation experiments showed that mt-iSMase localizes in the IMS of the mitochondria, implying that mt-iSMase may play a critical role in generating ceramides for MOMP, cytochrome c release, and apoptosis. These data suggest that the purified enzyme in this study is a novel SMase.

• Molecules and Cells
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• v.27 no.3
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• pp.321-327
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• 2009

Voltage-dependent anion channels (VDACs) are reported to be porin-type, ${\beta}$-barrel diffusion pores. They are prominently localized in the outer mitochondrial membrane and are involved in metabolite exchange between the organelle and the cytosol. In this study, we have investigated a family of VDAC isoforms in Arabidopsis thaliana (AtVDAC). We have shown that the heterologous expression of AtVDAC proteins can functionally complement a yeast mutant lacking the endogenous mitochondrial VDAC gene. AtVDACs tagged with GFP were localized to mitochondria in both yeast and plant cells. We also looked at the response of AtVDACs to biotic and abiotic stresses and found that four AtVDAC transcripts were rapidly up-regulated in response to a bacterial pathogen.

• Journal of Ginseng Research
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• v.39 no.4
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• pp.299-303
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• 2015

Panax ginseng is a well-known economic medical plant that is widely used in Chinese traditional medicine. This species contains a unique class of natural products-ginsenosides. Recent clinical and experimental studies have presented numerous lines of evidence on the promising role of ginsenosides on different diseases including neurodegenerative diseases, cardiovascular diseases, and certain types of cancer. Nowadays, most of the attention has focused on ginsenoside Rd as a neuroprotective agent to attenuate ischemic stroke damages. Some of the evidence showed that ginsenoside Rd ameliorates ischemic stroke-induced damages through the suppression of oxidative stress and inflammation. Ginsenoside Rd can prolong neural cells' survival through the upregulation of the endogenous antioxidant system, phosphoinositide-3-kinase/AKT and extracellular signal-regulated protein kinase 1/2 pathways, preservation of mitochondrial membrane potential, suppression of the nuclear factor-kappa B, transient receptor potential melastatin, acid sensing ion channels 1a, poly(ADP-ribose) polymerase-1, protein tyrosine kinase activation, as well as reduction of cytochrome c-releasing and apoptosis-inducing factor. In the current work, we review the available reports on the promising role of ginsenoside Rd on ischemic stroke. We also discuss its chemistry, source, and the molecular mechanism underlying this effect.

• The Journal of Internal Korean Medicine
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• v.24 no.2
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• pp.348-357
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• 2003

Objectives : The purpose of this investigation is to evaluate the effects of Aucklandiae Radix Moschus(木香 麝香)and to study the mechanism for neuronal death protection in hypoxia with Embryonic day 20 (E20) cortical cells of a rat (Sprague Dawley). Methods : E20 cortical cells used in this investigation were dissociated in Neurobasal media and grown for 14 days in vitro (DIV). On 14 DIV, Aucklandiae Radix Moschus(木香 麝香) was added to the culture media for 72 hrs. On 17 DIV, cells were given a hypoxic shock and further incubated in normoxia for another three days. On 20 DIV, Moschus(麝香)'s effects for neuronal death protection were evaluated by LDH assay and the mechanisms were studied by Bcl-2, Bak, Bax, caspase family. Results : This study indicate that Aucklandiae Radix(木香)'s effects for neuronal death protection in normoxia and Scutellariae Radix(麝香)'s effects for neuronal death protection in hypoxia were confirmed by LDH assay in culture method of Embryonic day 20(E20) cortical neuroblast. Moschus(麝香)'s mechanism for neuronal death protection in hypoxia is to increase the anti-apoptosis protein Bcl-2. Conclusions : It may be reasonable to propose that Moschus(麝香) protects delayed neuronal death in hypoxia by increasing Bcl-2, thereby reducing mitochondrial permeability transition(PT) pores, the cytochrome c channels.

• Journal of Ginseng Research
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• v.41 no.1
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• pp.103-112
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• 2017

Background: 20(S)-Protopanaxadiol 20-O-D-glucopyranoside, also called compound K (CK), exerts antidiabetic effects that are mediated by insulin secretion through adenosine triphosphate (ATP)-sensitive potassium ($K_{ATP}$) channels in pancreatic ${\beta}$-cells. However, the antidiabetic effects of CK may be limited because of its low bioavailability. Methods: In this study, we aimed to enhance the antidiabetic activity and lower the toxicity of CK by including it with ${\beta}$-cyclodextrin (CD) (CD-CK), and to determine whether the CD-CK compound enhanced pancreatic islet recovery, compared to CK alone, in an alloxan-induced diabetic zebrafish model. Furthermore, we confirmed the toxicity of CD-CK relative to CK alone by morphological changes, mitochondrial damage, and TdT-UTP nick end labeling (TUNEL) assays, and determined the ratio between the toxic and therapeutic dose for both compounds to verify the relative safety of CK and CD-CK. Results: The CD-CK conjugate ($EC_{50}=2.158{\mu}M$) enhanced the recovery of pancreatic islets, compared to CK alone ($EC_{50}=7.221{\mu}M$), as assessed in alloxan-induced diabetic zebrafish larvae. In addition, CD-CK ($LC_{50} =20.68{\mu}M$) was less toxic than CK alone ($LC_{50}=14.24{\mu}M$). The therapeutic index of CK and CD-CK was 1.98 and 9.58, respectively. Conclusion: The CD-CK inclusion complex enhanced the recovery of damaged pancreatic islets in diabetic zebrafish. The CD-CK inclusion complex has potential as an effective antidiabetic efficacy with lower toxicity.

• The Korean Journal of Pharmacology
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• v.27 no.1
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• pp.45-52
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• 1991

The inhibitory effects of GS354 and GS389 on cytosolic $Ca^{2+}$ level ($[Ca^{2+}]_{1}$; measured with fura-2 fluorescence) and muscle tension in vascular smooth muscle of rat thoracic aorta were investigated. Both GS354 and GS389 inhibited the contractions induced by high $K^+$ or by norepinephrine. The vasodilator effect of GS354 was accompanied by a decrease in $[Ca^{2+}]_{1}$. The inhibitory effect on high $K^+-stimulated$ $[Ca^{2+}]_{1}$ was antagonized by a $Ca^{2+}$ channel activator, Bay K8644. However, the inhibitory effect on muscle tension was not antagonized by Bay K8644. These results suggest that GS354 inhibits $Ca^{2+}$ channels to decrease $[Ca^{2+}]_{1}$ and also decreases $Ca^{2+}$ sensitivity of contractile elements. The inhibitory effects of GS389 was accompanied by the increase in tissue fluorescence. This increment was not due to fura-2 fluorescence but to endogeneous pyridine nucleotides, suggesting that GS389 has an effect to inhibit mitochondrial function. Because of this interference, effects of GS389 on $[Ca^{2+}]_{1}$ was obscured. However, since sequential addition of Bay K8644 in the presence of GS389 further increased the fluorescence but not muscle tension, this compound seems to have the effects to inhibit $Ca^{2+}$ channels and to decrease $Ca^{2+}$ sensitivity of contractile elements.