• The Korean Journal of Physiology and Pharmacology
• /
• 제17권3호
• /
• pp.223-228
• /
• 2013

The calcium-activated $K^+$ ($BK_{Ca}$) channel is one of the potassium-selective ion channels that are present in the nervous and vascular systems. $Ca^{2+}$ is the main regulator of $BK_{Ca}$ channel activation. The $BK_{Ca}$ channel contains two high affinity $Ca^{2+}$ binding sites, namely, regulators of $K^+$ conductance, RCK1 and the $Ca^{2+}$ bowl. Lysophosphatidic acid (LPA, 1-radyl-2-hydroxy-sn-glycero-3-phosphate) is one of the neurolipids. LPA affects diverse cellular functions on many cell types through G protein-coupled LPA receptor subtypes. The activation of LPA receptors induces transient elevation of intracellular $Ca^{2+}$ levels through diverse G proteins such as $G{\alpha}_{q/11}$, $G{\alpha}_i$, $G{\alpha}_{12/13}$, and $G{\alpha}s$ and the related signal transduction pathway. In the present study, we examined LPA effects on $BK_{Ca}$ channel activity expressed in Xenopus oocytes, which are known to endogenously express the LPA receptor. Treatment with LPA induced a large outward current in a reversible and concentration-dependent manner. However, repeated treatment with LPA induced a rapid desensitization, and the LPA receptor antagonist Ki16425 blocked LPA action. LPA-mediated $BK_{Ca}$ channel activation was also attenuated by the PLC inhibitor U-73122, $IP_3$ inhibitor 2-APB, $Ca^{2+}$ chelator BAPTA, or PKC inhibitor calphostin. In addition, mutations in RCK1 and RCK2 also attenuated LPA-mediated $BK_{Ca}$ channel activation. The present study indicates that LPA-mediated activation of the $BK_{Ca}$ channel is achieved through the PLC, $IP_3$, $Ca^{2+}$, and PKC pathway and that LPA-mediated activation of the $BK_{Ca}$ channel could be one of the biological effects of LPA in the nervous and vascular systems.

• 동의생리병리학회지
• /
• 제21권2호
• /
• pp.453-461
• /
• 2007

Drynariae Rhizoma has been used for promotes mending of the sinews and bone, tonifies the kidney for such symptoms as weak low back and knees, and stimulates the growth of hair as a tinctute for alopecia in oriental medicine. This experiment examined the effect of an acetone extracts of Drynariae Rhizomas(GSB-1), its EtoAc fraction(GB-2) and n-buOH fraction(GSB-3), on hair growth activity of the C57BL/6L mice after topical application to skin. First, We examined on hair growth activity of extracts of Drynariae Rhizomas compare to control and 1 % minoxidil groups. Second, We investigated on the number of hair follicle and mast cells after topical application of extracts of the Drynariae Rhizomas to skin for 16 day. Third, We investigated immunoreactive density of vascular endothelial growth factor(VEGF), protein kinase C-${\alpha}$(PKC-${\alpha}$) and stem(mast) cell factor(SCF) in skin of C57BL/6N mice by immunohistochemical methods. The results were as follows : Hair growth effect of acetone extracts of Drynariae Rhizomas, its EtoAc fraction and n-BuOH fraction was observed in 98 %, 96 % and 60 % in hair removed skin area in 16 day respectively, Immunoreactive density of VEGF in skin of GSB-1 group was weakly stained compare to control group in 10 day, But GSB-2 and GSB-3 groups were mildy stained in bulge and root sheath of skin. Immunolocalization of SCF antigens was observed weakly stained density in epidermis, bulge, stem cells and dermal papilla of control gruop. but in experimental group, immunoreactivity of SCF antigens was observed mildly stained density in bulge, epidermis and root sheath of GSB-1 gruop, heavily stained density in epidermis, bulge and root sheath of GSB-2 and GSB-3 groups to the hair removal skin of C57BL/6N mice on day 10. These experiment suggest that acetone extracts of Drynariae Rhizomas and its EtoAc fraction may be used for topical treatment of alopecia areata.

• 사상체질의학회지
• /
• 제15권1호
• /
• pp.72-89
• /
• 2003

To elucidate the neuroprotective effect of Yeoldahanso-tang(YHT) on nerve cells damaged by hypoxia, the cytotoxic effects of exposure to hypoxia were determined by XTT(SODIUM3,3'-{I-[(PHENYLAMINO) CARBONYL]-3,4-TETRAZOLIUM}- BIS (4-METHOXY-6-NITRO) BENZENE SULFONIC ACID HYDRATE), NR(Neutral red), MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and SRB(Sulforhodamin B) asssay. The activity of catalase and SOD(Superoxide dismutase) was measured by spectrophometry, and $TNF-{\alpha}$(Tumor cell necrosis $fector-{\alpha}$) and PKC(Protein kinase C) activity was measured after exposure to hypoxia and treatment of YHTWE. Also the neuroprotective effect of YHTWE was researched for the elucidatioion of neuroprotective mechanism. The results were as follows; 1. Hypoxia decreased cell viability measured by XTT, NR assay when cultured cerebral neurons were exposed to 95% N2/5% CO2 for $2{\sim}26$ minutes in these cultures and YHTWE inhibited the decrease of cell viability. 2. H2O2 treatment decreased cell viability measured by MTT, and SRB assay when cultured cerebral neurons were exposed to 1-80 ${\mu}M$ for 6 hours, but YHTWE inhibited the decrease of cell viability. 3. Hypoxia decreased catalase and SOD activity, and also $TNF-{\alpha}$ and PKC activity in these cultured cerebral neurons, but YHTWE inhibited the decrease of the catalase and SOD activity in these cultures. 4. Hypoxia triggered the apoptosis via caspase activation and internucleosomal DNA fragmentation. Also hypoxia stimulate the release of cytochrome c forom mitochondria. YHTWE inhibited the apoptosis via caspase activation induced by hypoxia. From these results, it can be suggested that brain ischemia model induced hypoxia showed neurotoxicity on cultured mouse cerebral neurons, and the YHTWE has the neuroprotective effect in blocking the neurotoxicity induced by hypoxia in cultured mouse cerebral neurons.

• Journal of Pharmaceutical Investigation
• /
• 제38권5호
• /
• pp.295-302
• /
• 2008

In the present study, we examined the changes of uptake and efflux of taurine under various conditions inducing oxidative stress using rat conditionally immortalized syncytiotrophoblast cell line, TR-TBT cell, as blood-placental barrier in vitro model. In addition, we identified the characteristics of taurine transport in TR-TBT cells including general features, besides effect of calcium ion on taurine transport. Taurine uptake showed time, $Na^+$ and $Cl^-$ dependency, and was decreased by PKC activator in TR-TBT cells. Also, calcium free condition decreased taurine uptake and evoked taurine efflux in the cells. Oxidative stress induced the change of taurine transport in TR-TBT cells, but the changes were different depending on the types of stimulation inducing oxidative stress. The taurine uptake was increased by TNF-$\alpha$, LPS and DEM stimulation but decreased by $H_2O_2$ and NO stimulation. Also, the taurine efflux was regulated by TNF-$\alpha$ stimulation. In conclusion, the taurine transport through the blood-placental barrier was regulated in oxidative stress conditions, and these results demonstrated that oxidative stress affected the taurine supplies to fetus and taurine level of fetus.

• BMB Reports
• /
• 제47권10호
• /
• pp.552-557
• /
• 2014

The main purpose of this study was to investigate whether type 3 muscarinic acetylcholine receptor (M3R) dysfunction induced vascular hyperpermeability. Transwell system analysis showed that M3R inhibition by selective antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) and small interfering RNA both increased endothelial permeability. Using coimmunoprecipitation and Western blot assay, we found that M3R inhibition increased VE-cadherin and ${\beta}$-catenin tyrosine phosphorylation without affecting their expression. Using PTP1B siRNA, we found that PTP1B was required for maintaining VE-cadherin and ${\beta}$-catenin protein dephosphorylation. In addition, 4-DAMP suppressed PTP1B activity by reducing cyclic adenosine monophosphate (cAMP), but not protein kinase $C{\alpha}$ ($PKC{\alpha}$). These data indicate that M3R preserves the endothelial barrier function through a mechanism potentially maintaining PTP1B activity, keeping the adherens junction proteins (AJPs) dephosphorylation.

• Molecules and Cells
• /
• 제38권7호
• /
• pp.616-623
• /
• 2015

P2 receptors are membrane-bound receptors for extracellular nucleotides such as ATP and UTP. P2 receptors have been classified as ligand-gated ion channels or P2X receptors and G protein-coupled P2Y receptors. Recently, purinergic signaling has begun to attract attention as a potential therapeutic target for a variety of diseases especially associated with gastroenterology. This study determined the ATP and UTP-induced receptor signaling mechanism in feline esophageal contraction. Contraction of dispersed feline esophageal smooth muscle cells was measured by scanning micrometry. Phosphorylation of $MLC_{20}$ was determined by western blot analysis. ATP and UTP elicited maximum esophageal contraction at 30 s and $10{\mu}M$ concentration. Contraction of dispersed cells treated with $10{\mu}M$ ATP was inhibited by nifedipine. However, contraction induced by $0.1{\mu}M$ ATP, $0.1{\mu}M$ UTP and $10{\mu}M$ UTP was decreased by U73122, chelerythrine, ML-9, PTX and $GDP{\beta}S$. Contraction induced by $0.1{\mu}M$ ATP and UTP was inhibited by $G{\alpha}i_3$ or $G{\alpha}q$ antibodies and by $PLC{\beta}_1$ or $PLC{\beta}_3$ antibodies. Phosphorylated $MLC_{20}$ was increased by ATP and UTP treatment. In conclusion, esophageal contraction induced by ATP and UTP was preferentially mediated by P2Y receptors coupled to $G{\alpha}i_3$ and $G{\alpha}q$ proteins, which activate $PLC{\beta}_1$ and $PLC{\beta}_3$. Subsequently, increased intracellular $Ca^{2+}$ and activated PKC triggered stimulation of MLC kinase and inhibition of MLC phosphatase. Finally, increased $pMLC_{20}$ generated esophageal contraction.

• 대한의생명과학회지
• /
• 제22권2호
• /
• pp.60-64
• /
• 2016

In the pathogenesis of inflammatory diseases such as allergies, S100A8 acts as an important molecule and T lymphocytes are essential cytokine-releasing cells. In this study, we investigated the effect of S100A8 on release of cytokines, specifically MCP-1, IL-6, and IL-8 in T cells, and its associated signaling mechanism. S100A8 increased secretion of MCP-1, IL-6, and IL-8 in a time- and dose-dependent manner. Elevated secretion of MCP-1, IL-6, and IL-8 due to S100A8 was inhibited by the TLR4 inhibitor TLR4i, the PI3K inhibitor LY294002, the $PKC{\delta}$ inhibitor rottlerin, the ERK inhibitor PD98059, the p38 MAPK inhibitor SB202190, the JNK inhibitor SP600125, and the NF-${\kappa}B$ inhibitor BAY-11-7085. S100A8 induced phosphorylation of ERK, p38 MAPK, and JNK in a time-dependent manner, and activation was suppressed by TLR4i, LY294002, and rottlerin. S100A8 induced NF-${\kappa}B$ activation by $I{\kappa}-B{\alpha}$ degradation, and NF-${\kappa}B$ activity was suppressed by PD98059, SB202190, and SP600125. These results indicate that S100A8 induces cytokine release via TLR4. Study of PI3K, $PKC{\delta}$, MAPKs, and NF-${\kappa}B$ will contribute to elucidation of the S100A8-invovled mechanism.

• The Korean Journal of Physiology and Pharmacology
• /
• 제20권6호
• /
• pp.581-593
• /
• 2016

The advantages of monounsaturated fatty acids (MUFAs) on insulin resistance and type 2 diabetes mellitus (T2DM) have been well established. However, the molecular mechanisms of the anti-diabetic action of MUFAs remain unclear. This study examined the anti-hyperglycemic effect and explored the molecular mechanisms involved in the actions of fish oil- rich in MUFAs that had been acquired from hybrid catfish (Pangasius larnaudii${\times}$Pangasianodon hypophthalmus) among experimental type 2 diabetic rats. Diabetic rats that were fed with fish oil (500 and 1,000 mg/kg BW) for 12 weeks significantly reduced the fasting plasma glucose levels without increasing the plasma insulin levels. The diminishing levels of plasma lipids and the muscle triglyceride accumulation as well as the plasma leptin levels were identified in T2DM rats, which had been administrated with fish oil. Notably, the plasma adiponectin levels increased among these rats. The fish oil supplementation also improved glucose tolerance, insulin sensitivity and pancreatic histological changes. Moreover, the supplementation of fish oil improved insulin signaling ($p-Akt^{Ser473}$ and p-PKC-${\zeta}/{\lambda}^{Thr410/403}$), $p-AMPK^{Thr172}$ and membrane GLUT4 protein expressions, whereas the protein expressions of pro-inflammatory cytokines (TNF-${\alpha}$ and nuclear NF-${\kappa}B$) as well as p-PKC-${\theta}^{Thr538}$ were down regulated in the skeletal muscle. These data indicate that the effects of fish oil-rich in MUFAs in these T2DM rats were partly due to the attenuation of insulin resistance and an improvement in the adipokine imbalance. The mechanisms of the anti-hyperglycemic effect are involved in the improvement of insulin signaling, AMPK activation, GLUT4 translocation and suppression of pro-inflammatory cytokine protein expressions.

• The Korean Journal of Physiology and Pharmacology
• /
• 제21권6호
• /
• pp.687-694
• /
• 2017

Plumbagin, a hydroxy 1,4-naphthoquinone compound from plant metabolites, exhibits anticancer, antibacterial, and antifungal activities via modulating various signaling molecules. However, its effects on vascular functions are rarely studied except in pulmonary and coronary arteries where NADPH oxidase (NOX) inhibition was suggested as a mechanism. Here we investigate the effects of plumbagin on the contractility of skeletal artery (deep femoral artery, DFA), mesenteric artery (MA) and renal artery (RA) in rats. Although plumbagin alone had no effect on the isometric tone of DFA, $1{\mu}M$ phenylephrine (PhE)-induced partial contraction was largely augmented by plumbagin (${\Delta}T_{Plum}$, 125% of 80 mM KCl-induced contraction at $1{\mu}M$). With relatively higher concentrations (>$5{\mu}M$), plumbagin induced a transient contraction followed by tonic relaxation of DFA. Similar biphasic augmentation of the PhE-induced contraction was observed in MA and RA. VAS2870 and GKT137831, specific NOX4 inhibitors, neither mimicked nor inhibited ${\Delta}T_{Plum}$ in DFA. Also, pretreatment with tiron or catalase did not affect ${\Delta}T_{Plum}$ of DFA. Under the inhibition of PhE-contraction with L-type $Ca^{2+}$ channel blocker (nifedipine, $1{\mu}M$), plumbagin still induced tonic contraction, suggesting $Ca^{2+}$-sensitization mechanism of smooth muscle. Although ${\Delta}T_{Plum}$ was consistently observed under pretreatment with Rho A-kinase inhibitor (Y27632, $1{\mu}M$), a PKC inhibitor (GF 109203X, $10{\mu}M$) largely suppressed ${\Delta}T_{Plum}$. Taken together, it is suggested that plumbagin facilitates the PKC activation in the presence of vasoactive agonists in skeletal arteries. The biphasic contractile effects on the systemic arteries should be considered in the pharmacological studies of plumbagin and 1,4-naphthoquinones.

• 대한수의학회지
• /
• 제35권2호
• /
• pp.229-236
• /
• 1995

The effect of ${\alpha}_1$-adrenoceptor(${\alpha}_1$-AR) stimulation on intracellular pH($pH_i$), $Na^+$ activity($a_{Na}{^i}$) and contractility were investigated in isolated papillary muscles of euthyroid or hyperthyroid guinea pig with conventional microelectrode, $Na^+$ or $H^+$-selective microelectrodes, and tension transducer. Stimulation of the ${\alpha}_1$-AR by phenylephrine produced a decrease in $a_{Na}{^i}$ in euthyroid preparations. This decrease in $a_{Na}{^i}$ was abolished in presence of PKC activator, phorbol dibutyrate, and increased contrary to decrease. Phenylephrine also increased $a_{Na}{^i}$ in hyperthyroid ones. However, phenylrephtine produced an increase in $pH_i$ in both euthyroid and hyperthyroid ones. These changes were blocked by prazosin, an antagonist of ${\alpha}_1$-AR. These findings suggest that the changes in $a_{Na}{^i}$ and $pH_i$ are mediated by a stimulation of $Na^+-H^+$ exchange via ${\alpha}_1$-AR stimulation. This study focused on the increase in $a_{Na}{^i}$, $pH_i$ and contractility. The increase in $pH_i$ was blocked by amiloride or EIPA, $Na^+-H^+$ exchange inhibitors. Therefore, the increase in $a_{Na}{^i}$ and $pH_i$ mediated by ${\alpha}_1$-AR appeared to be due to an influx of $Na^+$ and a reduction of $H^+$ through $Na^+-H^+$ exchange. This study also revealed that the increase in $pH_i$ and $a_{Na}{^i}$ might be related to the sustained positive inotropic response. The $a_{Na}{^i}$ increase may contribute to the intracellular $Ca^{2+}$ through the $Na^+-Ca^{2+}$ exchange, and the $pH_i$ increase could cause an increase in the $Ca^{2+}$ sensitivity of myofilaments and may augment the ${\alpha}_1$-AR-mediated positive inotropic response.