• The Korean Journal of Physiology and Pharmacology
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• v.11 no.5
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• pp.197-206
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• 2007

The aim of the present study was to investigate the effects of 6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine(SKF81297), a selective agonist of dopaminergic $D_1$ receptor, on the secretion of catecholamines(CA) evoked by cholinergic stimulation and membrane-depolarization in the isolated perfused rat adrenal gland, and also to elucidate the mechanism involved. SKF81297($10{\sim}100{\mu}M$) perfused into an adrenal vein for 60 min produced dose- and time-dependent inhibition of CA secretory responses evoked by ACh(5.32 mM), high $K^+$(56 mM), DMPP($100{\mu}M$) and McN-A-343($100{\mu}M$). Also, in adrenal glands loaded with SKF81297($30{\mu}M$), the CA secretory responses evoked by Bay-K-8644($10{\mu}M$), an activator of L-type $Ca^{2+}$ channels and cyclopiazonic acid($10{\mu}M$), an inhibitor of cytoplasmic $Ca^{2+}$-ATPase were also inhibited. However, in the presence of the dopamine $D_1$ receptor antagonist, (R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-benzazepine-7-ol(SCH23390, $3{\mu}M$), which is a selective antagonist of dopaminergic $D_1$ receptor, the inhibitory responses of SKF81297($30{\mu}M$) on the CA secretion evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644, and cyclopiazonic acid were significantly reduced. Collectively, these experimental results suggest that SKF81297 inhibits the CA secretion from the rat adrenal medulla evoked by cholinergic stimulation(both nicotininc and muscarinic receptors) and membrane depolarization. This inhibitory of SKF81297 seems to be mediated by stimulation of dopaminergic $D_1$ receptors located on the rat adrenomedullary chromaffin cells, which are relevant to extra- and intracellular calcium mobilization. Therefore, it is thought that the presence of the dopaminergic $D_1$ receptors may be involved in regulation of CA release in the rat adrenal medulla.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.6
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• pp.1860-1868
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• 2004

Geijibokryunghwan has a wide range of therapeutic applications, and some reports have indicated that it has protective activity against atherosclerosis, and more specifically stroke and myocardial infarction. A recent report showed that atherosclerotic plaque volume can be reduced by supplying Geijibokryunghwan extracts for several years. In this study, we used a component of Geijibokryunghwan, which has been used for the prevention of atherosclerosis in Korea for several years, and has proven to be useful in lowering the occurrence of cerebral infarction. In a preliminary study, we found that Geijibokryunghwan potently suppressed platelet aggregation induced by various agonists. In this study, we sought to explore the mechanism by which Geijibokryunghwan inhibits platelet aggregations.

• The Korean Journal of Pharmacology
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• v.26 no.1
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• pp.55-66
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• 1990

In both resting and opsonized zymosan activated neutrophils, ATP stimulated superoxide generation, whereas adenosine inhibited it slightly. The superoxide generation in activated neutrophils to ATP was greater than that of resting neutrophils. In $Ca^{++}$ free medium, inhibitory effect of adenosine on superoxide generation was detectable, whereas ATP did not have any effect. The stimulatory effect of ATP on superoxide generation was inhibited by adenosine in a dose dependent manner. Neither ATP nor adenosine had any effect on NADPH oxidase acitivity. Effects of ATP or adenosine on superoxide generation were more prominent than that by other triphosphate nucleotides or nucleosides. ATP and ADP further stimulated $Ca^{++}$ uptake and increased cytosolic free $Ca^{++}$ level in neutrophils activated by opsonized zymosan, but adenosine inhibited a $Ca^{++}$ mobilization. Verapamil effectively and tetrodotoxin slightly inhibited an increase of cytosolic free $Ca^{++}$ level induced by ATP. Inhibitory effect of either verapamil or tetrodotoxin on superoxide generation in the ATP plus opsonized zymosan-activated neutrophils was greater than in the cells activated by opsonized zymosan alone. Tetraethylammonium chloride had no apparent effect on superoxide generation. CCCP, 2,4-dinitrophenol, diphenylhydantoin and procaine all inhibited superoxide generation in neutrophils activated by opsonized zymosan. Among these, CCCP only inhibited a stimulatory effect of ATP. ATP further stimulated a loss of sulfhydryl groups in activated neutrophils, whereas adenosine had no effect on it. These results suggest that functional responses of neutrophils may be regulated at least partly by purines. ATP and adenosine may further after functional responses of activated neutrophils through their effect on $Ca^{++}$ uptake, membrane phosphorylation and oxidation of soluble sulfhydryl groups.

• Journal of Ginseng Research
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• v.21 no.2
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• pp.132-140
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• 1997

The effects of ginsenosides purified from red ginseng on platelet aggregation were investigated. Preincubation of washed platelets from rats with either ginsenoside Rg3, ginsenosides non-polar fraction (G-NPF), ginsenoside Rg1(Rg1) or ginsenosides polar fraction(G-PF) reduced the plytelet aggrelation induced by collagen in a dose-dependent manner, whereas ginsenoside Rg2 failed to inhibit the aggregation. Their IC50 values of Rg3, G-NPF, Rgl, and G-PF were 8.7$\pm$1.0, 150.3$\pm$0.1, 369.9$\pm$ 1.0, 606.211.3 $\mu\textrm{g}$/ml, respectively. Aggrelation induced by thrombin was also inhibited by Rg3 and G-NPF with IC50 being 5.2$\pm$ 1.1 and 66.5$\pm$0.8 $\mu\textrm{g}$/ml, respectively. The alterations of Intracellular Ca2+ concentration in platelets were monitored using fura-2 as a fluorescent Ca2+ indicator. Both Ca2+ release from internal stores and Ca2+ influx into cytosol were suppressed by Rg3. Rg3 also inhibited granular release of ATP and TXA2 formation induced by thrombin in a dose-dependent manner in the washed platelets. Rg3 also inhibited Aggregation and ATP release from human platelets induced by collagen to a similar extent as were observed in rat platelets. In conclusion, Rg3 is a Potent anti-aggregating component in ginsenosides and may exert its anti-aggrega1ing activity by decreasing TXAa formation and granular secretion in platelets, most likely by inhibiting Ca2+ influx and Ca2+ mobilization from intracellular stores. Thus ginseng may contribute to the prevention and treatment of thrombosis.

• Biomedical Science Letters
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• v.29 no.4
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• pp.242-248
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• 2023

Platelets are activated at the sites of vascular injury by a number of molecules, including adenosine diphosphate, collagen and thrombin. The full platelet aggregation is absolutely essential for the normal hemostasis. Glycyrrhiza glabra is a well-known medicinal herb that grows in various parts of the world and is known to have various effects such as antioxidant, anti-inflammatory, anti-atherogenic, anti-osteoporotic and skin-whitening. However, the platelet inhibitory effect of Glycyrrhiza glabra extract (GGE) has not been identified. In this study, we investigated if GGE inhibited platelet aggregation. We observed that GGE inhibited collagen-induced platelet aggregation, Ca²⁺ mobilization, and thromboxane A2 generation. In addition, GGE suppressed phosphorylation of phosphatidylinositol-3 kinase (PI3K), Akt and elevated phosphorylation of inositol 1,4,5-trisphosphate receptor (IP3R), vasodilator stimulated phosphoprotein (VASP). Taken together, GGE showed strong antiplatelet effects and may be used to block platelet-mediated cardiovascular diseases.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.1
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• pp.63-68
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• 1998

Nitric oxide (NO)-mediated relaxation in vascular smooth muscle involves not only activation of guanylate cyclase but also hyperpolarization of the membrane. It has been shown that depolarization decreases the [$Ca^{2+}$] sensitivity of myosin light chain kinase in arterial smooth muscle, and nitric oxide (NO)-mediated relaxation was attenuated in this situation. However, why potassium inhibits or attenuates the action of EDRF/NO is not clear. Therefore, we investigated the magnitude of relaxation and cGMP contents using measures known to release NO, such as photorelaxation, photo activated NO-mediated relaxation, and NO-donor (SNP)-mediated relaxation in porcine coronary arterial rings in which contractile conditions were made by different degree of depolarization, i.e., contraction in response to U46619 or U46619 plus KCl. In all cases, the magnitude of relaxation was significantly greater (P＜0.05) in U46619-contracted rings than in U46619+KCl-contracted ones. Although accumulation of cGMP was evident with three measures employed in the present study, no difference was found in cGMP contents between U46619 and U46619+KCl conditions, indicating that the diminished relaxation in KCl containing solution is cGMP-independent mechanism(s). To understand this further, cytosolic $Ca^{2+}$ changes due to NO were compared in rat thoracic aorta by exploiting photoactivated NO using streptozotocin (STZ) that was contracted with either NE or KCl. Fura-3 $[Ca]_{cyt}$ signal caused by NO was small and transient in high $K^+$-, but large and sustained in NE-contracted aorta. The inhibitory potency of STZ expressed in terms of $IC_{50}$ was 5.14 and 3.88 ${\mu}M$ in NE and in high $K^+$, respectively. These results suggest that modification of the cellular mobilization of $Ca^{2+}$ rather than cGMP levels may be an important mechanism for the NO-mediated relaxation when vascular membrane is depolarized, such as atherosclerosis and hypertension.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.629-639
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• 2016

The present study was designed to investigate the characteristics of gintonin, one of components isolated from Korean Ginseng on secretion of catecholamines (CA) from the isolated perfused model of rat adrenal gland and to clarify its mechanism of action. Gintonin (1 to $30{\mu}g/ml$), perfused into an adrenal vein, markedly increased the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. The gintonin-evoked CA secretion was greatly inhibited in the presence of chlorisondamine ($1{\mu}M$, an autonomic ganglionic bloker), pirenzepine ($2{\mu}M$, a muscarinic $M_1$ receptor antagonist), Ki14625 ($10{\mu}M$, an $LPA_{1/3}$ receptor antagonist), amiloride (1 mM, an inhibitor of $Na^+/Ca^{2+}$ exchanger), a nicardipine ($1{\mu}M$, a voltage-dependent $Ca^{2+}$ channel blocker), TMB-8 ($1{\mu}M$, an intracellular $Ca^{2+}$ antagonist), and perfusion of $Ca^{2+}$-free Krebs solution with 5mM EGTA (a $Ca^{2+}$chelater), while was not affected by sodium nitroprusside ($100{\mu}M$, a nitrosovasodialtor). Interestingly, LPA ($0.3{\sim}3{\mu}M$, an LPA receptor agonist) also dose-dependently enhanced the CA secretion from the adrenal medulla, but this facilitatory effect of LPA was greatly inhibited in the presence of Ki 14625 ($10{\mu}M$). Moreover, acetylcholine (AC)-evoked CA secretion was greatly potentiated during the perfusion of gintonin ($3{\mu}g/ml$). Taken together, these results demonstrate the first evidence that gintonin increases the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. This facilitatory effect of gintonin seems to be associated with activation of LPA- and cholinergic-receptors, which are relevant to the cytoplasmic $Ca^{2+}$ increase by stimulation of the $Ca^{2+}$ influx as well as by the inhibition of $Ca^{2+}$ uptake into the cytoplasmic $Ca^{2+}$ stores, without the increased nitric oxide (NO). Based on these results, it is thought that gintonin, one of ginseng components, can elevate the CA secretion from adrenal medulla by regulating the $Ca^{2+}$ mobilization for exocytosis, suggesting facilitation of cardiovascular system. Also, these findings show that gintonin might be at least one of ginseng-induced hypertensive components.

• Korean Journal of Pharmacognosy
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• v.52 no.1
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• pp.26-33
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• 2021

During blood vessel damage, an essential step in the hemostatic process is platelet activation. However, it is important to properly control platelet activation, as various cardiovascular diseases, such as stroke, atherosclerosis, and myocardial infarction, are also caused by excessive platelet activation. Found primarily in the roots of plants of the genus Artemisia or Scopolia, isoscopoletin has been studied to demonstrate its potential pharmacological effects against Alzheimer's disease and anticancer, but the mechanisms and roles involved in thrombus formation and platelet aggregation are insufficient. This study investigated the effect of isoscopoletin on U46619-induced human platelet activation. As a result, isoscopoletin significantly increased the levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) dose-dependently. In addition, isoscopoletin significantly phosphorylated inositol 1, 4, 5-triphosphate receptor (IP3R) and vasodilator-stimulated phosphprotein (VASP), which are known substrates for cAMP-dependent kinases and cGMP-dependent kinases. Phosphorylated IP3R by isoscopoletin inhibited Ca2+ mobilization from the dense tubular system Ca2+ channels to cytosol, and phosphorylated VASP was involved in the inhibition of fibrinogen binding through αIIb/β3 inactivation in the platelet membrane. Isoscopoletin finally reduced thrombin-induced fibrin clotting production. Therefore, this study suggests that isoscopoletin has a potent antiplatelet effect and may be helpful for platelet-related thrombotic diseases.

• Biomolecules & Therapeutics
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• v.8 no.4
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• pp.338-348
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• 2000

The present study was attempted to determine the effect of 5'-(N'-ethylcarboxamido) adenosine (NECA), which is an potent $A_2$-adenosine receptor agonist, on catecholamine (CA) secretion evoked by cholinergic stimulation, membrane depolarization and calcium mobilization from the isolated perfused rat adrenal gland. NECA (20 nM) perfused into the adrenal vein for 60 min produced a time-related inhibition in CA secretion evoked by ACh (5.32x10$^{-3}$ M), high $K^{+}$(5.6x10$^{-2}$ M), DMPP (10$^{-4}$ M for 2 min), McN-A-343 (10$^{-4}$ M for 2 min), cyclopiazonic acid (10$^{-5}$ M for 4 min) and Bay-K-8644 (10$^{-5}$ M for 4 min). Also, in the presence of $\beta$,${\gamma}$-methylene adenosine-5'-triphosphate (MATP), which is also known to be a selective $P_{2x}$-purinergic receptor agonist, showed a similar inhibition elf CA release evoked by ACh, high potassium, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid. However, in adrenal glands preloaded with 20$\mu$M NECA for 20 min under the presence of 20$\mu$M 3-isobutyl-1-methyl-xanthine (IBMX), an adenosine receptors antagonist, CA secretory responses evoked by ACh, high potassium, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were much recovered in comparison to the case of NECA-treatment only. Taken together, these results indicate that NECA causes the marked inhibition of CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors as well as by membrane depolarization. This inhibitory effect may be mediated by inhibiting influx of extracellular calcium and release in intracellular calcium in the rat adrenomedullary chromaffin cells through the adenosine receptor stimulation. Therefore, it is suggested that the inhibitory mechanism of adenosine receptor stimulation may play a modulatory role in regulating CA secretion.n.n.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.634-640
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• 2015

Chelating agents have been proposed to improve the efficiency of phytoextraction of heavy metal hyperaccumulator. However, little studies to elucidate mechanism of chelating agents to increase cadmium (Cd) extractability have been conducted. The objectives of this study were to evaluate effect of different chelating agents on Cd extractability and to determine mechanism of Cd mobilization affected by these agents. An arable soil was spiked with inorganic Cd ($CdCl_2$) to give a total Cd concentration of $20mgCdkg^{-1}$. Ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) were selected and mixed with the arable soil at the rates of 0 and $5mmolkg^{-1}$. The mixture soils were incubated at $25^{\circ}C$ for 4 weeks in dark condition. Concentration of F1 Cd fractions (water soluble) significantly increased with addition of EDTA but did not changed with addition of CA. Especially; concentration of F5 Cd fractions (residual) significantly increased with addition of CA. Increase in water soluble with EDTA might be attributed to complexation of Cd and EDTA. Dissolved organic carbon concentration significantly increased with EDTA addition, but did not with CA implying that considerable amount of CA was decomposed to inorganic carbon by microorganism. Log activity of carbonate ($CO_3{^{2-}}$) which might be generated from CA increased with addition of CA. Increase in residual Cd fraction might be due to precipitation of Cd as $CdCO_3$. As a result, EDTA was effective in increasing Cd extractability, by contrast CA had significant effect in reducing Cd extractability.