• 생약학회지
• /
• 제53권2호
• /
• pp.64-69
• /
• 2022

When blood vessels are damaged, a rapid hemostatic response should occur in order to lower blood loss and keep normal circulation, and platelet activation and aggregation are essential. Nevertheless, abnormal or excessive platelet aggregation can be a reason of cardiovascular diseases including thrombosis, atherosclerosis, and stroke. Therefore, the screening for a substance which can regulate platelet activation and suppress aggregation reaction is very important for treatment and prevention of cardiovascular diseases. Artemether is a methyl ether derivative of artemisinin, which is isolated from the antimalarial plant Artemisia annua, but research on platelet aggregation or its mechanisms is still insufficient. This study identified the effects of artemether on U46619-induced human platelet aggregation and their granule secretion (ATP and serotonin release). In addition, the effects of artemether on the phosphorylation of PI3K/Akt or MAPK, which are related to signal transduction in platelet aggregation, were studied. As the results, artemether significantly lowered PI3K/Akt and MAPK phosphorylation, which inhibited platelet aggregation through granule secretion (ATP and serotonin release) dose-dependently. Therefore, we suggest that artemether is an antiplatelet substance that regulates PI3K/Akt and MAPK pathway and is of value as a therapeutic and preventive agent for platelet-derived cardiovascular diseases.

• Biomolecules & Therapeutics
• /
• 제12권1호
• /
• pp.25-33
• /
• 2004

In this study we investigated whether ATP loss was involved in the potentiated death of immunostimulated rat primary astrocytes in glucose-deprived condition. Rat primary astrocytes immunostimulated with LPS plus IFN-${\gamma}$ for 48 h underwent death upon glucose deprivation, which dependent on the production of peroxynitrite. Intracellular ATP level synergistically decreased by glucose deprivation in immunostimulated astrocytes but not in control cells, and the loss of ATP occurred well ahead of the LDH release. The synergistic cell death and ATP loss by immunostimulation and glucose deprivation were inhibited by iNOS inhibitor (L-NAME and L-NNA) or peroxynitrite decomposition catalyst (also a superoxide anion scavenger), Mn(III)tetrakis(N-methyl-4'-pyridyl)porphyrin (MnTMPyP). Exogenous addition of peroxynitrite generator, SIN-l timedependently induced ATP loss and cell death in the glucose-deprived astrocytes. Depletion of intracellular glutathione (GSH) and dis겨ption of mitochondrial transmembrane potential (MTP) were also observed under same conditions. Supply cellular ATP by the addition of exogenous adenosine or ATP during glucose deprivation inhibited ATP depletion, GSH depletion, MTP disruption and cell death in SIN-l treated or immunostimulated astrocytes. This study showed that perturbation in the regulation of intracellular ATP level in immunostimulated astrocytes might make them more vulnerable to energy challenging stimuli.

• The Korean Journal of Physiology and Pharmacology
• /
• 제15권4호
• /
• pp.189-194
• /
• 2011

ATP-sensitive $K^+$ channels ($K_{ATP}$) are major component of preventing ischemia-reperfusion injury. However, there is little information regarding to the expressional difference of $K_{ATP}$ and its function between left and right ventricles. In this study, we measured the lactate dehydrogenase release of rabbit heart slices in vitro and determined the difference of the $K_{ATP}$ expression at the both ventricles by measuring the level of $K_{ATP}$-forming Kir6.2 (OcKir6.2) mRNA using in situ hybridization. The hearts were preconditioned with 15 min hypoxia and reoxygenated for 15 min before a hypoxic period of 60 min, followed by reoxygenation for 180 min. With hypoxic preconditioning (100% $N_2$) with 15 min, left ventricles (LV) showed higher release of LDH comparing with right ventricles (RV). Adding $K_{ATP}$ blocker glibenclamide ($10{\mu}M$) prior to a hypoxic period of 60 min, hypoxic preconditioning effect of RV was more abolished than LV. With in situ hybridization, the optical density of OcKir6.2 was higher in RV. Therefore, we suggest that different $K_{ATP}$ expression between LV and RV is responsible for the different response to hypoxia and hypoxic preconditioning of rabbit hearts.

• 한국식품위생안전성학회지
• /
• 제9권1호
• /
• pp.23-30
• /
• 1994

When three systems commonly used for screening(washed platelets suspended in uffer containing Ca2+, washed platelets in buffer without Ca2+and platelet rich plasma) are compared by studying the anti-aggregating capacity of garlic extract, platelet rich plasma was the least sensitive system. The most sensitive assay system, based on the IC50s of garlic extract and 2 other platelet aggregation-inhibiting agents(vitamin K3 and propranolol), was the platelet preparation without Ca2+in the suspension buffer. This system was confirmed as the most sensitive during subsequent investigation of garlic extract's capacity to inhibit platelet ATP release. These results suggest that applying the system with washed platelet without Ca2+is most effective to screen for the anti-affregating capacity of natural food.

• 한국식품위생안전성학회지
• /
• 제11권4호
• /
• pp.273-276
• /
• 1996

Platelets serve many biological functions, including a major role in the haemostatic process. But platelets also play a crucial role in the formation of arterial thrombosis, arteriosclerosis and other pathologic processes. Thus, there have been many studies to develop new antiplatelet agents from foods and plants for decades. Inthis study, inhibitory effects of the oriental onion (Allium fistulosum) on platelet aggregation were investigated using platelet rich plasma (PRP). Water extracts of oriental onion was separated into two fractions (Fraction I and Fraction II) by Sephadex G-150 column. Platelet aggregations were inhibited by total water extracts as well as Fraction I and II. IC50 value of Fraction I was much lower than that of Fraction II. Inhibitory effects of total water extracts of oriental onion on ATP release by PRP were also observed.

• Animal Bioscience
• /
• 제36권10호
• /
• pp.1604-1611
• /
• 2023

Objective: The aim of this study was to investigate the protective effect of wheat phytase as a structural decomposer of inflammatory nucleotides, extracellular adenosine triphosphate (ATP), and uridine diphosphate (UDP) on HT-29 cells. Methods: Phosphatase activities of wheat phytase against ATP and UDP was investigated in the presence or absence of inhibitors such as L-phenylalanine and L-homoarginine using a Pi Color Lock gold phosphate detection kit. Viability of HT-29 cells exposed to intact- or dephosphorylated-nucleotides was analyzed with an EZ-CYTOX kit. Secretion levels of pro-inflammatory cytokines (IL-6 and IL-8) in HT-29 cells exposed to substrate treated with or without wheat phytase were measured with enzyme-linked immunosorbent assay kits. Activation of caspase-3 in HT-29 cells treated with intact ATP or dephosphorylated-ATP was investigated using a colorimetric assay kit. Results: Wheat phytase dephosphorylated both nucleotides, ATP and UDP, in a dose-dependent manner. Regardless of the presence or absence of enzyme inhibitors (L-phenylalanine and L-homoarginine), wheat phytase dephosphorylated UDP. Only L-phenylalanine inhibited the dephosphorylation of ATP by wheat phytase. However, the level of inhibition was less than 10%. Wheat phytase significantly enhanced the viability of HT-29 cells against ATP- and UDP-induced cytotoxicity. Interleukin (IL)-8 released from HT-29 cells with nucleotides dephosphorylated by wheat phytase was higher than that released from HT-29 cells with intact nucleotides. Moreover, the release of IL-6 was strongly induced from HT-29 cells with UDP dephosphorylated by wheat phytase. HT-29 cells with ATP degraded by wheat phytase showed significantly (13%) lower activity of caspase-3 than HT-29 cells with intact ATP. Conclusion: Wheat phytase can be a candidate for veterinary medicine to prevent cell death in animals. In this context, wheat phytase beyond its nutritional aspects might be a novel and promising tool for promoting growth and function of intestinal epithelial cells under luminal ATP and UDP surge in the gut.

• The Journal of Korean Physical Therapy
• /
• 제14권2호
• /
• pp.1-15
• /
• 2002

Excitation-contraction coupling in skeletal muscle is process by which depolarization of the muscle fiber membrane, elicited by a nerve action potential, triggers the release of $Ca^{2+}$ from the sarcoplasmic reticulum(SR). The resulting rise in intracellular $Ca^{2+}$ concentration$([Ca^{2+}]_i)$ activates the troponin complex, thereby initiating the contraction of the muscle. The question remains as to what factors are involved in the inhibition of SR $Ca^{2+}$ release in fatigued muscle. The purpose of this study was determine whether ATP-sensitive $K^+(K_{ATP})$ channels are activated and contribute to decrease in $[Ca^{2+}]_i$ during fatigue development in the mouse skeletal muscle. To elucidate a role of $K_{ATP})$ in relation to ECC, I measured the modulation effects of $K_{ATP})$ channel blocker(glibenclamide) and opener(pinacidil) on $[Ca^{2+}]_i$ after fatiguing electrical field stimulation(FEFS). Intracellular $Ca^{2+}$ signals were recorded by conforcal laser microscopy(LSM 410) and monitored using the fluorescent $Ca^{2+}$-Sensitive indicator Fluo-3 AM. The results of this study were as followed: 1. The relative [Ca2'li after FEFS in the pre-glibenclamide-treated group was higher than the control. And relative $[Ca^{2+}]_i$ after FEFS in the pre-glibenclamide-treated group was lower than the control. 2. The relative $[Ca^{2+}]_i$ after FEFS for 3 min in the control, pre-glibenclamide-treated group and pre-pinacidil-treated group showed a similar pattern; the gradually significant decrease in $[Ca^{2+}]_i$. But, these decreasing pattern was most significant in the control. These findings suggest a tight relationship between $K_{ATP})$ and $Ca^{2+}$ in ECC during fatigue. Therefore, 1 thought that activation of $K_{ATP})$ channels may be one of mechanisms of the fatigue in skeletal muscle.

• 동의생리병리학회지
• /
• 제19권3호
• /
• pp.743-748
• /
• 2005

This study was performed for the investigation of vasodilatory efficacy and its underlying mechanisms of Jagumhuan(JGH), a herbal remedy. JGH produced completely endothelium-dependent relaxation and relaxed phenylephrine(PE)-precontracted aorta in a concentration dependent manner. The magnitude of relaxation was greater in PE induced contraction than that of KCl, suggesting involvement of $K^+$ channel in the relaxant effect. Both glibenclamide$(10^{-5}M)$, a $K_{ATP}$ channel inhibitor and indometacin, a cyclooxygenase inhibitor, completely prevented this relaxation. The relaxation effects of JGH, involve in part the release of nitric oxide from the endothelium as pretreatment with L-NAME, an NOS inhibitor, and methylene blue, a cGMP inhibitor, attenuated the responses by 62% and 58%, respectively. In addition, nitrite was produced by JGH in human aortic smooth muscle cells and human umbilical vein endothelial cells. The relaxant effect of JGH was also inhibited by 55.41% by tetraethylammonium(TEA; 5mM), a $K_{Ca}$ channel inhibitor. In the absence of extracellular $Ca^{2+}$, pre-incubation of the aortic rings with JGH significantly reduced the contraction by PE, suggesting that the relaxant action of the JGH includes inhibition of $Ca^{2+}$ release from intracellular stores. These results indicate that in rat thoracic aorta, JGH may induce vasodilation through ATP sensitive $K^+$ channel activation by prostacyclin production. However, the relaxant effect of JGH may also mediated in part by NO pathways and $Ca^{2+}$ activated $K^+$ channel.

• Journal of Photoscience
• /
• 제9권2호
• /
• pp.427-429
• /
• 2002

We studied iron release from ferritin by irradiating the visible light, and then followed ferritin-mediated lipid peroxidation in the rod outer segment (ROS) fraction of the porcine retina. In the presence of several phosphorus compounds such as ADP and ATP, iron release from ferritin at pH 7.0 could be induced by irradiation of the visible light to the reaction mixtures. Furthermore, iron release from ferritin in the presence of ADP depended on the incubation time and the visible light irradiation. Moreover, we investigated lipid peroxidation level in the ROS fraction by two independent assay systems including the thiobarbituric acid (TBA) and ferrous oxidation/xylenol orange (FOX) methods. The visible light induced ferritin-mediated lipid peroxidation in the ROS fraction in time- and irradiance-dependent manners. In the dark condition, iron release and lipid peroxidation were not observed. Iron release from ferritin by irradiating the visible light may play an important role in the etiology of phototoxic injuries in vivo.

• 약학회지
• /
• 제43권6호
• /
• pp.851-860
• /
• 1999

The effects of antimycin A(AA), dodium azide ($NaN_3$) and 2,4-dinitrophenol (DNP), which inhibit mitochondrial ATP production, on cellular functions of cultured astrocytes were studied. High concentrations of AA $(50{\;}\mu\textrm{g}/ml),{\;}NaN_3$ (100mM) and DNP (20mM) significantly decreased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction, which was known to be related to mitochondrial function and then cel viability. AA ($50{\;}\mu\textrm{g}/ml$) increased lactate dehydrogenase (LDH) release and decreased [$^3H$] glutamate uptake, suggesting severe damage of cellular function by the concentrations of the compounds. Meanwhile, low concentrations of AA $(\leq{;\}10{\;}\mu\textrm{g}/ml),{\;}NaN_3{;\}(\leq{\;}50mM)$ and DNP ($\leq{\;}5mM$) significantly increased MTT reduction, the effect of which was specific to astrocytes. AA (5 and $10{\;}\mu\textrm{g}/ml$) did not affect LDH release and [$^3H$] glutamate uptake, indicating that these compounds increased MTT reduction at the low concentrations without cellular membrane damage. However, the low concentrations of AA produced significant decrease of MTT reduction in a glucose-free medium. Low concentrations of AA (1 and $5{\;}\mu\textrm{g}/ml$) did not change ATP production of astrocytes in the medium containing 10 mM glucose, but completely inhibited in a glucose-free medium, suggesting marked increase of cytosolic ATP production by the blockade of mitochondrial ATP production with low concentrations of AA. These results suggest that astrocytes have ability to enhance neuronal function or survival under conditions of incomplete ischemia or early by enhancement of glycolysis, and that cellular reduction of MTT occurs not only mitochondrially but also extramitchondrially.