• Archives of Pharmacal Research
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• 제24권6호
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• pp.508-513
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• 2001

2-(1-Hexynyl), 2-((E)-1-hexenyl) and $2-(n-hexyl)-N^{6}$-methyladenines were synthesized, starting from 2-amino-6-chloropurine using palladium-catalyzed coupling as a key step as potential adenosineo receptor ligand.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1998년도 한국생물과학협회 학술발표대회
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• pp.74-74
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• 1998

No Abstract, See Full Text

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1620-1624
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• 2011

Homologated analogues 3a and 3b of potent and selective A3 adenosine receptor ligands, IB-MECA and dimethyl-IB-MECA were synthesized from commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-${\beta}$-D-ribofuranose (4) via $Co_2(CO)_8$-catalyzed siloxymethylation as a key step. Unfortunately, homologated analogues 3a and 3b did not show significant binding affinities at three subtypes of adenosine receptors, indicating that free rotation, resulting from homologation, induced unfavorable interactions in the binding site of the receptor maybe due to the presence of many conformations.

• The Korean Journal of Physiology
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• 제30권1호
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• pp.1-9
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• 1996

The objective of the present study was to characterize the role of adenosine in regulation of ATP-sensitive $K^+\;channel\;(K_{ATP}\;channel)$ activity in isolated rabbit ventricular myocytes using the patch clamp technique. Internal adenosine had little effects on KaTr channel activity. In an outside-out patch with intrapipette GTP and ATP, external adenosine stimulated $K_{ATP}\;channel$ activity. In an inside-out Patch with intrapipette adenosine, ATP reduced $K_{ATP}\;channel$ activity, and GTP stimulated $K_{ATP}\;channel$ activity. Adenosine receptor activation shifted the half-maximal inhibition Of $K_{ATP}\;channel\;from\;70\;to\;241\;{\mu}m$. These results Suggest that activation of adenosine receptors stimulates $K_{ATP}\;channels$ in rabbit ventricular myocytes by reducing the apparent affinity of the channel for ATP. The effect may be important for activating $K_{ATP}\;channels$ during early phase of myocardial ischemia.

• 대한약리학회지
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• 제31권3호
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• pp.333-344
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• 1995

fMLP에 의하여 자극된 중성호성 백혈구에서의 superoxide 생성, myeloperoxidase 유리, 칼슘 동원과 백혈구 부착에 나타내는 adenosine과 $N^6-cyclopentyladenosine$의 효과를 관찰하였다. 또한 이들의 효과를 C5a와 PMA의 자극효과에 대하여 그리고 lipopolysaccharide-primed 중성호성 백혈구의 반응에 대하여 관찰하였다. 이와 함께 adenosine의 억제작용에 있어 cAMP의 관여 여부를 조사하였다. 연구 결과로 부터 fMLP에 의해 자극된 중성호성 백혈구에서의 superoxide 생성, 탈과립과 세포내 칼슘 동원과 백혈구 부착은 adenosine 수용체에 의하여 조절된다고 추정된다. Adenosine은 protein kinase C의 활성화에 따른 백혈구 반응의 자극에 영향을 나타내지 않을 것으로 시사된다. Nonprimed 세포에 비하여, lipopolysaccharide-primed 중성호성 백혈구에서 fMLP에 의한 superoxide 생성은 adenosine의 영향을 적게 받을 것으로 여겨진다. Adenosine 존재하에서 백혈구 반응에 나타내는 theophylline의 억제효과는 세포내 cAMP 축적에 기인할 것으로 추정된다.

• The Korean Journal of Physiology and Pharmacology
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• 제8권2호
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• pp.69-76
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• 2004

A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as $GABA_B$ receptors, group III metabotropic glutamate receptors (mGluRs), adenosine $A_1$ receptors, or adrenaline ${\alpha}2$ receptors, attenuate evoked transmitter release via inhibiting voltage-activated $Ca^{2+}$ currents without affecting voltage-activated $K^+$ currents or inwardly rectifying $K^+$ currents. Furthermore, inhibition of voltage-activated $Ca^{2+}$ currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of $Ca^{2+}$ influx. Direct loadings of G protein ${\beta}{\gamma}$ subunit $(G{\beta}{\gamma})$ into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic $Ca^{2+}$ currents $(Ip_{Ca})$, suggesting that $G{\beta}{\gamma}$ mediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.

• Korean Journal of Anesthesiology
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• 제71권6호
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• pp.476-482
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• 2018

Background: Several types of receptors are found at neuromuscular presynaptic membranes. Presynaptic inhibitory $A_1$ and facilitatory $A_{2A}$ receptors mediate different modulatory functions on acetylcholine release. This study investigated whether adenosine $A_1$ receptor agonist contributes to the first twitch tension (T1) of train-of-four (TOF) stimulation depression and TOF fade during rocuronium-induced neuromuscular blockade, and sugammadex-induced recovery. Methods: Phrenic nerve-diaphragm tissues were obtained from 30 adult Sprague-Dawley rats. Each tissue specimen was randomly allocated to either control group or 2-chloroadenosine (CADO, $10{\mu}M$) group. One hour of reaction time was allowed before initiating main experimental data collection. Loading and boost doses of rocuronium were sequentially administered until > 95% depression of the T1 was achieved. After confirming that there was no T1 twitch tension response, 15 min of resting time was allowed, after which sugammadex was administered. Recovery profiles (T1, TOF ratio [TOFR], and recovery index) were collected for 1 h and compared between groups. Results: There were statistically significant differences on amount of rocuronium (actually used during experiment), TOFR changes during concentration-response of rocuronium (P = 0.04), and recovery profiles (P < 0.01) of CADO group comparing with the control group. However, at the initial phase of this experiment, dose-response of rocuronium in each group demonstrated no statistically significant differences (P = 0.12). Conclusions: The adenosine $A_1$ receptor agonist (CADO) influenced the TOFR and the recovery profile. After activating adenosine receptor, sugammadex-induced recovery from rocuronium-induced neuromuscular block was delayed.

• 대한약리학회지
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• 제19권1호
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• pp.77-84
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• 1983

The behavioral pattern of an animal is influenced by endogenous and endogenous stimuli such as humoral secretion, neurohumoral transmitters, drugs, light and environmental change. It has teen known that adenosine is a normal constituent of brain, and has sedative or hypnotic effects and anticonvulsant effects, inhibiting the spontaneous firing of cells in the brain via membrane adenosine receptors. Recent studies suggest that the excitatory responses to xanthines in the CNS might be related to the competitive antagonism of xanthines to adenosine. This study was undertaken to Investigate the effects of adenosine and the CNS stimulants such as picrotoxin, strychnine and caffeine on the spontaneous activity of mire, and to examine the influence of adenosine on the seizures induced by large doses of CNS stimulants. Subjects were $20{\sim}30\;g$ adult mice, and the spontaneous activity was measured using the Selective Activity Meter after intraperitoneal injection of adenosine (10 mg/kg), caffeine (100 mg/kg), strychnine(0.2 mg/kg) or picrotoxin(0.5 mg/kg) with or without adenosine pretreatment. The seizures were induced with caffeine(200, 250 and 300 mg/kg), strychnine(1.25 and 1.5 mg/kg) or picrotoxin(10 and 15 mg/kg). The results are summarized as follows : 1) The spontaneous activity in mite was significantly inhibited between 10 and 20 minutes after adenosine treatment. 2) Caffeine and picrotoxin increased the motor activity significantly while strychnine had no effect on the activity. 3) The ambulatory activity in the caffeine, strychnine and picrotoxin treated groups was significantly inhibited by adenosine pretreatment. 4) The seizures were observed with caffeine(200, 250 and 300 m9/kg), strychnine(1.25 and 1.5 mg/kg) or picrotoxin(10 and 15 mg/kg). The caffeine induced seizures were inhibited by adenosine pretreatment, but the strychnine or picrotoxin induced seizures were not affected.

• Biomolecules & Therapeutics
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• 제14권2호
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• pp.119-124
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• 2006

This study was performed to investigate the influence of the spinal adenosine $A_1$ receptors on the central regulation of blood pressure (BP) and heart rate (HR), and to define whether its mechanism is mediated by cyclic AMP (cAMP), cyclic GMP (cGMP) or potassium channel. Intrathecal (i.t.) administration of drugs at the thoracic level were performed in anesthetized, artificially ventilated male Sprague-Dawley rats. I.t. injection of adenosine $A_1$ receptor agonist, $N^6$-cyclohexyladenosine (CHA; 1, 5 and 10 nmol) produced dose dependent decrease of BP and HR and it was attenuated by pretreatment of 50 nmol of 8-cyclopentyl-1,3-dimethylxanthine, a specific adenosine $A_1$ receptor antagonist. Pretreatment with a cAMP analogue, 8-bromo-cAMP, also attenuated the depressor and bradycardiac effects of CHA (10 nmol), but not with cGMP analogue, 8-bromo-cGMP. Pretreatment with a ATP-sensitive potassium channel blocker, glipizide (20 nmol) also attenuated the depressor and bradycardiac effects of CHA (10 nmol). These results suggest that adenosine $A_1$ receptor in the spinal cord plays an inhibitory role in the central cardiovascular regulation and that this depressor and bradycardiac actions are mediated by cAMP and potassium channel.

• The Korean Journal of Physiology and Pharmacology
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• 제14권3호
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• pp.145-150
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• 2010

Adenosine (Ado) is an important mediator of the endogenous defense against ischemia-induced injury in the heart. The action of Ado is mediated by activation of G protein-gated inwardly rectifying $K^+$ (GIRK) channels. In turn, GIRK channels are inhibited by reducing phosphatidylinositol 4,5-bisphosphate ($PIP_2$) through Gq protein-coupled receptors (GqPCRs). We previously found that GIRK channels activated by acetylcholine, a muscarinic M2 acetylcholine receptor agonist, are inhibited by GqPCRs in a receptor-specific manner. However, it is not known whether GIRK channels activated by Ado signaling are also regulated by GqPCRs. Presently, this was investigated in mouse atrial myocytes using the patch clamp technique. GIRK channels were activated by $100\;{\mu}M$ Ado. When Ado was repetitively applied at intervals of 5~6 min, the amplitude of second Ado-activated GIRK currents ($I_{K(Ado)}$) was $88.3{\pm}3.7%$ of the first $I_{K(Ado)}$ in the control. Pretreatment of atrial myocytes with phenylephrine, endothelin-1, or bradykinin prior to a second application of Ado reduced the amplitude of the second $I_{K(Ado)}$ to $25.5{\pm}11.6%$, $30.5{\pm}5.6%$, and $96.0{\pm}2.7%$, respectively. The potency of $I_{K(Ado)}$ inhibition by GqPCRs was different with that observed in acetylcholine-activated GIRK currents ($I_{K(ACh)}$) (endothelin-1>phenylephrine>bradykinin). $I_{K(Ado)}$ was almost completely inhibited by $500\;{\mu}M$ of the $PIP_2$ scavenger neomycin, suggesting low $PIP_2$ affinity of $I_{K(Ado)}$. Taken together, these results suggest that the crosstalk between GqPCRs and the Ado-induced signaling pathway is receptor-specific. The differential change in $PIP_2$ affinity of GIRK channels activated by Ado and ACh may underlie, at least in part, their differential responses to GqPCR agonists.