• The Korean Journal of Physiology and Pharmacology
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• v.1 no.3
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• pp.325-335
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• 1997

Evidence for the existance of at least two subclasses of renal adenosine receptors has been presented. N-6-cyclohexyladenosine (CHA) is a relatively selective $A_1$ adenosine agonists, whereas 5'-N-ethylcarboxamidoadenosine (NECA) acts as a preferential agonist of $A_2$ adenoisne receptor. N6-(L-2-phenylisoproryl)-adenosine (PIA) almost unselectively activates both $A_1\;and\;A_2$ adenosine receptors at micromolar concentrations. During the characterization of adenosine receptor in the kidney, we have discovered a novel phenomenon, that is, an intramuscular administration of CHA for 3 days caused a diuresis and a suppression of urinary concentrating ability. To further characterize this novel phenomenon, an intramuscular administration of adenosine and other adenosine angonists, PIA and NECA, and prior treatment of adenosine antagonists, caffeine, theophylline and 1,3-diethyl-8-phenyl-xanthine (DPX) were performed. Systemic administration of CHA, PIA, and NECA for 3 days caused a suppression in heart rate, blood pressure and general motor activity without change in rectal temperature. Systemic administration of CHA, 0.5, 1 and 2 mg/kg/day, for 3 days caused a dose-dependent increase in urine volume and decrease in urinary osmolarity and free water reabsorption. This phenomenon was reversible and repeatable. Administration of adenosine (40 mg/kg/day) produced no apparent effect on the renal function, whereas PIA (2 mg/kg/day) produced an similar effect to CHA on the renal function. Systemic adminstration of NECA, 0.025, 0.05 and 0.25 mg/kg/day, for 3 days caused a dose-dependent increase in urine volume and dose-dependent increases in excreted amount of creatinine, urinary osmolarity and free water reabsorption. These renal effects of adenosine agonist were maximum at second day during the drug administration. In terms of increase in urine volume and the suppression of urinary concentrating ability, NECA was potent than CHA. Prior treatment of caffeine (50 mg/kg/day) or theophylline (50 mg/kg/day) abolished the diuretic effect of CHA, whereas DPX (50 mg/kg/day) did not affect the CHA effect. CHA, 0.5 mg/kg/day, produced no change in plasma renin activity and plasma levels of aldosterone, epinephrine, and norepinephrine. These results suggest that this novel phenomenon produced by an activation of renal adenosine receptors plays an important role in urinary concentrating mechanism.

• Korean Journal of Animal Reproduction
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• v.16 no.4
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• pp.387-397
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• 1993

To examine local response of adenosie(purine nucleoside) on the developing mammary gland, Elvax 40P implants containing adenosine were surgically implanted into mammary fat pad of the five week old female ICR mice. Inguinal(the 4th) mammary glands of anesthetized mice were exposed andplaced the implants for 12 days. One gland was treated with an adenosine implant, while the contralateral gland received a blank implant as control. For whole-mount preparations, glands were stained with alum carmine, and for histological observation, micro-selected mammary glands were stained with hematoxylin and eosin Y. Implantation with Elvax 40P did not affect on the damage of neighboring mammary tissue. Adenosie 25 or 250$\mu\textrm{g}$ per slow-release implant stimulated local mammary end bud formation of ovariectomized mice such as end bud size and numbers of end bud per gland in a dose dependent manner(P<0.05), and lower concentration of adenosie(2.5 or 25$\mu\textrm{g}$/implant) increased numbers of end bud(P<0.05) and end bud size(P<0.1) of intact mice. Adenosine treatment and intact ovarian function had moderate interation effects on the stimulation of end bud formation at 2.5$\mu\textrm{g}$ adenosine/implant(P<0.1). In histological observation, adenosine implants increased numbers of mammary epithelial type of cells at mammary duct in the presence or absece ofovary. These results indicate that adenosine should be one of regulators in mouse mammary ductal growth.

• Korean Journal of Microbiology
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• v.31 no.1
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• pp.54-62
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• 1993

Intracellular adenosine deaminase (ADA) from Aspergillus oryzae was purified using ammonium sulfate fractionation, a DEAE-Sephadex A-50 anion exchange chromatography, an ultrafiltration using a PM 10 membrane and two times of Sephadex G-100 gel filtration chromatography. The enzyme was purified 151 fold with a 9% recovery. Purified enzyme gave a single protein band with a molecular weight of 105,000 delton. The enzyme was reasonably stable. The enzyme activity was kept even after 1 hr incubation at 55.deg.C, but decreased significantly at 60.deg.C. The pH optimum was found to be from 6.5 to 7.5. Among tested compounds, the substrate activity was found with adenosine, adenine arainofuranoside, formymcin A, 2'-deoxyadenosine, 3'-deoxyadenosine, 2', 3'-isopropylidene adenosine, 2,6-diaminopurine deoxyriboside, .betha.-nicotinamide adenine dinucleotide (reduced form), 6-chloropurine riboside, 2'-adenine monophosphate (AMP), 3'-AMP and 5'-AMP. The values of Km of adenosine and 2'-deoxyadenosine were calculated to be 500 and .$710\mu$m, respectively. ADA was sensitivite to $Zn^{2+}$, $^Cu{2+}$ and $Fe^{3+}$, p-chloromercuribenzoate and mersalyl acid inactivated the enzyme. The activity of enzyme was not changed when ADA was incubated with dithiothreititol, 2-mercaptoethanol, N-ethylmaleimide, iodoacetic acid and iodoacetamide.

• The Korean Journal of Physiology
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• v.30 no.1
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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.

• The Korean Journal of Pharmacology
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• v.30 no.2
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• pp.145-152
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• 1994

As it has been reported that the depolarization induced acetylcholine(ACh) release is modulated by activation of presynaptic $A_1-adenosine$ heteroreceptor and various lines of evidence indicate the $A_2-receptor$ is present In hippocampus, this study was undertaken to delineate the role of adenosine receptors on hippocampal ACh release. Slices from the rat hippocampus were equilibrated with $[^3H]-choline$ and the release of the labelled product, $[^3H]-ACh$, which evoked by electrical stimulation(3 Hz, $5\;Vcm^{-1}$, 2 ms, rectangular pulses) was measured, and the influence of various agents on the evoked tritium outflow was Investigated. Adenosine$(0.3{\sim}100\;{\mu}M)$ and CPA$(0.1{\sim}30\;{\mu}M)$ decreased the $[^3H]-ACh$ release in a dose-dependent manner without changing the basal rate of release. DPCPX$(1{\sim}10\;{\mu}M)$, a selective $A_1-receptor$, antagonist, increased the $[^3H]-ACh$ release in a dose related fashion with slight increase of basal tritium release. And the effects of adenosine and CPA were significantly inhibited by $DPCPX(2\;{\mu}M)$ treatment. CPCA, a specific $A_2-agonist$, in concentration ranging from 0.3 to 30 ${\mu}M$, decreased the evoked tritium outflow, and these effects were also abolished by $DPCPX(2\;{\mu}M)$ treatment. But the CPCA effects were not affected by $DMPX(2\;{\mu}M)$, a specific Aa-antagonist, treatment. However, CGS 21680c, a recently introduced potent $A_2-agonist$, in concentration ranging from 0.1 to $10{\mu}M$, did not alter the evoked tritium outflow. These results indicate that the decrement of the evoked ACh release by adenosine is mediated by $A_1-heteroreceptor$, but $A_2-adenosine$ receptor is not involved in ACh release in the rat hippocampus.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.1
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• pp.13-17
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• 1997

Carbamazepine (CBZ), an anticonvulsant, has beeen reported to displace ligands at adenosine receptors. Several studies have demonstrated that as far as $A_2$adenosine receptors is concerned, CBZ acts as an antagonist. However, the situation with regard to Al receptors is less straightforward. In this study, we describe the effects of one-week CBZ treatment (25 mg/kg/day) on cerebrocortical $A_1$ adenosine receptors. $A_1$ adenosine receptor bindings as determined by using $[^3CH]DPCPX$ was not significantly altered in membranes prepared from CBZ-treated rats. However, there was a significant decrease in the $A_1$ adenosine receptor-mediated stimulation of $[^{35}S]GTP_{\gamma}S$ binding to cerebrocortical membranes prepared from CBZ-treated rats (20.0% decrease in basal activity; 17.8% decrease in maximal activity). The basal and $10^{-4}$ M forskolin-stimulated adenylyl cyclase activities were relatively unaffected by CBZ treatment, but 10 mM NaF-stimulated adenylyl cyclase activity was significantly reduced in CBZ-treated rats. It appears that one-week CBZ treatment caused an uncoupling of adenosine receptors from G proteins without alteration of $A_1$ adenosine receptor molecules, suggesting that CBZ acts as an agonist at $A_1$ adenosine receptors in rat brain.

• The Korean Journal of Physiology
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• v.30 no.1
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• pp.85-96
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• 1996

Adenosine and its analogues are known to possess analgesic effects and to be involved in the opiate-induced antinociception as well. This study was designed to investigate the effects of three adenosine agonists, 5'- (N-cyclopropyl) -carboxamidoadenosine(CPCA), 5'-N-ethylcarboxamidoadeno-sine (NECA) and $N^6-cyclohexyladenosine$ (CHA) on the signal transmission in the spinal cord and also to elucidate mechanisms of their actions in the anesthetized cat. All the tested adenosine agonists(i.v,) exerted inhibitory effects on the responsiveness of the wide dynamic range (WDR) cells, the inhibitory action of CHA, an adenosine $A_1$ receptor agonist, $(80{\mu}g/Kg)$ being most weak. The intravenous CPCA, an adenosine $A_2$ receptor agonist, $(20{\mu}g\;/Kg)$ and NECA, nonspecific adenosine receptor agonist, $(20{\mu}g\;/Kg)$ inhibited the responses of WDR cells to pinch and C fiber stimulation more strongly than those to brush and A fiber stimulation. CPCA (i.v.) also suppressed the responses of WDR cells to thermal stimulus. And all the CPCA-induced inhibitions were caffeine-reversible. When CPCA was directly applied onto the spinal cord or intravenously administered into the spinal cat, on average, about three quarters of the CPCA-induced inhibitory effect was abolished. On the other hand, in the animal with spinal lesions in the ipsilateral dorsolateral area, the CPCA-induced inhibition was comparable to that observed in the spinal cats. In conclusion, this study shows that adenosine agonists strongly suppress the responses of WDR cells to pinch, C fiber stimulation and thermal stimuli mainly through the supraspinal adenosine $A_2-receptors$.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.243-248
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• 2004

As diverse synthetic precursors of cyclic adenosine diphosphate ribose (cADPR), several adenosine derivatives in which azido or amino group is introduced at 2'- or 3'-position of the sugar moiety of adenosine were prepared from readily available adenosine via conventional protocols. These synthetic sequence employs very efficient reactions conditions that proceed at or below ambient temperature with actual yields of >80% for each individual step.

• Journal of Life Science
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• v.6 no.2
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• pp.120-128
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• 1996

In the screening of actinomycetes culture filtrate for inhibitor of adenosine deaminase, a novel inhibitor was found in a cultured broth of strain J-144K. The optimum conditions for the adenosine deaminase inhibitor production from the isolated strain J-144K were evaluated. This strain showed the maximum yield of adenosine deaminase inhibitor when grown at pH 7.0 and 30$\circ$C for 60 hours in the medium of 1.0% dextrose, 0.5% yeast extract, 0.5% peptone and 0.1% KH$_{2}$PO$_{4}$ under the aerobic condition. Through the activated charcoal extraction, methanol fractionation, Dowex 50 H$^{+}$ X-8 ion exchange column chromatography, Dowex CI$^{-}$ X-8 ion exchange column chromatography, and Sephadex G-15 gel filtration procedures, this inhibitor was purified with three materials.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1643-1648
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• 2010

Adenosine 5'-phosphonates have been reported as potential chain terminators against Hepatitis C virus (HCV); therefore, we developed convenient sequences for synthesis of modified adenosine 5'-phosphonates in which the hydroxyl group at 2' or 3'-position of the sugar moiety is substituted with the azido or amino group and the oxymethyl group at the 4'-position is modified by the ethylene or vinyl group. This synthetic sequence can provide six adenosine 5'-phosphonates via one protocol, and is considered to be very efficient and a convenient route of synthesis. An assay of adenosine 5'-phosphonate analogues (1, 2, 3, 4, 5, and 6) against HCV infection is now in progress.