• Title/Summary/Keyword: Selective inhibitor

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Expression of Serotonin(5-HT) Receptor Isotypes in Reproductive Organs of Male Rat (수컷 흰쥐 생식기관에서의 세로토닌 수용체 아형 유전자 발현)

  • 이성호
    • Development and Reproduction
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    • v.6 no.2
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    • pp.111-115
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    • 2002
  • 5-Hydroxytryptamine(5-HT; serotonin) system has been implicated in the modulation of male sexual behaviors and the secretion of reproductive hormones. In human males, selective serotonin re-uptake inhibitors(SSRIs) are known to improve the major male sexual dysfunction, premature ejaculation, through the central nervous system-mediated pathways. As numerous hormone and local factors, 5-HT may have peripheral role in the regulation of male sexual function. The expression of 5-HT receptor subtypes in the target tissue, however, has not been explored yet. The present study was undertaken to test whether the 5-HT receptor subtypes are expressed in the reproductive tissues of male rat, especially in ejaculatory machinery such as seminal vesicle and vas deferens. To do this, reverse transcription-polymerase chain reaction(RT-PCR) and Southern blot analysis were employed. The transcripts for the 1A, 1B and 2C subtypes of 5-HT receptor were amplified in all the tested tissues. The present study demonstrated the expression of 5-HT receptor in the rat ejaculatory machinery, suggesting that 5-HT may play a pivotal role in the male sexual function via not only central pathway but also peripheral route. Further study on the receptor subtype-specific effect and their harmonized mode of action will be needed to establish the understanding of ejaculation mechanism and drug design.

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A DOUBLE BLIND CROSS-OVER COMPARISON OF ANTIDEPRESSANT AND ANTIANXIETY EFFECTS OF PAROXETINE AND PLACEBO IN CHILD-ADOLESCENT AND ADULT DEPRESSIVE NEUROSIS (소아 ${\cdot}$ 청소년 및 성인 우울신경증 환자에 대한 Paroxetine의 항우울 및 항불안 효과 검증 : 위약과의 이중맹 교차 비교실험)

  • Kim, S. Peter;Hong, Kyung-Sue
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.5 no.1
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    • pp.83-92
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    • 1994
  • Paroxetine is a potent and selective serotoin re-uptake inhibitor. It is well known as an effective and safe antidepressant and increasingly used for neurotic or non-psychotic depression with anxiety symptoms. The present study assessed antidepressant and antianxiety efficacy and tolerability of paroxetine against placebo in child-adolescent and adult depressive neurosis patients. 232 subjects aged 8-55 years and meeting DSM-III-R criteria for depressive neurosis or dysthymia were divided into 8 subgroups according to their sex and age(8-11 yeard old, 12-17 years old, 18-35 years old and 36-55 years old subgroup in each male and female group). In each subgroup, the randomly assigned half of the patients were treated with paroxetine(10-30mg/day) and the others with placebo for the first 2 weeks in double blind fashion. After 1 week of drug-washout period, paroxetine and placebo groups were crossed over. The depression and anxiety symptoms were assessed with Hamilton Depression Scale(HDS) and Hamilton Anxiety Scale(HAS) at baseline and every 1 week during the trial periods. The levels of reduction in HDS and HAS scores from baseline after 2-week trial were compared between paroxetine- and placebo- treated periods by paired t-test. In all the 8 subgroups, statistically significant differences between paroxetine and placebo were found on the antidepressant efficacy after 2-week treatment. The antidepressant efficacy of paroxetine compared to placebo was most prominent in child and adolescent female groups. On anxiety symptoms, paroxetine was also significantly more effective than placebo. The antianxiety efficacy of paroxetine compared to placebo was most prominent in male and female child groups and young adult female group aged 18-35 years. As for the adverse effects of paroxetine, 3 out of 232 subjects reported mild indigestion and abdominal pain. however, in all the 3 cases, the symptoms improved without reduction of dosage or discontinuation of the drug. In conclusion, paroxetine showed significantly higher antidepressant and antianxiety efficacy compared to placebo in child-adolescent and adult depressive neurosis patients after 2-week treatment. Further trials of paroxetine in depressive neurosis are warranted to elucidate the long-term antidepressant and antianxiety efficacy of paroxetine.

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Signal Transduction Factors on the Modulation of Radiosusceptibility in K562 Cells (K562 세포의 방사선 감수성 변화에 영향을 미치는 신호전달인자)

  • Yang Kwang Mo;Youn Seon-Min;Jeong Soo-Jin;Jang Ji-Yeon;Jo Wol-Soom;Do Chang-Ho;Yoo Y대-Jin;Shin Young-Cheol;Lee Hyung Sik;Hur Won Joo;Lim Young-Jin;Jeong Min-Ho
    • Radiation Oncology Journal
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    • v.21 no.3
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    • pp.227-237
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    • 2003
  • Purpose: The human chronic myelogenous leukemia cell line, K562, expresses the chimeric bcr-abl oncoprotein, whose deregulated protein tyrosine kinase activity antagonizes via DNA damaging agents. Previous experiments have shown that nanomolar concentrations of herbimycin A (HWA) coupled with X-irradiation have a synergistic effect in inducing apoptosis in the Ph-positive K562 leukemia cell line, but genistein, a PTK inhibitor, is non selective for the radiation-induced apoptosils on $p210^{bcr/abl}$ protected K562 cells. In these experiments, the cytoplasmic signal transduction pathways, the Induction on a number of transcription factors and the differential gene expression in this model were investigated. Materials and Methids: K562 cells in the exponential growth phase were used in this study. The cells were irradiated with 0.5-12 Gy, using a 6 Mev Linac (Clinac 1800, Varian, USA). Immediately after irradiation, the cells were treated with $0.25/muM$ of HMA and $25/muM$ of genistein, and the expressions and the activities of abl kinase, MAPK family, NF- kB, c-fos, c-myc, and thymidine kinase1 (TK1) were examined. The differential gene expressions induced by PTK inhibitors were also investigated. Results: The modulating effects of herbimycin A and genistein on the radiosensitivity of K562 cells were not related to the bcr-abl kinase activity. The signaling responses through the MAPK family of proteins, were not involved either in association with the radiation-induced apoptosis, which is accelerated by HMA, the expression of c-myc was increased. The combined treatment of genistein, with irradiation, enhanced NF- kB activity and the TK1 expression and activity. Conclusion: The effects of HMA and genistein on the radiosensitivity on the K562 cells were not related to the bcr-abl kinase activity in this study, another signaling pathway, besides the WAPK family responses to radiation to K562 cells, was found. Further evaluation using this model will provide valuable information for the optional radiosensitization or radioprotection.

Effect of TNF-$\alpha$ Gene Transfer to Respiratory Cancer Cell Lines on Sensitivity to Anticancer drugs (호흡기계암세포주에서 TNF-$\alpha$ 유전자의 이입이 항암제 감수성에 미치는 효과)

  • Mo, Eun-Kyung;Lee, Jae-Ho;Lee, Kye-Young;Yoo, Chul-Gyu;Kim, Young-Whan;Han, Sung-Koo;Shim, Young-Soo;Choi, Hyung-Seok
    • Tuberculosis and Respiratory Diseases
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    • v.42 no.3
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    • pp.302-313
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    • 1995
  • Background: Tumor necrosis factor(TNF) showed antitumor cytolytic effects on sensitive tumor cells in numerous in vivo and in vitro studies. But it could not be administered systemically to human because of severe systemic adverse effects at effective concentrations against tumor cells. Many studies showed that a high concentrations of TNF in the local milieu may evoke in vivo TNF-responsive mechanisms sufficient to suppress tumor growth. Recently developed technique of TNF gene transfer to tumor cells using retrovirus vector could be a good candidate for local TNF administration. TNF is also known to synergistically enhance in vitro cytotoxicity of chemotherapeutic drugs targeted to DNA topoisomerase II against TNF-sensitive tumor cell lines. In this study the in vitro chemosensitivity against DNA topoisomerase II targeted chemotherapeutic drugs was evaluated using some respiratory cancer cell lines to which TNF gene had been transferred. Method: NCI-H2058, a human mesothelioma cell line, A549, a human lung adenocarcinoma cell line and WEHI 164 cell line, a murine fibrosarcoma cell line were treated with etoposide and doxorubicin, which are typical topoisomerase II - targeted chemotherapeutic agents, at different concentration. The resultant cytotoxicity was measured by MIT assay. Then the cytotoxicity of the same chemotherapeutic agents was measured after TNF-$\alpha$ gene-transfer and the two results were compared. Results: The cytotoxicity was not increased significantly in WEHI164 cell line and A549 cell line but statistically significant increase was observed in H2058 cell line when TNF-$\alpha$ gene was transferred(p<0.05). Conclusion: These findings show that TNF-$\alpha$ gene transfer to respiratory cancer cell lines results in variable effects on chemosensitivity against topoisomerase II inhibitor among different cell lines in vitro and can be additively cytotoxic in certain selective tumor cell lines.

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Effects of Olanzapine on the Schedule-Induced Polydipsic Rats (Olanzapine이 백서의 Schedule-Induced Polydipsia에 미치는 영향)

  • Lee, Gi-Chul;Lee, Kyung-Kyu;Chang, Hwan-Il;Lee, Jung-Ho;Kim, Hyun-Woo;Ha, Jun-Myung;Jeong, Jae-Hyun;Jeong, Hong-Kyung
    • Korean Journal of Biological Psychiatry
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    • v.6 no.2
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    • pp.240-245
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    • 1999
  • Object : This study was designed to evaluate the effects of olanzapine on the schedule-induced polydipsia(SIP) which is one of animal model of obsessive-compulsive disorder in rats. We administered olanzapine as a serotonin and dopamine blocking agent, fluoxetine as a selective serotonin reuptake inhibitor, and haloperidol for the dopamine antagonist to rats which showed schedule-induced polydipsic behavior. Methods : Spraque-Dawley rats weighing 200-250gm were individually housed and maintained and allowed free access to water. The rats were placed on a restricted diet. To induce polydipsia, rats were placed in the cage where a pellet dispenser automatically dispensed 90mg pellets on a fixed-time 60 seconds(FT-60s) feeding schedule over 150 minute test session per day. Water was available at all times in the cage. After 4 weeks of daily exposure to the FT 60s feeding schedule, experimental rats met a predetermined criterion for polydipsic behavior(greater than 3 times of water per session on average). 5 groups of rats were administered olanzapine(3mg/kg, i.p), olanzapine(10mg/kg, i.p), fluoxetine(5mg/kg, i.p.), haloperidol(0.1mg/kg, i.p.), and vehicle(1cc/kg, i.p.) for 3 weeks. The rats were tested once a week to access schedule induced polydipsic behavior. Water bottles were weighed before and after the 150-minute test session. The chronic effects of administration of experimental drugs on schedule induced polydipsic behavior were analyzed with ANOVA and Scheffe test as a posthoc comparison. In order to measure water consumption in non-polydipsic food-deprived rats, a separate group of rats(N=8) were individually housed and given a single bolus(14.5gm) of food per day which maintained them at their average body weight. Results and Conclusion : The results were as follows ; 1) After 4 weeks of scheduled feeding procedure, the experimental group showed significant differences than the bolus control in the amount of water consumption as compared with their average water intakes for 4 weeks. At the same periods, there were no differences between the experimental group and the bolus control in the body weight. 2) The fluoxetine group showed significant decrease in the amount of water intake over the 3 weeks of drug treatment as compared with their average amount of polydipsic water intakes. The olanzapine 3mg group showed significant decrease in the amount of water intake at 3rd weeks of drug treatment as compared with their average amount of polydipsic water intakes. The olanzapine 10mg group showed significant decrease in the amount of water intake at 2nd and 3rd weeks of drug treatment as compared with their average amount of polydipsic water intakes. However, the haloperidol group and the vehicle control group showed no changes of amounts of water intake for 3 weeks of treatment as compared with their average amount of polydipsic water intakes. 3) The fluoxetine group showed significantly lower amounts of water intake than the haloperidol group at 2nd weeks of drug treatment. And also the fluoxetine group showed significantly lower amounts of water intake than the haloperidol group and the vehicle control at 3rd weeks of drug treatment. The olanzapine 3mg group and the olanzapine 10mg group showed significantly lower amounts of water intake than the haloperidol group and the vehicle control at 3rd weeks of drug treatment. Above findings suggest that the fixed time feeding procedure for schedule-induced polydipsia as an animal model of obsessive compulsive disorder was effective to the evaluation of pharmacological challenge study. The authors assume that the serotonin hypothesis and the serotonin-dopamine interaction hypothesis are preferred to the dopamine hypothesis in the biological etiology of obsessive-compulsive disorder.

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Hypoxia-dependent mitochondrial fission regulates endothelial progenitor cell migration, invasion, and tube formation

  • Kim, Da Yeon;Jung, Seok Yun;Kim, Yeon Ju;Kang, Songhwa;Park, Ji Hye;Ji, Seung Taek;Jang, Woong Bi;Lamichane, Shreekrishna;Lamichane, Babita Dahal;Chae, Young Chan;Lee, Dongjun;Chung, Joo Seop;Kwon, Sang-Mo
    • The Korean Journal of Physiology and Pharmacology
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    • v.22 no.2
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    • pp.203-213
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    • 2018
  • Tumor undergo uncontrolled, excessive proliferation leads to hypoxic microenvironment. To fulfill their demand for nutrient, and oxygen, tumor angiogenesis is required. Endothelial progenitor cells (EPCs) have been known to the main source of angiogenesis because of their potential to differentiation into endothelial cells. Therefore, understanding the mechanism of EPC-mediated angiogenesis in hypoxia is critical for development of cancer therapy. Recently, mitochondrial dynamics has emerged as a critical mechanism for cellular function and differentiation under hypoxic conditions. However, the role of mitochondrial dynamics in hypoxia-induced angiogenesis remains to be elucidated. In this study, we demonstrated that hypoxia-induced mitochondrial fission accelerates EPCs bioactivities. We first investigated the effect of hypoxia on EPC-mediated angiogenesis. Cell migration, invasion, and tube formation was significantly increased under hypoxic conditions; expression of EPC surface markers was unchanged. And mitochondrial fission was induced by hypoxia time-dependent manner. We found that hypoxia-induced mitochondrial fission was triggered by dynamin-related protein Drp1, specifically, phosphorylated DRP1 at Ser637, a suppression marker for mitochondrial fission, was impaired in hypoxia time-dependent manner. To confirm the role of DRP1 in EPC-mediated angiogenesis, we analyzed cell bioactivities using Mdivi-1, a selective DRP1 inhibitor, and DRP1 siRNA. DRP1 silencing or Mdivi-1 treatment dramatically reduced cell migration, invasion, and tube formation in EPCs, but the expression of EPC surface markers was unchanged. In conclusion, we uncovered a novel role of mitochondrial fission in hypoxia-induced angiogenesis. Therefore, we suggest that specific modulation of DRP1-mediated mitochondrial dynamics may be a potential therapeutic strategy in EPC-mediated tumor angiogenesis.

A Study on the Post-Receptor Mechanism of Adenosine Receptor on Acetylcholine Release in the Rat Hippocampus (흰쥐 해마에서 Acetylcholine 유리에 관여하는 Adenosine Receptor의 Post-Receptor 기전에 관한 연구)

  • Choi, Bong-Kyu;Oh, Jae-Hee
    • The Korean Journal of Pharmacology
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    • v.30 no.3
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    • pp.263-272
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    • 1994
  • Since it was been reported that the depolarization-induced ACh release is inhibited by activation of presynaptic $A_1-adenosine$ heteroreceptor in hippocampus, a large body of experimental data on the post-receptor mechanism of this process has been accumulated. But, the post-receptor mechanism of presynaptic $A_1-adenosine$ receptor on the ACh release has not been clearly elucidated yet. Therefore, it was attempted to clarify the post-receptor mechanisms of the $A_1-adenosine$ receptor-mediated control of ACh release in this study. Slices from rat hippocampus were equilibrated with $^3H-choline$ and the release of the labelled products was evoked by electrical stimulation (3 Hz, 5 $VCm^{-1}$, 2ms, rectangular pulses), and the influence of various agents on the evoked tritium-outflow was investigated. Adenosine, in concentrations ranging from $0.3{\sim}300\;{\mu}M$, decreased the ACh release in a dose-dependent manner, without affecting the basal rate of release. The adenosine effects were significantly inhibited by $DPCPX\;(2\;{\mu}M)$, a selective $A_1-receptor$ antagonist. The responses to N-ethylmaleimide $(10&30{\mu}M)$, a SH-alkylating agent of G-protein, were characterized by increments of the evoked ACh-release and the basal release, and the adenosine effects were completely abolished by NEM pretreatment. PDB $(1{\sim}10\;{\mu}M)$, a specific protein kinase C (PKC) activator, increased, whereas PMB $(0.03{\sim}1\;mg)$, a PKC inhibitor, decreased the evoked ACh-release, and the adenosine effects were not affected by these agents. Nifedipine $(1\;{\mu}M)$, a $Ca^{2+}\;-channel$ blocker of dihydropyridine analogue, significantly inhibited the adenosine effect, but glibenclamide, a $K^+-channel$ blocker, did not. Finally, 8-bromo cyclic AMP $(100\;&\;300{\mu}M)$, a membrane-permeable analogue of cAMP, did not alter the ACh release, but adenosine effects were inhibited by pretreatment with large dose of 8-br-cAMP $(300\;{\mu}M)$. These results indicate that the decrement of the evoked ACh-release by $A_1-adenosine$ receptor is mediated by the G-protein, and nifedipine-sensitive $Ca^{2+}-channel$ and adenylate cyclase system are coupled partly to this effect, and that protein kinase C and glibenclamide-sensitive $K{^+}-channel$ are not involved in this process.

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H. pylori Infection and Gastric Carcinogenesis (H. pylori Infection 감염과 위암 발생)

  • Han Sang-Uk;Cho Yong-Kwan;Chung Jae-Yun;Park Hyun-Jin;Kim Young-Bae;Nam Ki-Taek;Kim Dae-Yong;Joo Hee-Jae;Choi Jun-Hyuk;Kim Jin-Hong;Lee Ki-Myung;Kim Myung-Wook;Hahm Ki-Baik
    • Journal of Gastric Cancer
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    • v.2 no.2
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    • pp.73-80
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    • 2002
  • In spite the fact that H. pylori infection might be the causative organisms of acute and chronic gastritis, peptic ulcer diseases and the definition as the class I carcinogen by WHO IARC, still debates exist about the relationship between H. pylori and gastric carcinogenesis. Epidemiological and animal studies demonstrated a link between gastric cancer and chronic infection with H, pylori, but the exact mechanism responsible for the development of gastric cancer in H. pylori-infected patients still remain obscure. In order to declare the clear association, definate evidences like that decrement in the incidence of gastric cancer after the eradication of H. pylori in designated area compared to noneradicated region or the blockade of specific mechanism acting on the carcinogenesis by H. pylori infection. The other way is to identify the upregulating oncogenes or downregulating tumor suppressor genes specifically invovled in H. pylori-associated carcinogenesis. For that, we established the animal models using C57BL/6 mice strain. Already gastric carcinogenesis was developed in Mongolian gerbils infected with H. pylori, but there has been no development of gastric cancer in mice model infected with H. pylori after long-term evaluation. Significant changes such as atrophic gastritis were observed in mice model. However, we could observe the development of mucosal carcinoma in the stomach of transgenic mice featuring the loss of TGF-beta sig naling by the expressions of dominant negative forms of type II receptor specifically in the stomach. Moreover, the incidence of gastric adenocarcinoma was significantly increased in group administered with both MNU and H. pylori infection than MNU alone, signifying that H. pylori promoted the gastric carcinogenesis and there might be host susceptibility genes in H. pylori-associated gastric carcinogenesis. Based on the assumption that chronic, uncontrolled inflammation might predispose to carcinogenesis, there have been several evidences showing chronic atrophic gastritis predisposed to gastric carcinogenesis in H. pylori infection. Although definite outcome of chemoprevention was not drawn after the longterm administration of anti-inflammatory drug in H. pylori infection, the actual incidence of atrophic gastritis and molecular evidence of chemoprevention could be obtained. Selective COX-2 inhibitor was effective in decreasing the development of gastric carcinogenesis provoked by H. pylori infection and carcinogen like in chemoprevention of colon carcinogenesis.

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Effectiveness of Multimodal Pain Control in Early Phase After Arthroscopic Rotator Cuff Repair (관절경하 회전근 개 봉합술 후 다중 통증 조절법을 이용한 초기 통증 조절의 유용성)

  • Park, Chang-Min;Kim, Jong-Hae;Kim, Suk-Jun;Choi, Chang-Hyuk
    • Clinics in Shoulder and Elbow
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    • v.15 no.1
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    • pp.1-7
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    • 2012
  • Purpose: The purpose of this study was to identify the effectiveness of multimodal pain control method in an early phase after arthroscopic rotator cuff repair, under interscalene brachial plexus block, this study was performed. Materials and Methods: The study was progressed with the 80 cases of arthroscopic rotator cuff repair. Interscalene brachial plexus block was used to all of the 80 cases and patients were divided into 2 groups. Group A consisted of patients injected with bupivacaine, through subacromial space catheter after surgery, and group B consisted of patients with additional method of multimodal pain control using oral opioids, acetaminophen-tramadol complex and selective COX2 inhibitor. Subacromial cathter was removed after injection in both groups. The pain during the day time and night time was compared on the operation day, postoperative 1st, 2nd, 3rd day and 2nd weeks, and it was measured with VAS (visual analogue scale) score. Additionally, the number of ketolorac injection and side-effect related to analgesics was compared between the 2 groups. Results : The mean VAS score of night time on the operation day and day/night time pain of the 1st, 2nd, 3rd day and 2nd weeks was 7.4, 7.0/6.8, 4.5/5.2, 4.8/5.0, 2.2/2.7 on group A and 6.5, 4.3/5.4, 3.2/4.3, 3.0/4.1, 2.4/2.5 on group B, respectively. Significant difference was observed in the night pain on the operation day, 1st, 2nd, 3rd day time and 1st night time pain (p<.05). The average number of ketololac injection was 1.1 and 0.5 in each group, and there was no difference in the frequency of side effects. Conclusion: Multimodal pain control method, after arthroscopic rotator cuff repair, showed an effective early pain control and improved patients' satisfaction.

A Study on the Post-Receptor Mechanism of Adenosine Receptor on Norepinephrine Release in the Rat Hippocampus (흰쥐 해마에서 Norepinephrine 유리에 미치는 Adenosine Receptor의 Post-Receptor 기전에 관한 연구)

  • Choi, Bong-Kyu;Kim, Do-Kyung;Yang, Kyung-Moo
    • The Korean Journal of Pharmacology
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    • v.32 no.1
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    • pp.1-11
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    • 1996
  • Since it has been reported that the depolarization-induced norepinephrine (NE) release is inhibited by activation of presynaptic $A_1-adenosine$ heteroreceptor in hippocampus, a large body of experimental data on the post-receptor mechanism of this process has been accumulated. But, the post-receptor mechanism of presynaptic $A_1-adenosine$ receptor on the NE release has not been clearly elucidated yet. Therefore, it was attempted to clarify the post-receptor mechanisms of the $A_1-adenosine$ receptor-mediated control of NE release in this study. Slices from rat hippocampus were equilibrated with $^3H-norepinephrine$ and the release of the labelled products was evoked by electrical stimulation (3 Hz, 5 $Vcm^{-1}$, 2 ms, rectangular pulses), and the influence of various agents on the evoked tritium-outflow was investigated. Adenosine, in concentrations ranging from $1{\sim}30{\mu}M$, decreased the NE release in a dose-dependent manner, without affecting the basal rate of release. The adenosine effects were significantly inhibited by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, $2{\mu}M$), a selective $A_1-receptor$ antagonist. The responses to N-ethylmaleimide (NEM, 10 & $30{\mu}M$), a SH-alkylating agent of G-protein, were characterized by increments of the evoked NE-release and the basal release, and the adenosine effects were completely abolished by NEM pretreatment. $4{\beta}-Phorbol$ 12,13-dibutyrate (PDB, $1{\mu}M$), a specific protein kinase C (PKC) activator, increased the evoked NE release, whereas polymyxin B sulfate (PMB,0.1 mg), a PKC inhibitor, decreased the release, and the adenosine effects were inhibited by these agents. Nifedipine $(1{\mu}M)$, a $Ca^{2+}-channel$ blocker of dihydropyridine analogue, did not affect the adenosine effect. Tetraethylammonium (TEA, 3 mM) increased the evoked NE release, and inhibited the adenosine effects, but glibenclamide, a ATP dependent $K^+-channel$ blocker, did not. Finally, 8-bromo cyclic AMP (100 & $300{\mu}M$), a membrane-permeable analogue of cAMP, did not alter the NE release, but adenosine effects were inhibited by pretreatment with 8br-cAMP. These results suggest that the decrement of the evoked NE-release by $A_1-adenosine$ receptor is mediated by the C-protein, which is coupled to protein kinase C, adenylate cyclase system and TEA sensitive $K^+-channel$, and that nifedipine-sensitive $Ca^{2+}-channel$ and glibenclamide-sensitive $K^+-channel$ are not involved in this process.

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