• Title/Summary/Keyword: adrenergic activity

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Effects of ${\alpha}_1-Adrenergic$ Receptor Stimulation on Intracellular $Na^+$ Activity and Twitch Force in Guinea-Pig Ventricular Muscles

  • Chae, Soo-Wan;Gong, Q.Y.;Wang, D.Y.;Lee, Chin-O.
    • The Korean Journal of Physiology
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    • v.29 no.2
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    • pp.203-216
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    • 1995
  • The effects of ${\alpha}_1-adrenergic$ receptor stimulation on membrane potential, intracellular $Na^+$ activity, and twitch force were investigated in ventricular muscles from guinea-pig hearts. Action potentials, intracellular $Na^+$ activity, and twitch force of ventricular papillary muscles were measured simultaneously under various experimental conditions. Stimulation of the ${\alpha}_1-adrenergic$ receptor by phenylephrine produced variable changes in action potential duration, a slight hyperpolarization of the diastolic membrane potential, a decrease in intracellular $Na^+$ activity, and a biphasic inotropic response in which a transient negative inotropic response was followed by a sustained positive inotropic response. These changes were blocked by prazosin, an antagonist of the ${\alpha}_1-adrenergic$ receptor, but not by atenolol, an antagonist of the ${\beta}-adrenergic$ receptor. This indicates that the changes in membrane potential, intracellular $Na^+$ activity, and twitch force are mediated by stimulation of the ${\alpha}_1-adrenergic$ receptor, but not by stimulation of ${\beta}-adrenergic$ receptor. The decrease in intracellular $Na^+$ activity was not observed in quiescent muscles, depending on the rate of the action pontentials in beating muscles. The intracellular $Na^+$ activity decrease was substantially inhibited by tetrodotoxin. However, the decrease in intracellular $Na^+$ activity was not affected by an inhibition of the $Na^+-K^+$ pump. Therefore, the decrease in intracellular $Na^+$ activity mediated by the ${\alpha}_1-adrenergic$ receptor appears to be due to a reduction of $Na^+$ influx during the action potential, perhaps through tetrodotoxin sensitive $Na^+$ channels. Our study also revealed that the decrease in intracellular $Na^+$ activity might be related to the transient negative inotropic response. The intracellular $Na^+$ activity decrease could lower intracellular $Ca^{2+}$ through the $Na^+-Ca^{2+}$ exchanger and thereby produce a decline in twitch force.

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Practical and Effective Method for the Solubilization and Characterization of Mammalian ${\beta}$-adrenergic receptor

  • Shin, Chan-Young;Kim, Hee-Jin;Lee, Sang-Bong;Ko, Kwang-Ho
    • Biomolecules & Therapeutics
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    • v.1 no.2
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    • pp.188-195
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    • 1993
  • In order to understand the machanism of action and regulation of ${\beta}$-adrenergic receptor in terms of molecular level, the purification of receptor protein has a fundamental importance. Moreover, species differences among avian, amphibian and mammalian ${\beta}$-adrenergic receptors make it more important to purify mammalian ${\beta}$-adrenergic receptor. Because ${\beta}$-adrenergic receptor is an integral membrane protein, it must be solubilized from the membrane for the purification. The purpose of the present study was to solubilize and characterize the mammalian $\beta$-adrenergic receptor from guinea pig lung in quantities by more efficient and practical method eventually to purify receptor. Guinea pig lung membrane preparation was solubilized by sequential treatment of buffers containing low and high concentration of digitonin which are 0.2 and 1.2% respectively. About 50% of the total receptor pool was released by this double extraction procedure. The $\beta$-adrenoceptors in the digitonin extract were identified using the ${\beta}$-adrenergic antagonist, (-)-[$^3H$]-dihydroalprenolol ([$^3H$]DHA). The solubilized receptor retained all of the essential characteristics of membrane-bound receptor, namely saturability; stereoselectivity; high affinity to ${\beta}$-adrenergic drugs. For the measurement of soluble receptor activity, Sephadex G-50 chromatography method has been widely used. Inspite of its accuracy and wide acceptance, this technique employed troublesome column work which required long time to assay the activity of receptor. We employed another methods to measure receptor activity. When using 0.5% polyethylenimine pretreated GF/B glass fiber filter, filtration technique could be used to measure soluble receptor activity. This technique enabled us to reduce the total amount of time to assay by a factor of 4 as well as to detect soluble receptor. In the present study, we could establish more efficient and practical solubilization method of mammalian $\beta$-adrenergic receptor. The rapidity and high yield of this solubilization scheme, together with the favorable recovery of the receptor activity, are significant steps toward the ultimate purification of the mammalian $\beta$-adrenergic receptor. The result of this study together with more convenient purification method could provide large amount of purified receptor with ease for various research purposes.

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C-terminal Truncation Mutant of the Human ${\beta}_2$-adrenergic Receptor Expressed in E. coli as a Fusion Protein Retains Ligand Binding Affinity

  • Shin, Jin-Chul;Lee, Sang-Derk;Shin, Chan-Young;Lee, Sang-Bong;Ko, Kwang-Ho
    • Biomolecules & Therapeutics
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    • v.4 no.1
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    • pp.97-102
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    • 1996
  • To investigate whether human $\beta$$_2$-adrenergic receptor devoid of the C-terminal two transmembrane helices retain its ligand binding activity and specificity, 5'780-bp DNA fragment of the receptor gene which encodes amino acid 1-260 of human $\beta$$_2$-adrenergic receptor was subcloned into the bacterial fusion protein expression vector and expressed as a form of glutathione-S-transferase (GST) fusion protein in E. coli DH5$\alpha$. The receptor fusion protein was expressed as a membrane bound form which was verified by SDS-PAGE and Western blot. The fusion protein expressed in this study specifically bound $\beta$-adrenergic receptor ligand [$^3$H] Dihydroalprenolol. In saturation ligand binding assay, the $K_{d}$ value was 7.6 nM which was similar to that of intact $\beta$$_2$-adrenergic receptor in normal animal tissue ( $K_{d}$=1~2 nM) and the $B_{max}$ value was 266 fmol/mg membrane protein. In competition binding assay, the order of binding affinity of various adrenergic receptor agonists to the fusion protein was isoproterenol》epinephrine norepinephrine, which was similar to that of intact receptor in normal animal tissue. These results suggest that N-terminal five transmembrane helices of the $\beta$$_2$-adrenergic receptor be sufficient to determine the ligand binding activity and specificity, irrespective of the presence or absence of the C-terminal two transmembrane helices.s.s.s.

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Effects of ${\alpha}-,\;{\beta}-Adrenergic$, and Calcium Channel Blockers on Renin- Angiotensin System in Perfused Rat Heart

  • Park, Chang-Gyo
    • The Korean Journal of Physiology and Pharmacology
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    • v.2 no.1
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    • pp.55-62
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    • 1998
  • ${\alpha},\;{\beta}-Adrenergics$, and calcium channels were known to be related to inducing cardiac hypertrophy. Recently, it was reported that the cardiac renin-angiotensin system (RAS) was an important factor in ventricular hypertrophy. The present study was aimed to investigate the effects of ${\alpha},\;{\beta}-adrenergic$, and calcium channel blockers that might be involved in the regulation of cardiac RAS. The reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of renin gene in the perfused rat heart. Changes in angiotensin converting enzyme (ACE) activity and cyclic AMP (cAMP) content which were thought to play a role in inducing cardiac hypertrophy were measured in the perfused rat heart. The expression of renin gene was not only increased by isoproterenol with metoprolol-pretreatment but also increased by vasopressin treatment in the presence of calcium channel blocker, nifedipine or verapamil. Either prazosin alone or norepinephrine with prazosin-pretreatment significantly increased the ACE activity. However, isoproterenol with metoprolol-pretreatment significantly decreased the ACE activity. On the other hand, the ACE activity was not changed by vasopressin, nifedipine, or verapamil treatments. The content of cAMP was significantly increased by either isoproterenol or vasopressin treatment. According to these results, renin gene expression was associated with ${\beta}2$ - adrenoceptor and calcium channel. ACE activity was associated with ${\alpha}-\;and{\beta}2$ - adrenoceptor. In conclusion, ${\beta}2$ - adrenoceptor was important in cardiac renin gene expression and ACE activity and ${\alpha},\;{\beta}$ -adrenergic, and calcium channel blockers might be involved in the regulation of cardiac RAS in a complicated way.

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Xylazine-induced depression and its antagonism by α-adrenergic blocking agents (Xylazine의 진정효과와 α-adrenergic 수용체 봉쇄약물의 길항효과)

  • Kim, Chung-hui;Hah, Dae-sik;Kim, Yang-mi;Kim, Jong-shu
    • Korean Journal of Veterinary Research
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    • v.33 no.1
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    • pp.71-80
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    • 1993
  • The central nervous system depressant effect of xylazine and xylazine-ketamine was studied in chicken and mice. Intraperitoneal injection of xylazine(1~30 mg/kg) and xylazine(1~30 mg/kg)-ketamine(100 mg/kg) induced a loss of the righting reflex in chicken and mice, respectively. These effects of xylazine were dose-dependent. The results obtained were as follows; 1. The effect of xylazine-induced depression was antagonized by adrenergic antagonists having ${\alpha}_2$-blocking activity(yohimbine, tolazoline, piperoxan and phentolamine). 2. Yohimbine was most effective in the reduction of the CNS depression by xylazine. 3. Phenoxybenzamine and prazosin did not reduced CNS depression by xylazine in both species. 4. Labetalol (${\alpha}_1$, ${\beta}_1$-adrenergic antagonist) and propranolol(${\beta}$-adrenergic blocking agent) were not effective in reducing xylazine induced depression. 5. Cholinergic blocking agents (atropine and mecamylamine), a dopaminergic antagonist (Haloperidol), a histamine $H_1$-antagonist(chlorpheniramine), a histamine $H_2$-antagonist(cimetidine), a serotonergic-histamine $H_1$ antagonist(cyproheptadine) were not effective in reducing xylazine-induced depression. 6. Xylazine-induced depression is mediated by ${\alpha}_2$-adrenergic receptors and appears not to be involved in cholinergic, dopaminergic, serotonergic or histaminergic pathways.

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Localization of adrenergic receptors in bovine esophageal groove (소(牛) 식도구 평활근의 Adrenergic receptor 존재부위에 관한 연구)

  • Kang, Tong-mook;Cho, Je-yoel;Park, Jun-hong;Yang, Il-suk
    • Korean Journal of Veterinary Research
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    • v.33 no.4
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    • pp.617-622
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    • 1993
  • The preliminary studies on the localization of adrenoceptors were performed on smooth muscle strips of bovine esophageal groove. The mechanical activity of the muscle strip was recorded isometrically in vitro.w In the bottom circular muscle strips. the excitatory ${\alpha}-adrenergic$ responses were not blocked by tetrodotoxin$(2.1{\times}10^{-6}M)$ and denervation which was carried by cold storage of strips for 48 hrs in Tyrode's solution at $5-6{^{\circ}C}$ without oxygen supply. These excitatory ${\alpha}-adrenergic$ responses were partially blocked by atropine. In the lip longitudinal muscle strips, the inhibitory${\beta}-adrenergic$ responses were not blocked by pretreatment of tetrodotoxin and atropine. The results suggest that ${\beta}-adrenergic$ receptors mediating relaxations are located on the postsynaptic smooth muscle cells, whereas ${\beta}-adrenergic$ receptors mediating contractions are located both in the smooth muscle cells and in the cholinergic neurones.

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The Analgesic Effect and the Mechanism of Electroacupuncture on Thermal Hyperalgesia in the Rat Model of Collagenase-induced Arthritis: Mediation by Adrenergic Receptors (Collagenase-induced Arthritis Rat Model에서 Thermal Hyperalgesia에 대한 전침(電鍼)의 진통효과(鎭痛效果) 및 기전연구: Adrenergic Mechanism에 대(對)한 연구(硏究))

  • Seo, Byung-Kwan;Park, Dong-Suk;Baek, Yong-Hyeon
    • Journal of Acupuncture Research
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    • v.28 no.2
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    • pp.57-67
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    • 2011
  • 목적 : Collagenase-induced osteoarthritis(OA) 동물 모델에서 전침의 adrenergic mechanism을 연구하고자 한다. 방법 : Collagenase-induced arthritis(CIA)를 유발하기 위하여 5주령의 male Sprague-Dawley rat의 뒷다리 좌측 무릎 관절에 0.05ml의 4mg/ml collagenase solution을 intra-articular 주입하고, 다시 4일 후에 같은 부위에 같은 농도의 collagenase solution을 intra-articular boosting injection 시행한 뒤, gross, histopathological features 및 biomarker activity 변화를 관찰하였다. 예비실험을 통하여 CIA rat model에서 진통효과를 발휘하는 것으로 확인한, 족삼리(足三里) ($ST_{36}$)에 대한 저빈도 train pulse EA stimulation (2Hz, 0.07 mA, 0.3ms)을 침치료 방법으로 적용하였다. 전침의 진통기전을 확인하기 위하여, ${\alpha}1$-adrenergic antagonist (prazosin, 1 mg/kg, i.p.), ${\alpha}2$-adrenergic receptor antagonist (yohimbine, 2mg/kg, i.p.), ${\alpha}1$-adrenergic receptor agonist(phenylephrine, 2mg/kg, i.p.), ${\alpha}2$-adrenergic receptor agonist(clonidine, $40{\mu}g$/kg, i.p.)을 전침시행 20분 전에 복강 내로 전처치하였다. Tail flick unit(Ugo Basile Model 7360)을 이용하여 열자극에 대한 통증역치를 측정하였다. 결과 : 퇴행성관절염 징후(gross, histopathological features)와 통증역치의 변화가 최대값을 나타내는 CIA 유발 4주차에 저빈도 전침자극(train pulse, 2Hz, 0.07mA, 0.3ms)을 족삼리($ST_{36}$)에 적용하였으며, 족삼리 전침의 진통효과는 ${\alpha}2$-adrenergic receptor antagonist(yohimbine, 2mg/kg, i.p.)전처치에 의해 억제되었으나, ${\alpha}1$-adrenergic antagonist(prazosin, 1 mg/kg, i.p.)전처치에는 억제되지 않았다. 또 ${\alpha}2$-adrenergic receptor agonist(clonidine, $40{\mu}g$/kg, i.p.)의 전처치를 통하여 유의한 synergistic analgesic effect가 관찰되었으나, ${\alpha}1$-adrenergic receptor agonist(phenylephrine, 2mg/kg, i.p.)의 전처치는 전침의 진통효과에 synergistic effect를 미치지 않는 것으로 나타났다. 결론 : 저빈도 족삼리 전침은 CIA로 유발된 염증성 통증에 대하여 진통효과를 발휘하며, 이는 ${\alpha}2$-adrenergic receptor에 의하여 매개되는 것으로 보이며 ${\alpha}1$-adrenergic receptor는 영향을 미치지 않는 것으로 사료된다.

Body-fat Suppressive Effects of Capsaicin through $\beta$-adrenergic Stimulation in Rats Fed a High-fat Diet (고지방식이를 섭취시킨 흰쥐에서 $\beta$-adrenergic 활성의 증가에 의한 Capsaicin의 체지방 감소효과)

  • 주종재
    • Journal of Nutrition and Health
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    • v.32 no.5
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    • pp.533-539
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    • 1999
  • The effects of capsaicin, a pungent principle of hot red pepper, on body fat gain, balance serum lipid values were investigated in rats fed a high-fat(30%) diet. Administration of capsaicin by dietary administration caused a complete cessation of increased in body weight and fat gain induced by the high-fat diet. However, energy intake and body protein gain were not affected by capsaicin. Therefore, the suppression of body fat gain by capsaicn was believed due to an increased in energy expenditure. Simultaneous administration of capsaicin and a $\beta$-adrenergic blocker, propranolo, resulted in the inhibition of changes in body fat gain by capsaicin without remained unchanged, indicating an increase in the number of mitochondria in brown adipose tissue. Therefore, it appears that capsaicin possesses potent body fat suppressive effects mediated by $\beta$-adrenergic stimulation in which brown adipose tissue may be involved. On the other hand, capsaicin had no effects on serum triglyceride, total cholesterol or HDL-cholesterol levels. These results are in contrast to those reported by other investigators. Perhaps expression of the effects of capsaicin on plasma lipids is a rather complicated process, dependent on the type of diet administered, fat content of the diet, period and route of capsaicin administration, and species and strain of animals used.

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Mechanism of Increased Adrenergic Activities in Hypertension Induced by Chronic Inhibition of NOS (NOS만성억제로 인한 고혈압에서 아드레날린성 활성증가기전)

  • 정국현;이석용
    • YAKHAK HOEJI
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    • v.45 no.1
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    • pp.85-92
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    • 2001
  • Nitric oxide is a tonically produced vasodilator that maintains blood pressure in the normal animal. The chronic inhibition of nitric oxide synthase (NOS) elicits the hypertension in rats. However, the mechanism of hypertension induced by chronic inhibition of NOS is not clear. Thus, to clarify the mechanism of the occurance of hypertension, the changes in $\alpha$-adrenergic systems in rats treated with NOS inhibitors for 21 days were examined. Chronic administration of L-NAME significantly increased in the basal blood pressure, but chronic administration of 7-nitroindazole did not. Phenylephrine and G-protein stimulator elicited the more potent contraction in the aorta of the L-NAME-induced hypertensive rats. However when the contractile responses by phenylephrine and G-protein stimulator were calculated the proportion to the contraction by 25 mM KCL, there was no difference between the vehicle-treated rats and the L-NAME-treated rats. The density of $\alpha$-adrenergic receptors in aortic tissue was not changed by the chronic inhibition of NOS. These results suggest that hypertension induced by chronic inhibition of NOS is due to the inhibition of eNOS and the increased responses to the adrenergic drugs are due to the changes of the intracellular contactile mechanism of aortic tissue rather than the changes of receptor density.

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A network pharmacology approach to explore the potential role of Panax ginseng on exercise performance

  • Kim, Jisu;Lee, Kang Pa;Kim, Myoung-Ryu;Kim, Bom Sahn;Moon, Byung Seok;Shin, Chul Ho;Baek, Suji;Hong, Bok Sil
    • Korean Journal of Exercise Nutrition
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    • v.25 no.3
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    • pp.28-35
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    • 2021
  • [Purpose] As Panax ginseng C. A. Meyer (ginseng) exhibits various physiological activities and is associated with exercise, we investigated the potential active components of ginseng and related target genes through network pharmacological analysis. Additionally, we analyzed the association between ginseng-related genes, such as the G-protein-coupled receptors (GPCRs), and improved exercise capacity. [Methods] Active compounds in ginseng and the related target genes were searched in the Traditional Chinese Medicine Database and Analysis Platform (TCMSP). Gene ontology functional analysis was performed to identify biological processes related to the collected genes, and a compound-target network was visualized using Cytoscape 3.7.2. [Results] A total of 21 ginseng active compounds were detected, and 110 targets regulated by 17 active substances were identified. We found that the active compound protein was involved in the biological process of adrenergic receptor activity in 80%, G-protein-coupled neurotransmitter in 10%, and leucocyte adhesion to arteries in 10%. Additionally, the biological response centered on adrenergic receptor activity showed a close relationship with G protein through the beta-1 adrenergic receptor gene reactivity. [Conclusion] According to bioavailability analysis, ginseng comprises 21 active compounds. Furthermore, we investigated the ginseng-stimulated gene activation using ontology analysis. GPCR, a gene upregulated by ginseng, is positively correlated to exercise. Therefore, if a study on this factor is conducted, it will provide useful basic data for improving exercise performance and health.