• 한국생물물리학회:학술대회논문집
• /
• 한국생물물리학회 2003년도 정기총회 및 학술발표회
• /
• pp.29-29
• /
• 2003

Compartmentation of intracellular signaling pathways serves as an important mechanism conferring the specificity of G protein-coupled receptor (GPCR) signaling. In the heart, stimulation of $\beta$$_2$-adrenoceptor ($\beta$$_2$-AR), a prototypical GPCR, activates a tightly localized protein kinase A (PKA) signaling, which regulates substrates at cell surface membranes, bypassing cytosolic target proteins (eg, phospholamban). Although a concurrent activation of $\beta$$_2$-AR-coupled $G_{i}$ proteins has been implicated in the functional compartmentation of PKA signaling, the exact mechanism underlying the restriction of the $\beta$$_2$-AR-PKA pathway remains unclear. In the present study, we demonstrate that phosphatidylinositol 3-kinase (PI3K) plays an essential role in confining the $\beta$$_2$-AR-PKA signaling. Inhibition of PI3K with LY294002 or wortmannin enables $\beta$$_2$-AR-PKA signaling to reach intracellular substrates, as manifested by a robust increase in phosphorylation of phospholamban, and markedly enhances the receptor-mediated positive contractile and relaxant responses in cardiac myocytes. These potentiating effects of PI3K inhibitors are not accompanied by an increase in $\beta$$_2$-AR-induced cAMP formation. Blocking $G_{i}$ or $G_{$\square$$\square$}$ signaling with pertussis toxin or $\beta$ARK-ct, a peptide inhibitor of $G_{$\square$$\square$}$, completely prevents the potentiating effects induced by PI3K inhibition, indicating that the pathway responsible for the functional compartmentation of $\beta$$_2$-AR-PKA siglaling sequentially involves $G_{i}$, $G_{$\square$$\square$}$, and PI3K. Thus, PI3K constitutes a key downstream event of $\beta$$_2$-AR- $G_{i}$ signaling, which confines and negates the concurrent $\beta$$_2$-AR/Gs-mediated PKA signaling.gnaling.

• 대한약리학회지
• /
• 제2권1호
• /
• pp.41-48
• /
• 1966

The author studied the adrenotropic receptors of the non-pregnant uteri of the rabbit and rat, using epinephrine (alpha and beta activator), phenoxybenzamine(alpha blocking agent) and nethalide (beta blockade), and obtained the following results: 1. The spontaneous motility of isolated non-pregnant uteri from rabbits were stimulated by epinephrine, whereas that of isolated non-pregnant rat uterus was inhibited by epinephrine. 2. Both alpha and beta adrenergic receptors were present in the uterine muscle of both animals. 3. In the non-pregnant rabbit uterus, alpha receptors were predominant, whereas in the non -pregnant rat uterus, beta receptors preponderated over alpha receptors.

• Bulletin of the Korean Chemical Society
• /
• 제32권6호
• /
• pp.2008-2014
• /
• 2011

Serotonin or 5-hydroxytryptamine subtype 2C ($5-HT_{2C}$) receptor belongs to class A amine subfamily of G-protein-coupled receptor (GPCR) super family and its ligands has therapeutic promise as anti-depressant and -obesity agents. So far, bovine rhodopsin from class A opsin subfamily was the mostly used X-ray crystal template to model this receptor. Here, we explained homology model using beta 2 adrenergic receptor (${\beta}$2AR), the model was energetically minimized and validated by flexible ligand docking with known agonists and antagonists. In the active site Asp134, Ser138 of transmembrane 3 (TM3), Arg195 of extracellular loop 2 (ECL2) and Tyr358 of TM7 were found as important residues to interact with agonists. In addition to these, V208 of ECL2 and N351 of TM7 was found to interact with antagonists. Several conserved residues including Trp324, Phe327 and Phe328 were also found to contribute hydrophobic interaction. The predicted ligand binding mode is in good agreement with published mutagenesis and homology model data. This new template derived homology model can be useful for further virtual screening based lead identification.

• 대한수의학회지
• /
• 제34권3호
• /
• pp.493-500
• /
• 1994

The purpose of this study was to investigate the effects of neurotransmitters and the source of $Ca^{2+}$ in the effects of neurotransmitters on the motility of pig oviductal isthmic smooth muscle. The motility of the isolated smooth muscle was recorded by using physiological recording system. The results were summarized as follows; Acetylcholine, norepinephrine, histamine and prostaglandin $F_{2{\alpha}}(PGF_{2{\alpha}})$ caused the contraction and the contractile responses were increased in a dose-dependent manner from the concentration of $10^{-7}$ to $10^{-4}M$. The maximum contractility of acetylcholine, norepinephrine, histamine and $PGF_{2{\alpha}}$ was 65.99, 28.66, 83.99 and 47.33% of 100 mM K contraction, respectively. The contractile response induced by acetylcholine$(10^{-6}M)$ was completely blocked by the pretreatment with cholinergic receptor blocker, atropine$(10^{-6}M)$, the contractile response induced by norepinephrine$(10^{-5}M)$ was blocked by the pretreatment with ${\alpha}$-adrenergic receptor blocker, phentolamine$(10^{-6}M)$ but was not blocked and rather increased by the pretreatment with ${\beta}$-adrenergic receptor blocker. propranolol$(10^{-6}M)$, the contractile response induced by histamine$(10^{-6}M)$ was completely blocked by the pretreatment with $H_1$-histaminergic receptor blocker, pyrilamine$(10^{-6}M)$ but was increased by the pretreatment with $H_2$-histaminergic receptor blocker, cimetidine$(10^{-6}M)$. The contractile response induced by acetylcholine$(10^{-6}M)$, norepinephrine$(10^{-5}M)$ and histamine$(10^{-6}M)$ was weakly contracted response in $Ca^{2+}$-free medium, but the contractile response induced by $PGF_{2{\alpha}}(10^{-6}M)$ was disappeared. The contractile response induced by acetylcholine$(10^{-6}M)$, norepinephrine$(10^{-5}M)$ and histamine$(10^{-6}M)$ was powerfully depressed by the pretreatment with $Ca^{2+}$-channel blocker, verapamil$(10^{-5}M)$ but the contractile response induced by $PGF_{2{\alpha}}(10^{-6}M)$ was completely inhibited.

• Clinical and Experimental Pediatrics
• /
• 제48권6호
• /
• pp.580-587
• /
• 2005

New evidence is emerging that airway smooth muscle(ASM) may act as an immunomodulatory cell by providing pro-inflammatory cytokines and chemokines, polypeptide growth factors, extracellular matrix proteins, cell adhesion receptors and co-stimulatory molecules. ASM can promote the formation of the interstitial extracellular matrix, and potentially contribute to the alterations within the extracellular matrix in asthma. In addition, extracellular matrix components can alter the proliferative, survival, and cytoskeletal synthetic function of ASM cells through integrin-directed signaling. Increased ASM mass is one of the most important features of the airway wall remodeling process in asthma. Three different mechanisms may contribute to the increased ASM mass : cell proliferation, increased migration and decreased rate of apoptosis. The major signaling pathways of cell proliferation activated by ASM mitogens are those dependent on extracellular signal-regulated kinase and phosphoinositide 3'-kinase. The key signaling mechanisms of cell migration have been identified as the p38 mitogen-activated protein kinase and the p21-activated kinase 1 pathways. ASM cells contain ${\beta}2$-adrenergic receptors and glucocorticoid receptors. They may represent a key target for ${\beta}2$-adrenergic receptor agonist/corticosteroid interactions which have antiproliferative activity against a broad spectrum of mitogens.

• BMB Reports
• /
• 제31권2호
• /
• pp.123-129
• /
• 1998

Foreign proteins, $endo-{\beta}-1,4-glucanase$ of Bacillus subtilis, preS1+S2 region of hepatitis B virus large surface antigen, human ${\beta}_2-adrenergic$ receptor ($h{\beta}_{2}AR$), and bovine growth hormone (bGH) were expressed in Saccharomyces cerevisiae and secreted into the medium. These proteins were expressed using the alcohol dehydrogenase I (ADH1) promoter of Saccharomyces cerevisiae and secreted by signal sequence of the 97 K killer toxin gene of doublestranded linear DNA plasmid (pGKL1) of S. cerevisiae. All these proteins underwent severe modifications; in particular, N-glycosylation in the case of $endo-{\beta}-1,4-glucanase$, $h{\beta}_2AR$, and preS1+S2. Seventy four percent of the expressed $endo-{\beta}-1,4-glucanase$ was secreted into the culture medium. Highly modified proteins were detected in the culture medium and in the cell. Expressed $h{\beta}_2AR$, which has seven transmembrane domains, remained in the cell. The degrees of secretion and modification and the states of proteins in the culture medium and in the cell were quite different. These results indicated that the nature of the protein has a critical role in its secretion and modifications.

• 한국식품영양과학회지
• /
• 제33권1호
• /
• pp.83-90
• /
• 2004

한국인 남녀 530명을 대상으로 $\beta$3-AR의 유전자 다형성이 비만과 혈당의 증가에 미치는 영향을 연구한 결과 연구대상자들의 평균 연령은 26.55$\pm$0.31세이었고, 남성이 9.1%,여성이 90.9%이었다. $\beta$3-AR의 유전자 다형성의 분포는 WW형 0.75, WR형 0.22, RR형 0.03이었고, BMI 25 kg/$m^2$를 기준으로 하여 정상군에서 WW, WR, RR형의 빈도수는 각각0.75, 0.23, 0.02이었고, 비만군에서는 각각 0.76, 0.21, 0.03이었다. 유전자 다형성에 따라 혈당은 WR＋RR형에서 WW형에 비해 유의적으로 증가하였다(p=0.001). 혈당 6.105 mmol/L을 기준으로 $\beta$3-AR의 유전자 다형성의 빈도수를 분석한 결과 WR＋RR형의 빈도수가 고혈당군에서는 35.6%이었고 정상혈당군에서는 23.3%으로 변이형의 빈도가 고혈당군에서 유의적으로 높았다(p=0.011). 혈당에 따라 비만도와 체지방율은 고혈당군에서 유의적으로 증가하였다(p=0.044, 0.046). HDL 콜레스테롤은 정상혈당군에서 유의적으로 증가하였고(p=0.006), 중성지방은 고혈당군에서 유의적으로 증가하였다(p=0.000). 혈당의 증가에 가장 영향을 미치는 지표를 분석하기 위해 다단계 로지스틱 회귀분석한 결과 중성지방(p=0.000), 혈중 알부민(p=0.008), $\beta$3-AR의 유전자 다형성 (p=0.011), HDL 콜레스테롤(p=0.059) 순으로 나타났다. 특히 중성지방의 증가와 $\beta$3-AR의 유전자의 WR＋RR형은 고혈당의 유발 위험율을 각각 2.165배, 2.015배 증가시키고, HDL 콜레스테롤의 증가는 위험율을 0.491배 감소시키는 결과를 보인다. 각각의 유전자다형성 군에서 혈당과 BMI, WHR, 체지방량의 상관성을 분석한 결과에서 정상군에서는 비만의 판정지표인 BMI, WHR, 체지방량과 혈당이 유의적인 정의 상관관계를 나타내었으나 변이형인 WR, RR형에서는 이들 변수간에 상관성이 보이지 않았다 결과적으로 $\beta$3-AR 유전자의 변이형에서 혈당은 증가하였고, 고혈당에서는 체지방 및 중성지방이 증가하였고, HDL 콜레스테롤은 감소하였다. 또한 고혈당과 변이형의 빈도는 유의적인 상관성을 나타내었다. 따라서 $\beta$3-AR 유전자의 변이형은 혈당과 혈중 지질의 조성변화에 영향을 미치며 이는 고혈당의 위험성을 예견할 수 있는 독립적인 지표로 나타났다.

• 대한약리학회지
• /
• 제11권2호
• /
• pp.9-17
• /
• 1975

The adrenergic blocking activity and refractory period of cardiac muscle on isolated rabbit atria were measured after administration of Scutellaria. In rabbits and cats the antiarrhythmic action of Scutellaria on atrial and ventricular arrhythmias produced by epinephrine or ouabain was examined and also compared with that of propranolol and quinidine. The alcoholic extract of Scutellaria produced a marked decrease in heart rate and contractile amplitude of the isolated rabbit atria. Pretreatment with Scutellaria rendered the atria to fail to respond to epinephrine, indicating that this crude drug possesses an adrenergic blocking activity. The extract produced a marked prolongation of the refractory period of atrial muscle. The extract effectively abolished the spontaneous arrhythmia occurring in the isolated rabbit atria. As propranolol and quinidine it also suppressed the atrial arrhythmia induced by ouabain. The extract prevented, as propranolol and quinidine, the induction of ventricular arrhythmia arising from excessive dose of epinephrine in anesthetized rabbits and cats. With regard to the ventricular arrhythmia induced by a continuous infusion of ouabain, the alcoholic extract of Scutellaria exerted some suppressive effect in anesthetized rabbits but no effect on cats. From the above results, it may be concluded that Scutellaria is effective against atrial and ventricular arrhythmias. The antiarrhythmic effects of this drug may be the result of adrenergic beta receptor blocking and cardiac depressive activities including prolongation of the refractory period of cardiac muscle.

• 대한약리학회지
• /
• 제16권2호
• /
• pp.25-29
• /
• 1980

Etomidoline ($Nonspa^{\circledR}$), which is chemically related to tertiary amine, is new synthetic antispasmodic agent with analgesic action. Antispasmodic effect of this agent is stronger than hyoscine butylbromide ($Buscopan^{\circledR}$), quaternary amine, and the absorption from intestine is also much higher. This study was undertaken to determine the effect of etomidoline on duodenal motility and other smooth muscles of rabbit. Strips of various isolated smooth muscle, 2 cm long from adult rabbits weighting about 2 kg, were suspended in a muscle chamber containing Tyrode's solution, which was bubbled with oxygen gas, and the temperature of the solution was kept constant at $38^{\circ}C$. After being washed with fresh solution several times the strips of smooth muscle attained constant motility and tonus. Etomidoline and other drugs were added in various concentrations to the chamber. Contractility of the strips was measured by using polygraph (Grass, model 7). The results are as follows: 1) In isolated rabbit atrium etomidoline produces a slight depression of contractility and the rate is also decreased. 2) On the other hand, etomidoline relaxed isolated strips of stomach, duodenal, and detrusor of rabbit. This relaxing effect of etomidoline on isolated duodenal strip of rabbit was not blocked by ${\alpha}$-adrenergic blocking agent, phenoxybenzamine, but by ${\beta}$-adrenergic blocking agent, propranolol. 3) Etomidoline did not exert any effect on isolated aorta, gall bladder, and trigone of rabbit. From the above results, it may be concluded that the relaxing effect of etomidoline on duodenal strip is related ${\beta}$-adrenergic receptor.

• 대한약리학회지
• /
• 제3권1호
• /
• pp.43-49
• /
• 1967

Supplemental studies were made on the adrenotropic receptors of the rat uterus, using adrenergic activators such as phenylephrine, norepinephrine, epinephrine, and isoproterenol and adrenergic blocking agents such as phenoxybenzamine and inderal. The studies have revealed the following results : 1. Phenylephrine, norepinephrine, epinephrine, and isoproterenol inhibited the spontaneous motility of the isolated rat uterus in the following order : Isoproterenol>epinephrine>norepinephrine>phenylephrine. 2. The inhibitory responses of the isolated rat uterus to phenylephrine and epinephrine were abolished by the pretreatment with phenoxybenzamine. 3. The inhibitory responses of the isolated rat uterus to isoproterenol and epinephrine were not affected by phenoxybenzamine. 4. The motility of the isolated rat uterus pretreated with inderal was stimulated by phenylephrine, norepinephrine and epinephrine. 5. The inhibitory responses of the isolated rat uterus to isoproterenol were abolished by the pretreatment with inderal. 6. The motility of the isolated rat uterus pretreated with inderal and phenoxybenzamine was not affected by phenylephrine, norepinephrine and epinephrine. 7. It is, therefore, concluded that the rat uterus has both alpha excitatory and beta inhibitory receptors, with beta inhibitory receptors predominating.