β2/1-adrenergic receptor

ICI-118551 blocks cAMP accumulation by 50% (IC50 = 1.7 mM)[1]. Pharmacological experiments demonstrate that ICI 118551's right shift of the norepinephrine dose-response curve is mediated via a beta(2)-adrenoceptor/G(i/o) protein-dependent pathway, which enhances NO production in the endothelium. These findings are supported by the fact that ICI 118551 has no effect on beta-adrenoceptor and endothelial NO synthase knockout mice. In the isolated perfused lung model, ICI 118551 lowers pulmonary arterial pressure both in hypoxic and normoxic conditions while increasing vascular lumen diameter in lung sections[2]. While transgenic mice with elevated G(i) levels and a high beta(2)AR number exhibit normal basal contractility, they also exhibit a similar negative inotropic response to ICI 118,551. The negative inotropic effect of ICI 118,551 is amplified by employing an adenovirus to overexpress human beta(2)AR in rabbit myocytes. Following treatment of cells with pertussis toxin to inactivate G(i), the negative inotropic effects are blocked in human, rabbit, and mouse myocytes. In normal rat myocytes, overexpression of G(i)alpha(2) induces the effect de novo[5].

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It is hypothesize that ICI 118,551 binding directs the beta(2)AR to a G(i)-coupled form and away from the G(s)-coupled form (ligand-directed trafficking). ICI 118,551 effectively acts as an agonist at the G(i)-coupled beta(2)AR, producing a direct negative inotropic effect. Conditions where beta(2)ARs are present and G(i) is raised (failing human heart, TGbeta(2) mouse heart) predispose to the appearance of the negative inotropic effect[5].

The beta 1-receptor mediated shortening of electromechanical systole (QS2I), rise in systolic pressure, and rise in renin are unaffected by ICI 118,551 after one week of treatment; however, these responses are inhibited by a dose factor of eight following propranolol. The beta 2-receptor-mediated rise in noradrenaline and fall in diastolic pressure are equally blocked by ICI 118,551 and propranolol. Blood pressure is lowered when ICI 118,551 selectively blocks beta 2[4].

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1. The effects of the selective beta 2-adrenoceptor antagonist ICI 118551 on essential tremor, heart rate and blood pressure were compared with those of propranolol. 2. ICI 118551 (150 mg daily for 7 days) and propranolol (120 mg daily for 7 days) were about equally effective in reducing essential tremor (by about 40%) and were more effective than placebo. 3. When compared with the effect of placebo, propranolol reduced blood pressure and exercise heart rate whereas ICI 118551 had no significant effect on blood pressure and produced a small but significant reduction in exercise-induced tachycardia. 4. ICI 118551 may be useful in the management of essential tremor while having fewer cardiovascular side-effects than non-selective beta-adrenoceptor antagonists.[2]

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The β(2) adrenergic receptor antagonist -(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol (ICI-118,551) (1 or 2 mg/kg i.p.) blocked reinstatement by forced swim or BRL-44,408, whereas administration of the nonselective β-adrenergic receptor agonist isoproterenol (2 or 4 mg/kg i.p.) or the β(2) adrenergic receptor-selective agonist clenbuterol (2 or 4 mg/kg i.p.) induced reinstatement. Forced swim-induced, but not BRL-44,408-induced, reinstatement was also blocked by a high (20 mg/kg) but not low (10 mg/kg) dose of the β(1) adrenergic receptor antagonist betaxolol, and isoproterenol-induced reinstatement was blocked by pretreatment with either ICI-118,551 or betaxolol, suggesting a potential cooperative role for β(1) and β(2) adrenergic receptors in stress-induced reinstatement. Overall, these findings suggest that targeting β-adrenergic receptors may represent a promising pharmacotherapeutic strategy for preventing drug relapse, particularly in cocaine addicts whose drug use is stress related.[3]

The growth media are taken out of the wells and replaced with 50 uL of Hanks' balanced salt solution an hour before the assay. This solution also included 0.5 mM of MgCl₂•6H₂O, 0.4 mM of MgSO₄•7H₂O, 20 mM of N-2-hydroxyethylpiperazine-N'-2ethanesulfonic acid (HEPES), 1.2 mM of 3-isobutyl-1-methylxanthine (IBMX), 0.95 mM of CaCl₂, and 0.05% of BSA. For dose-response studies, every plate is submerged in a shaking water bath at 37°C. In one study, five wells/dose/plate are added, and then 10 minutes are spent incubating different doses of isoproterenol (10^-9-10^-5 M) and β1- and β2-receptor-selective partial agonists (tazolol, prenalterol, salbutamol, and terbutaline, 10^-6 and 10^-5 M, respectively). Another study uses 10 μM isoproterenol to stimulate the cells, either with or without different doses of β-adrenoceptor antagonists. After 10 minutes, the incubations are stopped by adding 100 μL of 10% trichloroacetic acid (TCA), which results in a final TCA concentration of 5%. Samples are dehydrated at 80°C for an entire night before being resuspended in 50 mM sodium acetate buffer after TCA is extracted twice using H₂0-saturated ether. A radioimmunoassay kit is used to measure the CAMP content.

In order to perform binding reactions, 60 μg of membranes are incubated with Zenidolol (ICI-118551) at various concentrations and 10 nM [3H]dihydroalprenolol hydrochloride. The binding reactions are stopped by quickly filtering the mixture through glass fiber filters following a two-hour incubation period at room temperature. Then, using a liquid scintillation counter, the radioactivity in the filters is measured. The presence of 1 μM alprenolol is used to determine non-specific binding. GraphPad Prism is used to analyze binding data.

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Researchers have observed direct (noncatecholamine-blocking) negative inotropic effects of the selective beta(2)-adrenoceptor (AR) antagonist Zenidolol (ICI-118551) in myocytes from failing human ventricle. In this study we characterize the effect in parallel in human myocytes and in myocytes from animal models where beta(2)ARs or G(i) proteins are overexpressed.
Methods and results: Enzymatically isolated, superfused ventricular myocytes were exposed to betaAR agonists and antagonists/inverse agonists, and contraction amplitude was measured. ICI 118,551 decreased contraction in ventricular myocytes from failing human hearts by 45.3+/-4.1% (n=20 hearts/31 myocytes, P<0.001) but had little effect in nonfailing hearts (4.9+/-4%, n=5 myocytes/3 hearts). Effects were significantly larger in patients classified as end-stage. Transgenic mice with high beta(2)AR number and increased G(i) levels had normal basal contractility but showed a similar negative inotropic response to ICI 118,551. Overexpression of human beta(2)AR in rabbit myocytes using adenovirus potentiated the negative inotropic effect of ICI 118,551. In human, rabbit, and mouse myocytes, the negative inotropic effects were blocked after treatment of cells with pertussis toxin to inactivate G(i), and overexpression of G(i)alpha(2) induced the effect de novo in normal rat myocytes[5].

Adrenaline may increase noradrenaline release and enhance sympathetic pressor effects through activation of pre-synaptic beta 2-adrenoceptors. Conversely, blockade of beta 2-receptors could lead to a fall in blood pressure. To test this hypothesis we performed a double-blind placebo controlled crossover study in nine patients with mild hypertension, comparing the effects of the beta 2-selective blocker Zenidolol (ICI-118551), 50 mg t.i.d. with those of propranolol, 80 mg t.i.d. Two hours after the first dose of Zenidolol (ICI-118551) or propranolol, plasma noradrenaline and blood pressure remained unchanged while heart rate and renin were reduced. After 1 week, blood pressure was significantly reduced by both drugs. The beta 2-selectivity of ICI 118,551 was confirmed by isoprenaline infusion studies. After 1 week of treatment ICI 118,551 had no effect on the beta 1-receptor mediated shortening of electromechanical systole (QS2I), the rise in systolic pressure and rise in renin, whereas these responses were blocked by a dose factor of eight after propranolol. ICI 118,551 and propranolol equally blocked the beta 2-receptor mediated fall in diastolic pressure and the rise in noradrenaline. We conclude that beta 2-selective blockade by ICI 118,551 lowers blood pressure. This finding is compatible with a role of pre-synaptic beta 2-receptors in blood pressure control.[4]

[1]. Naunyn Schmiedebergs Arch Pharmacol. 2004 Feb;369(2):151-9.

[2]. Br J Clin Pharmacol. 1987 Dec;24(6):729-34.

[3].J Pharmacol Exp Ther. 2012 Aug;342(2):541-51.

[4]. J Hypertens Suppl. 1985 Dec;3(3):S247-9.

[5]. Circulation. 2002 May 28;105(21):2497-503.

[6]. PLoS One. 2013 Dec 5;8(12):e82164.

Although many β1 receptor antagonists and β2 receptor agonists have been used in drug therapy for many years, their pharmacological properties on all three known β-adrenergic receptor subtypes are not always well characterized. Therefore, this study aimed to provide a comparison of the binding properties of agonists (epinephrine, norepinephrine, isoproterenol, fenoterol, salbutamol, salmeterol, terbutaline, formoterol, brombutatol) and antagonists (propranolol, apravolol, atenolol, metoprolol, bisoprolol, carvedilol, indolol, BRL 37344, CGP 20712, SR 59230A, CGP 12177, ICI 118551) to the three human β-adrenergic receptor subtypes in the same cellular context. We constructed Chinese hamster ovary (CHO) cells that stably expressed the three β-adrenergic receptor subtypes at comparable levels. We characterized these receptor subtypes and analyzed the affinity of commonly used drugs and experimental compounds using competitive binding assays with the non-selective antagonist 125I-cyanoyindolol as a radioligand. Furthermore, we analyzed the β-receptor-mediated adenylate cyclase activity in the isolated membranes of these cell lines. The results showed that all compounds exhibited distinct selectivity and activity patterns on the three β-receptor subtypes. In particular, we identified several β2 or β3 receptor agonists that exhibited inverse agonist activity on other subtypes. Additionally, we discovered several β1 receptor antagonists with agonist activity on both β2 and β3 receptors. The specific mixed effects of agonists, antagonists, and inverse agonists of different β-adrenergic receptor (β-AR) subtypes may have significant implications for the therapeutic applications of the corresponding compounds. [1] β-adrenergic receptors (β-ARs) are typical G protein-coupled receptors that mediate signal transduction in the sympathetic nervous system. Although drugs targeting β-ARs have been widely used in clinical practice, the signaling pathways downstream of β-AR stimulation have not been fully elucidated. In this study, cell lysate microarray technology was used to analyze the phosphorylated protein signaling pathways downstream of β-AR from a macroscopic perspective. We monitored the changes in the phosphorylation status of 54 proteins over time after β-AR activation of mouse embryonic fibroblasts (MEFs). Under stimulation by the non-selective β-adrenergic receptor agonist isoproterenol, we observed previously reported phosphorylation events, such as ERK1/2 (T202/Y204) and CREB (S133), as well as some novel phosphorylation events, such as Cdc2 (Y15) and Pyk2 (Y402). All of these events were mediated by cAMP and PKA, as stimulation with the adenylate cyclase activator fosclin reproduced these events, while treatment with the PKA inhibitor H89 blocked them. Furthermore, we observed several novel protein dephosphorylation events in isoproterenol-induced PI3K/AKT pathway target substrates: GSK3β (S9), 4E-BP1 (S65), and p70s6k (T389). These dephosphorylations were cAMP-dependent but PKA-independent and associated with decreased PI3K/AKT activity. Isoproterenol stimulation also led to cAMP-dependent dephosphorylation of PP1α (T320), a modification known to be associated with enhanced activity of this phosphatase. The simultaneous occurrence of PP1α dephosphorylation with a secondary decrease in phosphorylation levels of certain PKA-phosphorylated substrates suggests that PP1α may be involved in a feedback loop to restore these phosphorylation levels to baseline. In summary, lysate microarrays are a powerful tool for analyzing phosphorylated protein signaling and provide a macroscopic perspective on how β-adrenergic receptor signaling regulates key pathways in cell growth and metabolism. [6]

C17H28CLNO2

313.86

313.18

C, 65.06; H, 8.99; Cl, 11.29; N, 4.46; O, 10.19

1217094-53-5

Zenidolol; 72795-26-7; 91021-57-7 (racemic); 72795-01-8; 72795-26-7

11957590

Typically exists as solid at room temperature

3

3

6

21

295

0

O(CC(C(C)NC(C)C)O)C1C=CC(C)=C2CCCC2=1.Cl

KBXMBGWSOLBOQM-UHFFFAOYSA-N

InChI=1S/C17H27NO2.ClH/c1-11(2)18-13(4)16(19)10-20-17-9-8-12(3)14-6-5-7-15(14)17;/h8-9,11,13,16,18-19H,5-7,10H2,1-4H3;1H

1-[(7-methyl-2,3-dihydro-1H-inden-4-yl)oxy]-3-(propan-2-ylamino)butan-2-ol;hydrochloride

1217094-53-5; ICI 118551 Hydrochloride; 1-[(7-methyl-2,3-dihydro-1H-inden-4-yl)oxy]-3-(propan-2-ylamino)butan-2-ol;hydrochloride; ICI 118,551 hydrochloride; (Rac)-ICI-118551 (hydrochloride); 72795-01-8; ICI-118551; 3-(isopropylamino)-1-((7-methyl-2,3-dihydro-1H-inden-4-yl)oxy)butan-2-ol hydrochloride;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)