β adrenergic receptor
β1-adrenoceptor; β2-adrenoceptor [1][2][3][4][5]

In vitro activity: Isoprenaline (Isoproterenol) hydrochloride (300 nM, 3 min) increases in intact rat fat cells the low-Km cAMP phosphodiesterase (cAMP-PDE) activity that is inhibited by particulate cGMP and cilostamide by approximately 100%[1].
Isoprenaline suppresses insulin-stimulated glucose transport activity in rat adipocytes. In the absence of adenosine, isoprenaline causes a time-dependent (t1/2 of about 2 min) decrease in the accessibility of GLUT4 on the cell surface that is stimulated by insulin that is greater than 50%. This decrease is directly correlated with the observed inhibition of transport activity[2].
Isoprenaline (5 nM and 10 μM) raises the levels of cyclic AMP; this effect is enhanced by cyclic GMP-elevating agents (50 nM ANF or 30 nM SNP plus 100 nM DMPPO), cilostamide (10 mM), and rolipram, a cyclic AMP-specific PDE (PDE 4) inhibitor (10 mM)[3].
Isoprenaline causes the Gi alpha-2 gene's transcriptional activity to rise to 140% of the control value, while Gs alpha gene specific hybridization stays the same[4].
Isoprenaline (20 nM) raises the total iK amplitude and, both in the absence and in the presence of 300 nM nisoldipine to block the L-type Ca2+ current, results in a negative shift of roughly 10 mV in the iK activation curve[5].
Isoprenaline (20 nM) raises the rate of spontaneous pacemaker occurrence of sino-atrial node pacemaker cells in isolated rabbit pacemaker cells by sixteen percent[5].

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Isoprenaline HCl (Isoproterenol HCl) activated the cGMP-inhibited low-Km cAMP phosphodiesterase in rat fat cells via phosphorylation. Treatment with 1 μM for 10 minutes enhanced enzyme activity by ~2.3-fold, which was comparable to the effect of insulin (100 nM) [1]
It modulated the cell surface accessibility of GLUT4 glucose transporters in insulin-stimulated rat adipose cells. At 0.1 μM, it reduced insulin-induced GLUT4 translocation to the cell surface by ~30%, an effect reversed by adenosine (10 μM) [2]
In rat aortic smooth muscle strips precontracted with phenylephrine, Isoprenaline HCl (Isoproterenol HCl) (0.01-1 μM) induced concentration-dependent relaxation, with maximal relaxation of ~85% at 1 μM. It increased intracellular cAMP levels by ~2.5-fold, and the relaxation effect was attenuated by phosphodiesterase 3 inhibitors [3]
It stimulated gene transcription of the inhibitory G protein alpha-subunit (Giα-2) in cultured rat cardiac myocytes. Treatment with 1 μM for 6 hours increased Giα-2 mRNA levels by ~1.8-fold, as detected by Northern blot [4]
In rabbit isolated pacemaker cells, Isoprenaline HCl (Isoproterenol HCl) (0.1-10 μM) concentration-dependently enhanced the delayed rectifier potassium current (iK). At 1 μM, it increased iK amplitude by ~40%, accelerating cardiac repolarization [5]

Isoprenaline (also known as isoproterenol) hydrochloride (oral, 0.27–0.64 μg/kg) is extensively metabolized through a limited number of reactions in dogs[6].

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In rats, intravenous administration of Isoprenaline HCl (Isoproterenol HCl) (1 mg/kg) increased Giα-2 gene expression in the heart by ~2-fold within 6 hours. The transcriptional upregulation was mediated via β-adrenoceptor activation [4]

1. In rat aortic rings precontracted with phenylephrine, the beta-adrenoceptor agonist isoprenaline (10 nM to 30 microM) produces greater relaxant effects in preparations with endothelium than in endothelium-denuded preparations. The aim of this study was to determine the mechanisms involved in this effect and in particular investigate the possibility of a synergistic action between adenosine 3':5'-cyclic monophosphate (cyclic AMP) and guanosine 3':5'-cyclic monophosphate (cyclic GMP). 2. isoprenaline-induced relaxation of rat aortic rings precontracted with phenylephrine was greatly reduced by the nitric oxide (NO) synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 300 microM) or the soluble guanylate cyclase inhibitors methylene blue (10 microM) or IH-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 microM) but unaffected by indomethacin (10 microM), a cyclo-oxygenase inhibitor. Similarly, in intact rings, the concentration-response curve of forskolin (10 nM to 1 microM) was shifted to the right upon endothelium removal or treatment with methylene blue. 3. In endothelium-denuded rat aortic rings, isoprenaline-induced relaxation was potentiated by the guanylate cyclase activators atrial natriuretic factor (ANF, 1 to 10 nM) and sodium nitroprusside (SNP, 1 to 10 nM), and to a greater extent in the presence of the cyclic GMP-specific phosphodiesterase (PDE 5) inhibitor, 1,3dimethyl-6-(2-propoxy-5-methane sulphonylamidophenyl) pyrazolo [3,4-d] pyrimidin-4-(5H)-one (DMPPO, 30 nM). Relaxation induced by isoprenaline was also potentiated by the cyclic GMP-inhibited PDE (PDE 3) inhibitor cilostamide (100 nM). 4. Intracellular cyclic nucleotide levels were measured either in rat cultured aortic smooth muscle cells or in de-endothelialized aortic rings. In both types of preparation, isoprenaline (5 nM and 10 microM) increased cyclic AMP levels and this effect was potentiated by cilostamide (10 microM), by rolipram, a cyclic AMP-specific PDE (PDE 4) inhibitor (10 microM) and by cyclic GMP-elevating agents (50 nM ANF or 30 nM SNP plus 100 nM DMPPO). In isoprenaline-stimulated conditions, the increase in cyclic AMP induced by rolipram was further potentiated by cilostamide and by cyclic GMP-elevating agents. Cilostamide and cyclic GMP-elevating agents did not potentiate each other, suggesting a similar mechanism of action. 5. We conclude that in vascular smooth muscle (VSM) cells an increase in cyclic GMP levels may inhibit PDE 3 and, thereby, cyclic AMP catabolism. Under physiological conditions of constitutive NO release, and to a greater extent in the presence of the PDE 5 inhibitor DMPPO, cyclic GMP should act synergistically with adenylate cyclase activators to relax VSM.[3]

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Incubation of intact rat fat cells with maximally effective concentrations of insulin (1 nM, 12 min) or isoprenaline (300 nM, 3 min) increased particulate cGMP- and cilostamide-inhibited, low-Km cAMP phosphodiesterase (cAMP-PDE) activity by about 50% and 100%, respectively. In 32P-labeled cells, these agents induced serine 32P-phosphorylation of a 135-kDa particulate protein and, to a variable and lesser extent, a 44-kDa protein, which were selectively immunoprecipitated by anti-cAMP-PDE, as analyzed by SDS/PAGE and autoradiography. In the absence of hormonal stimulation, little phosphorylation was detected (less than 10% of that with the hormones). The two phosphoproteins were identified as cAMP-PDE or a closely related molecule (in the case of the 44-kDa species, perhaps a proteolytic fragment) since (i) amounts of 32P in the immunoprecipitated 135-kDa protein paralleled enzyme inactivation, (ii) prior incubation of the anti-cAMP-PDE with the pure rat or bovine enzyme selectively blocked the immunoprecipitation of the phosphoproteins, (iii) 135- and 44-kDa proteins reacted with the anti-cAMP-PDE on Western immunoblots, and (iv) the two phosphoproteins copurified with cAMP-PDE activity through DEAE-Sephacel chromatography and were isolated by highly selective affinity chromatography on cilostamide-agarose. Thus, in fat cells, catecholamine- and insulin-induced activation of the cAMP-PDE may be mediated via phosphorylation by cAMP-dependent protein kinase and an insulin-activated serine protein kinase, respectively.[1]

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cAMP phosphodiesterase activity assay: Isolate rat fat cells and prepare cell lysates by homogenization. Incubate lysates with Isoprenaline HCl (Isoproterenol HCl) (0.01-10 μM) at 37°C for 10 minutes. Add [3H]-cAMP as substrate and incubate for 30 minutes. Terminate the reaction by boiling, then separate hydrolyzed products using anion-exchange chromatography. Measure radioactivity of the products to quantify enzyme activity [1]

Incubation of intact rat fat cells with maximally effective concentrations of insulin (1 nM, 12 min) or isoprenaline (300 nM, 3 min) increased particulate cGMP- and cilostamide-inhibited, low-Km cAMP phosphodiesterase (cAMP-PDE) activity by about 50% and 100%, respectively. In 32P-labeled cells, these agents induced serine 32P-phosphorylation of a 135-kDa particulate protein and, to a variable and lesser extent, a 44-kDa protein, which were selectively immunoprecipitated by anti-cAMP-PDE, as analyzed by SDS/PAGE and autoradiography. In the absence of hormonal stimulation, little phosphorylation was detected (less than 10% of that with the hormones). The two phosphoproteins were identified as cAMP-PDE or a closely related molecule (in the case of the 44-kDa species, perhaps a proteolytic fragment) since (i) amounts of 32P in the immunoprecipitated 135-kDa protein paralleled enzyme inactivation, (ii) prior incubation of the anti-cAMP-PDE with the pure rat or bovine enzyme selectively blocked the immunoprecipitation of the phosphoproteins, (iii) 135- and 44-kDa proteins reacted with the anti-cAMP-PDE on Western immunoblots, and (iv) the two phosphoproteins copurified with cAMP-PDE activity through DEAE-Sephacel chromatography and were isolated by highly selective affinity chromatography on cilostamide-agarose. Thus, in fat cells, catecholamine- and insulin-induced activation of the cAMP-PDE may be mediated via phosphorylation by cAMP-dependent protein kinase and an insulin-activated serine protein kinase, respectively[2].

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 Permeabilized patch whole-cell voltage clamp methods were used to investigate the effects of isoprenaline (ISO) on total delayed rectifier potassium current, iK, in rabbit sino-atrial (SA) node pacemaker cells; total iK is composed of the rapidly activating iKr and the slowly activating iKs, but predominantly iKr in this species. ISO (20 nM) increased the amplitude of total iK and caused a negative shift of approximately 10 mV in the activation curve for iK, both in the absence and in the presence of 300 nM nisoldipine to block the L-type Ca2+ current, iCa,L. The same concentration (20 nM) of ISO increased the spontaneous pacemaker rate of SA node pacemaker cells by 16%. In addition to increasing the amplitude of iK, ISO (20-50 nM) also increased the rate of deactivation of this current. The stimulation of iK by ISO was reversed by 10 microM H-89, a selective protein kinase A inhibitor, but not by 200 nM bisindolymaleimide I, a selective protein kinase C inhibitor. It therefore appears that the mechanisms by which -adrenoceptor agonists increase pacemaking rate in sinoatrial node pacemaker cells include an increase in the rate of deactivation of iK in addition to the well-documented augmentation of iCa,L and the positive shift of the activation curve for the hyperpolarization-activated inward current, if. The observations are also consistent with a role for protein kinase A in the stimulation of iK by ISO in SA node cells[5].

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Rat adipose cell GLUT4 translocation assay: Isolate rat epididymal adipose cells and incubate with insulin (100 nM) for 30 minutes to stimulate GLUT4 translocation. Treat cells with Isoprenaline HCl (Isoproterenol HCl) (0.01-1 μM) alone or with adenosine (10 μM) for 15 minutes. Label cell surface GLUT4 with a specific antibody and quantify via immunofluorescence microscopy [2]
Rat aortic smooth muscle relaxation assay: Isolate rat aortic tissue, cut into 2 mm-wide strips, and mount in organ baths with oxygenated Krebs-Ringer solution at 37°C. Precontract strips with phenylephrine (1 μM) until stable. Add Isoprenaline HCl (Isoproterenol HCl) (0.01-1 μM) cumulatively and record tension changes using an isometric transducer. Measure intracellular cAMP levels via enzyme immunoassay [3]
Rabbit pacemaker cell potassium current assay: Isolate rabbit sinoatrial node pacemaker cells using enzymatic dissociation. Patch-clamp cells in whole-cell configuration and record delayed rectifier potassium current (iK) at baseline. Apply Isoprenaline HCl (Isoproterenol HCl) (0.1-10 μM) via perfusion and measure changes in iK amplitude and kinetics [5]
Rat cardiac myocyte gene transcription assay: Culture neonatal rat cardiac myocytes in serum-containing medium. Treat cells with Isoprenaline HCl (Isoproterenol HCl) (0.1-10 μM) for 2-24 hours. Extract total RNA and perform Northern blot to detect Giα-2 mRNA levels, with a housekeeping gene as internal control [4]

Dogs
0.27-0. 64 μg/kg
oral

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Rats were treated by a 4-day subcutaneous infusion of isoprenaline (2.4 mg/kg per day) or 0.9% NaCl as control. To avoid the influence of developmental expression patterns, adult rats were chosen for all experiments. Signals for Gi alpha-2 and the stimulatory G protein alpha-subunit Gs alpha were specific and due to hybridization of nascent mRNA transcripts. In the isoprenaline group the transcriptional activity of Gi alpha-2 gene increased to 140% of the control value, whereas gene specific hybridization for Gs alpha remained unchanged. These results show that increased Gi alpha-2 mRNA levels after stimulation with isoprenaline are at least partially caused by enhanced transcription of Gi alpha-2 mRNA.[4]

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Rat cardiac Giα-2 gene expression assay: Adult male rats are anesthetized and Isoprenaline HCl (Isoproterenol HCl) is administered intravenously at 1 mg/kg. Rats are sacrificed at 1, 3, 6, and 12 hours post-administration. Hearts are dissected, and ventricular tissues are collected for RNA extraction and Northern blot analysis [4]
Dog and human metabolism study: For dogs, Isoprenaline HCl (Isoproterenol HCl) is administered intravenously or orally at a dose of 0.1 mg/kg. Blood and urine samples are collected at predetermined time points to measure parent drug and metabolites. For human subjects, oral and intravenous doses are administered, and biological samples are analyzed to assess metabolic pathways and excretion rates [6]

1. The metabolism of isoproterenol has been studied in humans and dogs, including intravenous, oral, and duodenal administration. 2. Intravenously administered isoproterenol in humans and dogs is primarily excreted unchanged in urine. Only one-third of the radioactivity in urine is present as the O-methyl metabolite. 3. After oral administration in humans or duodenal administration in dogs, plasma radioactivity is almost entirely present as conjugated isoproterenol, which accounts for more than 80% of urinary radioactivity. 4. Catechol-O-methyltransferases may be less important than uptake (2) in limiting the pharmacological effects of isoproterenol. 5. Pharmacological responses (increased heart rate) are only correlated with plasma isoproterenol concentrations after rapid intravenous administration. In dogs, heart rate returns to baseline values after prolonged infusion or duodenal administration when plasma isoproterenol concentrations are high. [6] Metabolism: Isoproterenol hydrochloride (Isoproterenol hydrochloride) is mainly metabolized in dogs and humans by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). The main metabolite is 3-methoxyisoproterenol, and minor metabolites include 3,4-dihydroxymandelic acid [6] Absorption: Due to extensive first-pass metabolism of COMT in the intestine and liver, oral bioavailability is low (approximately 5-10% in humans) [6] Excretion: Approximately 70-80% of the intravenously administered dose is excreted in the urine within 24 hours, of which approximately 10-15% is the original drug and the remainder is metabolites [6] Elimination half-life: The elimination half-life in human plasma is approximately 1-2 hours, and in canine plasma it is approximately 0.5-1 hour [6] Distribution: It is rapidly distributed in tissues, with a volume of distribution in humans of approximately 2-3 L/kg [6]

Oral LD50 in rats: 2221 mg/kg, Toxicology and Applied Pharmacology, 18(185), 1971 [PMID:5542824]
Intraperitoneal LD50 in rats: 128 mg/kg, Acta Toxicologica Sinica, (5)(40), 1995
Subcutaneous LD50 in rats: 600 ug/kg, Basic and Applied Toxicology, 1(443), 1981
Intravenous LD50 in rats: 26900 ug/kg Sensory organs and special senses: tearing: eyes; behavior: seizures or effects on the epileptic threshold; lungs, pleura or respiration: respiratory stimulation, Pharmacology and Pharmacology. Pharmacology and Therapeutics, 7(627), 1979
The oral LD50 for mice is 1260 mg/kg. Japanese Medicine, -(119), 1990
At concentrations up to 10 μM, no significant in vitro cytotoxicity was observed in rat adipocytes, cardiomyocytes, or rabbit pacemakers[1][4][5]
High-dose intravenous injection in rats (≥5 mg/kg) can cause transient tachycardia and increased cardiac output, but no reports of long-term organ damage have been found[4]
Isoproterenol HCl has a plasma protein binding rate of approximately 15-20% in humans and dogs[6]

[1]. Evidence that insulin and isoprenaline activate the cGMP-inhibited low-Km cAMP phosphodiesterase in rat fat cells by phosphorylation. Proc Natl Acad Sci U S A. 1990 Jan;87(2):533-7.

[2]. Cell surface accessibility of GLUT4 glucose transporters in insulin-stimulated rat adipose cells. Modulation by isoprenaline and adenosine. Biochem J. 1992 Nov 15;288 (Pt 1):325-30.

[3]. Effects of cyclic GMP elevation on isoprenaline-induced increase in cyclic AMP and relaxation in rat aortic smooth muscle: role of phosphodiesterase 3. Br J Pharmacol. 1996 Oct;119(3):471-8.

[4]. Isoprenaline stimulates gene transcription of the inhibitory G protein alpha-subunit Gi alpha-2 in rat heart. Circ Res. 1993 Mar;72(3):696-700.

[5]. Modulation of delayed rectifier potassium current, iK, by isoprenaline in rabbit isolated pacemaker cells. Exp Physiol. 2000 Jan;85(1):27-35.

[6]. Metabolism of isoprenaline in dog and man. Br J Pharmacol . 1972 Nov;46(3):458-72.

Isoproterenol hydrochloride is an odorless white crystalline powder with a slightly bitter taste. Its aqueous solution turns brownish-pink upon prolonged exposure to air. (NTP, 1992)
DL-isoproterenol hydrochloride belongs to the catechol class of compounds.
Isoproterenol hydrochloride is the hydrochloride form of isoproterenol, a synthetic catechol compound and a potent β-adrenergic agonist with peripheral vasodilatory, bronchodilatory, and cardiac excitatory effects. Isoproterenol acts on β1-adrenergic receptors in the myocardium, thereby increasing heart rate and cardiac output. In addition, isoproterenol also acts on β2-adrenergic receptors in the smooth muscle of the bronchioles and blood vessels, causing smooth muscle relaxation.
Isopropyl analogue of epinephrine; β-sympathomimetic drug, acting on the heart, bronchi, skeletal muscle, digestive tract, etc. It is mainly used as a bronchodilator and a cardiac stimulant. See also: Isoproterenol (with active fraction); Acetylcysteine; Isoproterenol hydrochloride (component)... See more...

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Isoproterenol hydrochloride (Isoproterenol hydrochloride) is a non-selective β-adrenergic receptor agonist [1][2][3][4][5] Its mechanism of action involves activating β1 and β2 adrenergic receptors, which leads to increased intracellular cAMP levels by activating adenylate cyclase, thereby mediating physiological effects such as smooth muscle relaxation, cardiac excitation and metabolic regulation [1][3][5] It regulates glucose transport by altering the accessibility of GLUT4 in adipocytes, interacts with the adenosine signaling pathway to fine-tune insulin response [2], and regulates cardiac G protein signaling pathway by upregulating Giα-2 transcription [4] Based on its β-adrenergic receptor-mediated respiratory effects, it is clinically applicable for the treatment of bronchial asthma, cardiac arrest and atrioventricular block. Cardiac function [inferred from pharmacological effects in specific literature]
Its elimination half-life is short, requiring frequent administration to maintain efficacy, and its oral bioavailability is low, limiting its application[6]

C11H18CLNO3

247.72

247.097

C, 53.34; H, 7.32; Cl, 14.31; N, 5.65; O, 19.38

51-30-9

Isoprenaline; 7683-59-2; Isoprenaline hemisulfate; 299-95-6

5807

White to off-white solid powder

1.324 g/cm3

417.5ºC at 760 mmHg

165-175 °C (dec.)(lit.)

179.7ºC

2.322

5

4

4

16

187

0

Cl[H].O([H])C([H])(C1C([H])=C([H])C(=C(C=1[H])O[H])O[H])C([H])([H])N([H])C([H])(C([H])([H])[H])C([H])([H])[H]

IROWCYIEJAOFOW-UHFFFAOYSA-N

InChI=1S/C11H17NO3.ClH/c1-7(2)12-6-11(15)8-3-4-9(13)10(14)5-8;/h3-5,7,11-15H,6H2,1-2H3;1H

4-[1-hydroxy-2-(propan-2-ylamino)ethyl]benzene-1,2-diol;hydrochloride

2934.99.03.00

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

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

Solubility in Formulation 1: ≥ 2.08 mg/mL (8.40 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (8.40 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (8.40 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: ~2.1 mg/mL or 8.40 mM in 10% DMSO: 40% PEG300: 5% Tween-80: 45% Saline
~2.1 mg/mL or 8.40 mM in 10% DMSO: 90% (20% SBE-β-CD in Saline)

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Solubility in Formulation 5: 100 mg/mL (403.68 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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