β adrenergic receptor

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].

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]

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].

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]

1. The metabolism of isoprenaline has been studied in man and dog following intravenous and oral or intra-duodenal administration.2. Intravenous isoprenaline was excreted largely unchanged in urine in both species. Only one-third of the radioactivity in urine was in the form of the O-methyl metabolite.3. After oral doses in man or intraduodenal doses in dogs, plasma radioactivity was almost entirely as conjugated isoprenaline and this metabolite accounted for more than 80% of radioactivity in urine.4. Catechol-O-methyl transferase may be less important than Uptake(2) in limiting the pharmacological action of isoprenaline.5. Pharmacological response (heart-rate increase) was related to plasma concentration of isoprenaline only after rapid intravenous injections. In dogs, following prolonged infusion or intraduodenal doses, heart rate returned to base-line values when plasma concentrations of isoprenaline were high.[6]

rat LD50 oral 2221 mg/kg Toxicology and Applied Pharmacology., 18(185), 1971 [PMID:5542824]
rat LD50 intraperitoneal 128 mg/kg Toksikologicheskii Vestnik., (5)(40), 1995
rat LD50 subcutaneous 600 ug/kg Fundamental and Applied Toxicology., 1(443), 1981
rat LD50 intravenous 26900 ug/kg SENSE ORGANS AND SPECIAL SENSES: LACRIMATION: EYE; BEHAVIORAL: CONVULSIONS OR EFFECT ON SEIZURE THRESHOLD; LUNGS, THORAX, OR RESPIRATION: RESPIRATORY STIMULATION Yakuri to Chiryo. Pharmacology and Therapeutics., 7(627), 1979
mouse LD50 oral 1260 mg/kg Drugs in Japan, -(119), 1990

[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. Slightly bitter taste. Aqueous solutions turn brownish-pink upon prolonged exposure to air. (NTP, 1992)
DL-Isoprenaline hydrochloride is a member of catechols.
Isoproterenol Hydrochloride is the hydrochloride salt form of isoproterenol, a synthetic catechol compound and potent beta adrenergic agonist with peripheral vasodilator, bronchodilator, and cardiac stimulating properties. Isoproterenol exerts its effect on the beta-1 adrenergic receptors in the myocardium, thereby increasing heart rate and cardiac output. In addition, isoproterenol acts on beta-2 adrenergic receptors in bronchiolar and vascular smooth muscle, thereby causing smooth muscle relaxation.
Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.
See also: Isoproterenol (has active moiety); Acetylcysteine; isoproterenol hydrochloride (component of) ... View More ...

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.)