IDENTIFICATION OF beta-LIKE ADRENOCEPTORS ASSOCIATED WITH BIOLUMINESCENCE IN THE SEA PANSY RENILLA KOELLIKERI

1993 ◽  
Vol 177 (1) ◽  
pp. 181-200 ◽  
Author(s):  
E. W. Awad ◽  
M. Anctil
Keyword(s):  
Radioligand Binding ◽  
Beta Blockers ◽  
Physiological Effect ◽  
The Body ◽  
Receptor Subtypes ◽  
Beta Adrenergic ◽  
Adrenergic Agents ◽  
Beta Agonists ◽  
Specificity Pattern ◽  
Renilla Koellikeri

Previous studies have reported pharmacological and biochemical evidence for the involvement of adrenergic substances in the regulation of neuroeffector activities in the bioluminescent cnidarian Renilla koellikeri (Cnidaria, Anthozoa). Therefore, direct radiobinding assays were developed to identify and characterize beta-adrenergic binding in membrane preparations from this species, using the two beta-antagonists [3H]dihydroalprenolol and [3H]CGP12177 as tracers. In addition, the effect of various beta-adrenergic agents on luminescence was examined. Binding of the radioligands at 25°C was rapid, reversible, saturable and specific. Saturation studies revealed the presence of two different and independent classes of binding site, site1 and site2, in the body of the colony (rachis). In contrast, homogeneous populations of binding sites corresponding to site1 were detected in autozooid polyps and to site2 in the peduncle. The pharmacological profile of beta-adrenergic binding in R. koellikeri membrane preparations displayed properties consistent with the presence of two sites and followed a pattern similar to beta2- and beta1-adrenergic receptor subtypes for site1 and site2, respectively. Bioluminescence in polyps was induced by beta-agonists as well as by one beta1-selective antagonist, atenolol, and was blocked by several beta-blockers including (+/−)CGP12177. The specificity pattern of the physiological effect of beta-adrenergic drugs on luminescence mirrors that of the radioligand interaction with site1. This suggests that radioligand binding to site1 represents binding to the receptor that mediates luminescence excitation in R. koellikeri. Blockade of the luminescent responses to site1 agonists by isotonic MgCl2 indicates that this beta-adrenergic mechanism must rely on interneuronal transmission. Collectively, these results suggest the evolutionary conservation of beta-adrenoceptors and of their dual character from coelenterates to higher vertebrates.

Positive coupling of beta-like adrenergic receptors with adenylate cyclase in the cnidarian Renilla koellikeri

1993 ◽  
Vol 182 (1) ◽  
pp. 131-146 ◽  
Author(s):  
E. W. Awad ◽  
M. Anctil
Keyword(s):  
Adenylate Cyclase ◽  
G Protein ◽  
Radioligand Binding ◽  
Guanine Nucleotides ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Binding Studies ◽  
Beta Adrenergic ◽  
Renilla Koellikeri ◽  
Stimulation Of

Coupling of the previously characterized beta1- and beta2-like adrenoceptors in the sea pansy Renilla koellikeri with adenylate cyclase was examined in membrane preparations from this cnidarian. Adenylate cyclase activity was stimulated by several guanine nucleotides, such as GTP, Gpp(NH)p and GTPgammaS. Fluoride ions and cholera toxin greatly enhanced the enzyme activity, whereas forskolin had no effect on basal or isoproterenol-induced stimulation of the enzyme. The stimulation of adenylate cyclase activity by several beta-adrenergic agonists in different parts of the animal reflected a positive coupling with the beta2- and beta1-like adrenoceptors in autozooid and peduncle tissues, respectively. In addition, isoproterenol-induced stimulation of adenylate cyclase activity was dependent on guanine nucleotides, suggesting coupling mediated by a G protein. The pharmacological profile of various antagonists on isoproterenol-sensitive adenylate cyclase in autozooid and peduncle tissues matched that of previous radioligand binding studies. Isoproterenol-induced stimulation of adenylate cyclase activity in rachidial tissues was partially inhibited by trifluoperazine of (+/−)CGP12177 and was completely blocked in the presence of both antagonists. This suggests that coupling of the enzyme occurs with beta1- and beta2-like adrenoceptors, both being present in the rachis. Serotonin and dopamine were also found to stimulate adenylate cyclase activity. Their stimulatory effect was additive to isoproterenol-induced activation, suggesting the presence of dopaminergic and serotonergic receptors in the tissues of the sea pansy. Along with the data presented previously on beta-adrenergic binding, this study suggests that elements of receptor-dependent G protein signal transduction originated early in invertebrate evolution.

Molecular analysis of beta-adrenergic receptor subtypes in rat collecting duct: effects on cell cAMP and Ca2+ levels

1995 ◽  
Vol 268 (6) ◽  
pp. F1070-F1080 ◽  
Author(s):  
B. Mandon ◽  
E. Siga ◽  
A. Champigneulle ◽  
M. Imbert-Teboul ◽  
J. M. Elalouf
Keyword(s):  
Rank Order ◽  
Collecting Duct ◽  
Receptor Subtypes ◽  
Thick Ascending Limb ◽  
Camp Accumulation ◽  
Beta Adrenergic ◽  
Beta Agonists ◽  
Fluorescence Measurements ◽  
Beta 2 ◽  
Collecting Tubules

Expression and functional properties of beta-adrenergic receptors (beta-ARs) were studied in rat collecting tubules isolated by microdissection. Reverse transcription-polymerase chain reaction experiments demonstrated that the beta 1- and beta 2-AR mRNAs, but not the beta 3-subtype, are expressed in the cortical collecting duct (CCD). Quantitation of mRNAs, carried out using mutant RNAs as internal standards, further showed that beta 1- and beta 2-ARs transcripts are present at comparable amounts in CCD (3,000–4,000 copies/mm of tubular length), but reach 6–8 times lower levels in the outer medullary collecting duct (OMCD: beta 1, 480 +/- 180; beta 2, 590 +/- 110 copies/mm of tubular length). Functional studies, carried out in CCD, corroborated the expression of these two receptor subtypes. The rank order of potency of beta-agonists for stimulating adenosine 3',5'-cyclic monophosphate (cAMP) accumulation was isoproterenol > norepinephrine = epinephrine, and similar efficiencies were found for a beta 1- and a beta 2-antagonist to inhibit isoproterenol-dependent cAMP formation. Fura 2 fluorescence measurements revealed that isoproterenol (10 microM) induces a biphasic rise of intracellular free Ca2+ concentration ([Ca2+]i), consisting of an initial fast increase (delta [Ca2+]i = 122 nM) followed by a plateau phase (delta [Ca2+]i = 58 nM). In the absence of basolateral Ca2+, the initial peak was still observed, suggesting intracellular Ca2+ release. Norepinephrine and epinephrine, as well as selective beta 1- and beta 2-agonists, also increased [Ca2+]i in CCD. Only slight [Ca2+]i variations were produced by isoproterenol in the OMCD (delta [Ca2+]i = 21 nM) and the cortical thick ascending limb (delta [Ca2+]i = 25 nM). These results show that both beta 1- and beta 2-ARs are expressed in the collecting tubule and that they predominate in the CCD. The two receptor subtypes contribute to cAMP accumulation induced by beta-agonists. They also trigger [Ca2+]i variations, indicating their possible coupling to several transduction pathways in the rat CCD.

Beta-Adrenergic Agonists for Acute, Severe Asthma

1992 ◽  
Vol 26 (1) ◽  
pp. 81-91 ◽  
Author(s):  
H. William Kelly ◽  
Shirley Murphy
Keyword(s):  
Severe Asthma ◽  
Acute Asthma ◽  
The Body ◽  
Beta Agonist ◽  
Acute Severe Asthma ◽  
Adrenergic Agonists ◽  
Aerosol Delivery ◽  
Beta Adrenergic ◽  
Beta Agonists ◽  
Beta Adrenergic Agonists

OBJECTIVE: To critically review the use of beta-adrenergic agonists in acute, severe asthma with particular focus on aerosol administration. DATA SOURCES: English language articles published since 1971 on the use of beta-agonists for acute asthma. Studies were identified from bibliographies of book chapters, review articles, and other research articles. STUDY SELECTION: All studies (21 total) comparing systemic with inhaled beta-agonists were reviewed, regardless of their design or outcome. Selected studies highlighting specific aspects of beta-agonist use in acute asthma such as beta-agonists versus other bronchodilators, aerosol delivery, and intravenous beta-agonists were also reviewed. DATA EXTRACTION: Performed subjectively by the authors with specific aspects of quality discussed within the body of the article. DATA SYNTHESIS: The beta-agonists provide superior bronchodilation in acute severe asthma compared with either the methylxanthines and/or anticholinergics. The majority of studies found aerosolized beta-agonists to be either as effective as or more effective than parenteral beta-agonists and to produce fewer adverse cardiovascular effects. Studies showing preference for parenteral therapy have either been of poor design or used low doses of an aerosolized beta-agonist. Based on studies of aerosol delivery, there is no advantage of jet nebulization over metered-dose inhalers; however, other aspects, including ease of administration, favor nebulization as the delivery method of choice. The articles recommending intravenous beta-agonists consist of a series of uncontrolled cases. CONCLUSIONS: Aerosolized selective beta2-agonists are the bronchodilator treatments of choice for acute, severe asthma. Attention to the details of dosing and delivery are required for optimal results. The final dose and dosing interval are determined by the patient's response. Intravenous beta-agonists are hazardous and cannot be recommended.

Bronchospasmolytic and Adenosine Binding Activity of 8- (Proline / Pyrazole)-Substituted Xanthine Derivatives

2020 ◽  
Vol 17 ◽  
Author(s):  
Sneha Singh ◽  
Madhwi Ojha ◽  
Divya Yadav ◽  
Sonja Kachler ◽  
Karl-Norbert Klotz ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Radioligand Binding ◽  
Binding Activity ◽  
Receptor Subtypes ◽  
Significant Protection ◽  
Binding Studies ◽  
Standard Drug ◽  
Xanthine Derivatives ◽  
Radioligand Binding Studies ◽  
Micromolar Range

Background: ABSTRACT: Background: 8-Phenyltheophylline derivatives exhibit prophylactic effects at a specific dose but do not produce the cardiovascular or emetic side effects associated with xanthines, thereby exhibiting unique characteristics of potential therapeutic importance. Methods: Novel series of 8-(proline/pyrazole)-substituted xanthine analogs has been synthesized. The affinity and selectivity of compounds to adenosine receptors have been assessed by radioligand binding studies. The synthesized compounds also showed good bronchospasmolytic properties (increased onset of bronchospasm; decreased duration of jerks) with 100% survival of animals in comparison to the standard drug. Besides, compound 8f & 9f showed good binding affinity in comparison to other synthesized compounds in the micromolar range. Results: The maximum binding affinity of these compounds was observed for A2B receptors, which is ~ 7 or 10 times higher as compared to A1, A2A and A3 receptors. The newly synthesized derivatives 8f, 9a-f, 17g-m, and 18g-m displayed significant protection against histamine aerosol induced bronchospasm in guinea pigs. Conclusion: Newly synthesized proline/pyrazole based xanthines compounds showed a satisfactory binding affinity for adenosine receptor subtypes. Replacement or variation of substituted proline ring with substituted pyrazole scaffold at 8thposition of xanthine moiety resulted in the reduction of adenosine binding affinity and bronchospasmolytic effects.

Treatment with beta-blockers normalizes RyR2 phosphorylation and calcium spark activity in atrial myocytes from patients with atrial fibrillation

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
V Jimenez-Sabado ◽  
S Casabella ◽  
P Izquierdo ◽  
C Tarifa ◽  
A Llach ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Calcium Imaging ◽  
Adrenergic Receptors ◽  
Beta Blockers ◽  
Funding Source ◽  
Atrial Myocytes ◽  
Calcium Sparks ◽  
Beta Adrenergic ◽  
Calcium Spark ◽  
Confocal Calcium Imaging

Abstract Background Atrial fibrillation has been associated with an increase in ryanodine receptor (RyR2) phosphorylation and local calcium release (calcium sparks). Carvedilol, a nonselective beta-adrenergic receptor blocker also inhibits the cardiac ryanodine receptor (RyR2), but it has been suggested that the enantiomer R-carvedilol only inhibits RyR2 activity and hence has the potential to inhibit calcium sparks without affecting RyR2 phosphorylation. Purpose This study aimed to determine the ability of the enantiomers R- and S-carvedilol to reverse RyR2 phosphorylation at s2808 and calcium sparks induced by the β2-adrenergic agonist fenoterol, in order to determine the relationship between RyR2 phosphorylation at s2808 and calcium spark frequency, and to assess the efficacy of R- and S-carvedilol. Methods Human right atrial myocytes were isolated and subjected to immunofluorescent labelling of total and s2808 phosphorylated RyR2, or loaded with fluo-4 and subjected to confocal calcium imaging. Beta-adrenergic receptors were first activated with 3μM fenoterol and then inhibited by different concentrations of carvedilol R- or S-enantiomers. Results Incubation of myocytes with fenoterol increased the s2808/RyR2 ratio from 0.32±0.03 to 0.66±0.05 (n=18, p<0.001). Incubation with 0.1, 0.3, 1 or 3μM R-carvedilol in the presence of fenoterol changed the s2808/RyR2 ratio to 0.64±0.05, 0.44±0.04, 0.34±0.07 and 0.28±0.05 (p<0.01) respectively. For comparison 3μM S-carvedilol reduced the s2808/RyR2 ratio to 0.23±0.06 in myocytes from 5 patients (p<0.01). Confocal calcium imaging revealed that fenoterol increased the spark density from 0.28±0.04 to 1.24±0.25 events/s/1000μm2 (n=9, p<0.01) and addition of 0.1, 0.3, or 1μM R-carvedilol changed the frequency to 1.32±0.52, 0.38±0.05, and 0.15±0.05 events/s/1000μm2 (p<0.01) respectively. Analysis of atrial myocytes from patients without atrial fibrillation revealed that the s2808/RyR2 ratio was similar in 25 patients treated with beta-blockers (0.39±0.04) and 57 that did not receive beta-blockers (0.44±0.03, p=0.33) while the s2808/RyR2 ratio was significantly smaller in 16 patients with atrial fibrillation receiving beta-blockers (0.43±0.08) than in 5 patients that did not (0.80±0.19, p<0.05). Conclusions R-carvedilol reverses the effects of beta-adrenergic stimulation on s2808 phosphorylation and calcium sparks in human atrial myocytes, and treatment with beta-blockers reduces excessive RyR2 phosphorylation at s2808 in patients with atrial fibrillation to levels observed in those without the arrhythmia, pointing to beta-adrenergic receptors as a target for controlling RyR2 phophorylation and activity in atrial fibrillation. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Spanish Ministry of Science and Innovation & Spanish Ministry of Health and Consume

Pharmacologic responsiveness of isolated single eccrine sweat glands

1981 ◽  
Vol 240 (1) ◽  
pp. R44-R51 ◽  
Author(s):  
K. Sato ◽  
F. Sato
Keyword(s):  
Dose Response ◽  
Dissociation Constants ◽  
Sweat Rate ◽  
Sweat Glands ◽  
Adrenergic Agonist ◽  
Beta Adrenergic ◽  
Adrenergic Agents ◽  
Eccrine Sweat Glands ◽  
Eccrine Sweat

Pharmacologic responsiveness of the eccrine sweat gland has never been studied under well-defined in vitro experimental conditions. Using isolated cannulated single monkey palm eccrine sweat glands, the dose response to both cholinergic and alpha- and beta-adrenergic agents and the effects of various antagonists on agonists were studied. The maximal sweat rate was highest after stimulation with cholinergic agonists, was lower with the beta-adrenergic agonist, and was least with the alpha-adrenergic agonist. Each secretory response was inhibited by its specific antagonist. Attempts to demonstrate the spare receptor, if any, by means of preincubation of the glands with N-(2-chlorethyl)dibenzylamine (Dibenamine) were unsuccessful. From the hyperbolic dose-response curves the values for KA and KB, dissociation constants for agonists and antagonists, respectively, were thus tentatively estimated according to Clark's classical receptor theory. Schild plots for each agonist-antagonist interaction produced straight lines with slopes of near unity, indicating the adequacy of the methodology. It was concluded that the isolated eccrine sweat glands retain their pharmacologic viability in vitro and show responsiveness to cholinergic as well as both alpha- and beta-adrenergic stimulations.

Abstract 588: Beta-blockers Reverse Beta Adrenergic Receptors Desensitization Under Hypoxia

2019 ◽  
Vol 125 (Suppl_1) ◽  
Author(s):  
Yu Sun ◽  
Manveen Gupta ◽  
Kate Stenson ◽  
Sathyamangla Prasad
Keyword(s):  
Adrenergic Receptors ◽  
Beta Blockers ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic
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