Alpha-adrenergic regulation of secretion by tracheal glands

1990 ◽  
Vol 259 (4) ◽  
pp. L198-L205 ◽  
Author(s):  
D. J. Culp ◽  
R. K. McBride ◽  
L. A. Graham ◽  
M. G. Marin
Keyword(s):  
Adrenergic Receptors ◽  
Specific Binding ◽  
Receptor Subtypes ◽  
Adrenergic Agonists ◽  
Beta Adrenergic ◽  
Adrenergic Regulation ◽  
Binding Characteristics ◽  
Low Concentrations ◽  
Adrenergic Antagonist ◽  
Uk 14,304

The purpose of the present study was to begin to characterize, pharmacologically, the alpha-adrenergic regulation of glycoconjugate secretion from airway glands. Using isolated gland cells from cat trachea, we determined the binding characteristics of [3H]dihydroergocryptine ([3H]DHE), an alpha-adrenergic antagonist, with equal affinities for alpha 1- and alpha 2-adrenergic receptors. Specific binding of [3H]DHE to gland cell homogenates was saturable, of high affinity (KDapp = 4.2 nM) and inhibited with greater efficacy by epinephrine much greater than isoproterenol. Competition experiments with alpha 1- and alpha 2-adrenergic selective antagonists (prazosin and yohimbine, respectively) demonstrated high- and low-affinity sites for each antagonist, indicating the presence of both receptor subtypes. In studies of glycoconjugate secretion by cat tracheal explants, secretion was stimulated by adrenergic agonists with the rank potency: norepinephrine greater than or equal to phenylephrine greater than epinephrine much greater than clonidine. alpha-Adrenergic-stimulated secretion (epinephrine + propranolol) was inhibited by low concentrations of prazosin, but was unaffected by 100 nM yohimbine. The alpha 2-adrenergic agonists, clonidine and UK-14,304, each markedly inhibited beta-adrenergic-stimulated secretion. Collectively, these results demonstrate alpha 1-adrenergic regulation of glandular glycoconjugate secretion and suggest alpha 2-adrenergic receptors may modulate beta-adrenergic-stimulated secretion.

scholarly journals Adrenergic and Cholinergic Receptors of Cerebral Microvessels

1981 ◽  
Vol 1 (3) ◽  
pp. 329-338 ◽  
Author(s):  
Sami I. Harik ◽  
Virendra K. Sharma ◽  
John R. Wetherbee ◽  
Robert H. Warren ◽  
Shailesh P. Banerjee
Keyword(s):  
Adrenergic Receptors ◽  
Specific Binding ◽  
Cholinergic Receptors ◽  
Biologically Active ◽  
Adrenergic Agonists ◽  
Muscarinic Cholinergic Receptors ◽  
Cerebral Microvessels ◽  
Binding Characteristics ◽  
Muscarinic Cholinergic ◽  
Β Adrenergic Receptors

The presence of α- and β-adrenergic and muscarinic cholinergic receptors in cerebral microvessels of the rat and pig was assessed by ligand binding techniques. The results demonstrate the presence of specific binding to α2- and β-adrenergic receptors but no appreciable specific binding to α1-adrenergic or muscarinic cholinergic receptors. β-Adrenergic receptors of pig cerebral microvessels are similar to those of the brain and other organs in their binding characteristics to the tritiated ligand and in their stereospecificity of binding to the biologically active isomers of β-adrenergic agonists. Further evidence derived from the differential potency of binding displacement by the various β-adrenergic agonists and selective β1- and β2-adrenergic antagonists indicates that β-adrenergic receptors of pig cerebral microvessels are mostly of the β2-subtype.

scholarly journals Localization of β-adrenergic receptors in A431 cells in situ. Effect of chronic exposure to agonist

1989 ◽  
Vol 263 (2) ◽  
pp. 533-538 ◽  
Author(s):  
H Y Wang ◽  
M Berrios ◽  
C C Malbon
Keyword(s):  
Adrenergic Receptors ◽  
High Speed ◽  
Radioligand Binding ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Beta Adrenergic Receptors ◽  
A431 Cells ◽  
Beta Adrenergic ◽  
Adrenergic Antagonist

The status of beta-adrenergic receptors was investigated in A431 cells exposed to chronic stimulation by the beta-adrenergic agonist, (-)-isoproterenol. Specific binding of beta-adrenergic antagonist (-)-[125I]iodocyanopindolol declined to 60-80% below control values within 12 h of agonist treatment. This decline in ligand binding was also observed in high-speed membrane fractions prepared from agonist-treated cells. Immunoblots probed with anti-receptor antibodies revealed both that beta-adrenergic receptors from untreated and treated cells migrated as 65,000-Mr peptides and that the cellular complement of receptor was unchanged. Indirect immunofluorescence localization of beta-adrenergic receptors was comparable in control (untreated) cells and cells challenged with (-)-isoproterenol for 1, 12, or 24 h. Thus receptor complement, migration on SDS/polyacrylamide-gel electrophoresis, and localization in situ are largely unaffected by agonist stimulation. Receptor binding of antagonist radioligands, in contrast, is markedly down-regulated in cells stimulated chronically with beta-adrenergic agonists. These data argue in favour of agonist-induced alteration(s) in the conformation of the receptor that preclude radioligand binding rather than agonist-induced receptor sequestration and/or degradation.

Hormonal regulation of hepatic glycogenolysis in the carp, Cyprinus carpio

1987 ◽  
Vol 252 (4) ◽  
pp. R653-R660 ◽  
Author(s):  
P. A. Janssens ◽  
P. Lowrey
Keyword(s):  
Cyprinus Carpio ◽  
Hormonal Regulation ◽  
Adrenergic Receptors ◽  
Specific Binding ◽  
Arginine Vasotocin ◽  
Dependent Manner ◽  
Beta Adrenergic ◽  
Alpha Adrenergic Receptors ◽  
Adrenergic Antagonist ◽  
Carp Cyprinus Carpio

Carp (Cyprinus carpio) liver maintained normal glycogen content and enzyme complement for several days in organ culture. Epinephrine-stimulated glycogenolysis, phosphorylase activation, and cyclic AMP (cAMP) accumulation in a concentration-dependent manner with EC50s of 100, 100, and 500 nM, respectively. These actions were blocked by the beta-adrenergic antagonist, propranolol, but not by the alpha-adrenergic antagonist phentolamine. Glycogenolysis and tissue cAMP were uninfluenced by 10(-6) M arginine vasotocin, arginine vasopressin, lysine vasotocin, lysine vasopressin, mesotocin, or oxytocin, but were slightly increased by 10(-5) M isotocin and slightly decreased by 10(-6) M angiotensin II. [125I]-iodocyanopindolol (ICP), a beta-adrenergic ligand, bound to isolated carp liver membranes with a KD of 83 pM. Maximum binding of 45 fmol/mg protein was at 600 pM. Propranolol, isoprenaline, epinephrine, phenylephrine, norepinephrine, and phenoxybenzamine displaced ICP with KDs of 100 nM, 2, 20, 20, 60, and 200 microM, respectively. The alpha-adrenergic antagonists, yohimbine and prazosin, showed no specific binding. These data provide evidence that catecholamines act via beta-adrenergic receptors in carp liver and that alpha-adrenergic receptors are not present. Vasoactive peptides play no significant role in regulation of carp liver glycogenolysis.

Alpha 2-receptors mediate catecholamine-stimulated acid secretion in Amphiuma jejunum

1988 ◽  
Vol 255 (5) ◽  
pp. G640-G646
Author(s):  
C. F. Hinton ◽  
J. F. White
Keyword(s):  
Acid Secretion ◽  
Basolateral Membrane ◽  
Adrenergic Agonists ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Ussing Chambers ◽  
Adrenergic Antagonist ◽  
Half Maximal Effective Concentration ◽  
Uk 14,304 ◽  
Stimulation Of

The receptors mediating adrenergic stimulation of acid secretion by Amphiuma jejunum were characterized in this study using alpha- and beta-adrenergic agonists and antagonists. Isolated segments of jejunum were mounted in Ussing chambers and bathed in Cl- -free (SO4(2-] medium. Shortcircuit current (Isc) and acid secretion (JH) were recorded, the latter by measuring the rate of alkalinization of the serosal medium. The beta-adrenergic receptor antagonist, propranolol (10(-4) M), had no effect on the Isc and JH stimulated by norepinephrine (NE). The alpha 2-adrenergic agonists, clonidine and UK-14,304, mimicked the effect of NE, with effective concentrations providing 50% maximal delta Isc of 2.0 X 10(-7) and 9.0 X 10(-8) M, respectively. NE added subsequently produced no greater stimulation. In contrast, the alpha 1-adrenergic agonists, phenylephrine and methoxamine, produced little stimulation of JH and Isc; NE added subsequently stimulated the Isc. The alpha 1-adrenergic antagonist prazosin had no effect on the NE-induced Isc or JH, whereas the alpha 2-adrenergic antagonist yohimbine inhibited the NE-stimulated Isc with a half-maximal effective concentration of 3.5 X 10(-7) M. Yohimbine (10(-4) M) reduced the NE-stimulated Isc by 88%, whereas the spontaneous Isc was reduced by only 12%. These results demonstrate that alpha 2-adrenergic receptors on the basolateral membrane of Amphiuma enterocytes mediate NE-enhanced, but not spontaneous, intestinal acid secretion.

Protein secretion in lacrimal gland: alpha 1-beta-adrenergic synergism

1986 ◽  
Vol 250 (5) ◽  
pp. C704-C712 ◽  
Author(s):  
P. Mauduit ◽  
G. Herman ◽  
B. Rossignol
Keyword(s):  
Binding Sites ◽  
Adrenergic Receptors ◽  
Specific Binding ◽  
Secretory Response ◽  
Receptor Subtype ◽  
Beta Adrenergic ◽  
Homogeneous Population ◽  
Specific Binding Sites ◽  
Adrenergic Antagonist ◽  
Simultaneous Activation

We have shown the existence of a homogeneous population of specific binding sites for [3H]prazosin in membranes from rat lacrimal glands. The value of the equilibrium dissociation constant was 0.186 +/- 0.07 nM, and the density of specific binding sites was 20.4 +/- 1 fmol/mg protein. Taking into account the potency sequences for adrenergic agonists and antagonists for competition with these [3H]prazosin binding sites, we identified them as alpha 1-adrenergic receptors. Moreover, we have demonstrated that the stimulation of protein discharge evoked by epinephrine could be partly attributed to the occupation of this alpha-adrenergic receptor subtype. However, the inhibition pattern of the epinephrine effect by a beta-adrenergic antagonist, 1-propranolol, and the characteristics of the secretory response observed when selectively stimulating the alpha 1- and beta-adrenergic receptors, either separately or simultaneously, suggest that 1) a simultaneous activation of both receptors is necessary to produce a maximal secretory response to catecholamines; and 2) a synergism may exist between these two routes of stimulation, leading to an amount of protein discharge higher than that expected in the case of additive effects.

Beta-adrenergic modulation of insulin binding in skeletal muscle

1986 ◽  
Vol 250 (2) ◽  
pp. E198-E204
Author(s):  
B. Webster ◽  
S. R. Vigna ◽  
T. Paquette ◽  
D. J. Koerker
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Protein Phosphatase ◽  
Adrenergic Receptors ◽  
Plasma Membranes ◽  
Acute Exercise ◽  
Insulin Binding ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic ◽  
Adrenergic Antagonist

Both a high physiological concentration (13.1 nM) of epinephrine (E) and acute exercise (AEx) have previously been shown to increase 125I-insulin binding in skeletal muscle. To investigate the site and mechanism of the effect of epinephrine on binding and the possible link between epinephrine- and AEx-enhanced insulin binding, we measured insulin binding in three different preparations: 1) crude membranes derived from whole soleus muscle incubated in vitro with 13.1 nM E, 2) crude membranes with E present in the binding assay, and 3) purified plasma membranes with E present. Epinephrine enhanced binding in all three preparations by 169, 144, and 164%, respectively, at low concentrations of insulin but had little effect at high concentrations. Epinephrine, therefore appears to have its effect at the plasma membrane. Propranolol (10 microM), a beta-adrenergic antagonist, blocked E-enhanced insulin binding and when added to crude membranes made from soleus and extensor digitorum longus muscle of AEx rats reversed the increase in binding seen with exercise. This indicates that E-enhanced insulin binding is mediated by beta-adrenergic receptors and that AEx enhances insulin binding via beta-adrenergic receptors. Sodium orthovanadate (3 mM), a phosphotyrosyl-protein phosphatase inhibitor, also inhibited the increase in insulin binding due to E, implying that E may increase insulin binding by activating a phosphotyrosyl-protein phosphatase which decreases the phosphorylation of a plasma membrane protein, presumably the insulin receptor.

scholarly journals Autoradiographic localization of beta-adrenoreceptors in rat uterus.

1988 ◽  
Vol 36 (12) ◽  
pp. 1475-1479 ◽  
Author(s):  
M Tolszczuk ◽  
G Pelletier
Keyword(s):  
Quantitative Estimation ◽  
Cell Types ◽  
Receptor Subtypes ◽  
High Concentration ◽  
Rat Uterus ◽  
Beta Adrenergic ◽  
Adrenergic Antagonist ◽  
Beta 2 ◽  
Different Cell Types

The inhibitory effects of catecholamines on uterine smooth muscle are known to be mediated through beta-adrenergic receptors. To investigate further the distribution of these receptors in the rat uterus, we utilized in vitro autoradiography using [125I]-cyanopindolol [CYP], a specific beta-receptor ligand that has equal activity for both beta 1- and beta 2-receptor subtypes. The specificity of the labeling and the characterization of receptor subtypes in different cell types were achieved by displacement of radioligand with increasing concentrations of zinterol, a beta-adrenergic agonist with preferential affinity for the beta 2-adrenoreceptor subtype, and practolol, a beta-adrenergic antagonist that binds preferentially to the beta 1-subtype. Quantitative estimation of ligand binding was performed by densitometry. It was shown that the vast majority of beta-adrenoreceptors were of the beta 2-subtype and were found in high concentration not only in the myometrium but also in the endometrial and serosal epithelia. Specific labeling was also observed in glandular elements. These results suggest that beta-adrenoreceptors might be involved in different functions in the uterus.

Potentiation of surfactant release in fetal lung by thyroid hormone action

1984 ◽  
Vol 56 (6) ◽  
pp. 1621-1626 ◽  
Author(s):  
D. K. Das ◽  
J. Ayromlooi ◽  
D. Bandyopadhyay ◽  
S. Bandyopadhyay ◽  
A. Neogi ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Adrenergic Receptors ◽  
Actinomycin D ◽  
Binding Capacity ◽  
Fetal Lung ◽  
Lavage Fluid ◽  
Beta Adrenergic Receptors ◽  
Lung Maturation ◽  
Beta Adrenergic ◽  
Adrenergic Antagonist

Thyroid hormone has been shown to accelerate fetal lung development, but the mechanisms by which this hormone acts are yet unknown. Since this hormone may act indirectly by potentiating the action of endogenous catecholamines, we studied this mechanism by measuring beta-adrenergic receptors in fetal lung. Fetal rabbits at 27 days of gestation were treated with triiodothyronine (T3), 100 micrograms/100 g, in the presence and absence of propranolol, 200 micrograms/100 g, or actinomycin D, 20 micrograms/100 g. Fetuses were killed by decapitation either after 4 or 24 h of T3 treatment. The beta-adrenergic antagonist l-[3H]dihydroalprenolol was used to directly estimate the number and affinity of beta-adrenergic receptor in lung membranes. T3 increased the number of beta-adrenergic receptors in fetal lung, but the affinity of binding did not change. The enhancement of binding capacity after 4 h of T3 treatment was not inhibited by actinomycin D. However, 24-h T3-mediated stimulation was partially blocked by actinomycin D. In addition, T3 stimulated the catecholamine content, adenylate cyclase activity, and adenosine 3′,5′-cyclic monophosphate content of lung. T3 increased the lecithin-to-sphingomyelin ratio, phosphatidylglycerol, and disaturated phosphatidylcholine content of the pulmonary lavage fluid. These parameters were completely inhibited by propranolol after 4 h and partially inhibited by actinomycin D after 24 h. Thus thyroid hormone enhances lung maturation by increasing the number of beta-adrenergic receptors in fetal lung.

Adrenal medullary regulation of rat renal cortical adrenergic receptors

1987 ◽  
Vol 253 (5) ◽  
pp. F1063-F1067
Author(s):  
P. R. Sundaresan ◽  
M. M. Guarnaccia ◽  
J. L. Izzo
Keyword(s):  
Adrenal Medulla ◽  
Adrenergic Receptors ◽  
Dissociation Constants ◽  
Specific Binding ◽  
Physiological State ◽  
Plasma Corticosterone ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic ◽  
Equilibrium Dissociation Constants ◽  
Equilibrium Dissociation

The role of the adrenal medulla in the regulation of renal cortical adrenergic receptors was investigated in renal cortical particulate fractions from control rats and rats 6 wk after adrenal demedullation. The specific binding of [3H]prazosin, [3H]rauwolscine, and [125I]iodocyanopindolol were used to quantitate alpha 1-, alpha 2-, and beta-adrenergic receptors, respectively. Adrenal demedullation increased the concentration of all three groups of renal adrenergic receptors; maximal number of binding sites (Bmax, per milligram membrane protein) for alpha 1-, and alpha 2-, and beta-adrenergic receptors were increased by 22, 18.5, and 25%, respectively (P less than 0.05 for each). No differences were found in the equilibrium dissociation constants (KD) for any of the radioligands. Plasma corticosterone and plasma and renal norepinephrine levels were unchanged, whereas plasma epinephrine was decreased 72% by adrenal demedullation (P less than 0.01); renal cortical epinephrine was not detectable in control or demedullated animals. Our results suggest that, in the physiological state, the adrenal medulla modulates the number of renal cortical adrenergic receptors, presumably through the actions of a circulating factor such as epinephrine.

Effects of some autonomic drugs on duodenal smooth muscle.

1979 ◽  
Vol 236 (1) ◽  
pp. E33
Author(s):  
S Anuras ◽  
D L Faulk ◽  
J Christensen
Keyword(s):  
Smooth Muscle ◽  
Adrenergic Receptors ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Adrenergic Agonists ◽  
Beta Adrenergic Receptors ◽  
Cholinergic Agonists ◽  
Beta Adrenergic ◽  
Alpha Adrenergic Receptors ◽  
Relative Potencies

Longitudinal muscle strips (LMS) and circular muscle strips (CMS), 2 mm wide and 1.5--2 cm long, from opossum duodenum were exposed to some autonomic agonists. The cholinergic agonists, acetylcholine, carbachol, methacholine, and bethanechol stimulated only tonic contractions in LMS and tonic followed by phasic contractions in CMS. These effects were abolished by atropine 10(-6) M. The ED50S of all cholinergic agonists for LMS were significantly lower than for CMS. Norepinephrine caused initial contraction (abolished by phenoxybenzamine, 10(-4) M), followed by relaxation (abolished by propranolol, 10(-5) M), and isopropylnorepinephrine caused relaxation (abolished by propranolol, 10(-5) M) in both layers. There were no differences in relative potencies for adrenergic agonists between the layers. Tetrodotoxin did not affect the response to adrenergic agonists. Thus, the potency of cholinergic agonists is greater in longitudinal than in circular muscle, and the layers respond differently to cholinergic agonists. The alpha-adrenergic receptors mediate contraction and beta-adrenergic receptors mediate relaxation on the duodenal smooth muscle.

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