scholarly journals Liver cell adenylate cyclase and beta-adrenergic receptors. Increased beta-adrenergic receptor number and responsiveness in the hypothyroid rat.

1980 ◽  
Vol 255 (18) ◽  
pp. 8692-8699 ◽  
Author(s):  
C.C. Malbon
Keyword(s):  
Adenylate Cyclase ◽  
Liver Cell ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Receptor Number

Beta-receptors and adenylate cyclase: comparison of nonischemic, ischemic, and postmortem tissue

1990 ◽  
Vol 258 (1) ◽  
pp. H140-H144 ◽  
Author(s):  
D. E. Vatner ◽  
M. A. Young ◽  
D. R. Knight ◽  
S. F. Vatner
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Striking Similarity ◽  
Receptor Density ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic

We compared the effects of myocardial ischemia and postmortem changes on beta-adrenergic receptors and their coupling to adenylate cyclase activity. The effects of 1 h of left circumflex coronary artery occlusion were examined in eight conscious calves, which were then anesthetized with pentobarbital sodium, and the left ventricle was divided into nonischemic and ischemic regions. A crude membrane fraction was prepared from each region and from the nonischemic tissue 1 h postmortem. beta-Adrenergic receptor density increased (152 +/- 55%) and decreases in basal (-21 +/- 6.1%), isoproterenol-stimulated (-25 +/- 8.0%), 5'-guanylylimidodiphosphate [Gpp(NH)p]-stimulated (-17 +/- 5.8%), fluoride-stimulated (-26 +/- 5.8%), and forskolin-stimulated (-31 +/- 8.4%) adenylate cyclase activities were observed in the ischemic myocardium compared with nonischemic myocardium. Similarly, in postmortem samples, beta-adrenergic receptor density rose 58 +/- 16%, whereas decreases in basal (-48 +/- 8.7%), isoproterenol-stimulated (-61 +/- 7.8%), Gpp(NH)p-stimulated (-58 +/- 7.0%), fluoride-stimulated (-64 +/- 6.1%), and forskolin-stimulated (-52 +/- 6.2%) adenylate cyclase activities were observed. Agonist-binding competition curves with isoproterenol were shifted, indicating that beta-adrenergic receptors were binding agonists with low affinity in both the ischemic and postmortem myocardium. The marked, but directionally opposite, changes in receptor density and adenylate cyclase that occur postmortem indicate the importance of prompt processing of tissues. The striking similarity in response of beta-adrenergic receptor agonist and antagonist binding and adenylate cyclase activity in ischemic and postmortem tissue raises the speculation that similar mechanisms may operate under both conditions.

scholarly journals Adenovirus type 12 transformation involves loss of beta-adrenergic receptors and isoproterenol responsiveness.

1982 ◽  
Vol 2 (7) ◽  
pp. 805-814
Author(s):  
N Ledinko ◽  
J Schaeufele ◽  
C Chen
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Adenovirus Type ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Transformed Cell ◽  
Transformed Cell Lines

The responsiveness of a growth-regulated rat 3Y1 cell line and five clones of 3Y1 cells transformed by the highly oncogenic human adenovirus type 12 to the catecholamine hormone (-)-isoproterenol was studied. The untransformed cells contained beta-adrenergic receptors characterized by specific binding of the beta-adrenergic receptor antagonist (-)-[3H]dihydroalprenolol, a 9- to 12-fold increase in cyclic AMP production in intact cells after incubation with 10 microM (-)-isoproterenol, and significantly increased adenylate cyclase (ATP pyrophosphatelyase [cyclizing], EC 4.6.1.1) activity in the presence of the hormone. In contrast, (-)-isoproterenol (10 to 100 microM) had no apparent effect on cyclic AMP production or the basal adenylate cyclase activity in the transformed cell lines. Binding studies revealed that untransformed cells contained approximately 19,400 beta-adrenergic receptor sites per cell. Three transformed cell clones tested showed a three- to fourfold loss of beta-adrenergic receptors.

Adenovirus type 12 transformation involves loss of beta-adrenergic receptors and isoproterenol responsiveness

1982 ◽  
Vol 2 (7) ◽  
pp. 805-814
Author(s):  
N Ledinko ◽  
J Schaeufele ◽  
C Chen
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Adenovirus Type ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Transformed Cell ◽  
Transformed Cell Lines

The responsiveness of a growth-regulated rat 3Y1 cell line and five clones of 3Y1 cells transformed by the highly oncogenic human adenovirus type 12 to the catecholamine hormone (-)-isoproterenol was studied. The untransformed cells contained beta-adrenergic receptors characterized by specific binding of the beta-adrenergic receptor antagonist (-)-[3H]dihydroalprenolol, a 9- to 12-fold increase in cyclic AMP production in intact cells after incubation with 10 microM (-)-isoproterenol, and significantly increased adenylate cyclase (ATP pyrophosphatelyase [cyclizing], EC 4.6.1.1) activity in the presence of the hormone. In contrast, (-)-isoproterenol (10 to 100 microM) had no apparent effect on cyclic AMP production or the basal adenylate cyclase activity in the transformed cell lines. Binding studies revealed that untransformed cells contained approximately 19,400 beta-adrenergic receptor sites per cell. Three transformed cell clones tested showed a three- to fourfold loss of beta-adrenergic receptors.

Alpha- and beta-adrenergic receptors in proximal tubules of rat kidney

1987 ◽  
Vol 253 (5) ◽  
pp. F848-F856 ◽  
Author(s):  
P. R. Sundaresan ◽  
T. L. Fortin ◽  
S. L. Kelvie
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Beta Adrenergic Receptors ◽  
Binding Studies ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Proximal Tubular

Proximal tubules were isolated from the rat kidney by collagenase digestion of the cortical tissue followed by Percoll gradient centrifugation. Microscopic and hormone-stimulated adenylate cyclase activity studies proved the purity of the preparation. [3H]Prazosin, [3H]rauwolscine, and [125I]iodocyanopindolol were used to identify and quantitate respectively the alpha 1-, alpha 2- and beta-adrenergic receptors. Proximal tubular (F4) particulate fraction was compared against other cortical nephron segment (F1, F2) fractions and the total collagenase-digested cortex particulate suspension (Ft). Proximal tubules were enriched in alpha 1- and alpha 2-adrenergic receptors compared with Ft (alpha 1-receptor, 100.4 +/- 4.5 vs. 87.4 +/- 4.9; alpha 2-receptor, 250 +/- 16.2 vs. 185.1 +/- 12 fmol/mg protein). The fractions enriched in glomeruli and distal tubular segments (F1, F2) had relatively low concentrations of alpha 1- and alpha 2-adrenergic receptors. In contrast, beta-adrenergic receptor concentration in the proximal tubules was approximately 25% of that in the Ft fraction and approximately 10% of that in the F1 fraction. Isoproterenol-stimulated adenylate cyclase activities in the different fractions corroborated well with the pattern suggested by the [125I]iodocyanopindolol binding studies. Our results suggest that whole-cortex preparation radioligand binding studies may reflect proximal tubular alpha 1- and alpha 2-adrenergic receptor changes quite well. They may, however, miss or give erroneous impressions about beta-adrenergic receptor changes occurring in different cortical nephron segments.

scholarly journals The turkey erythrocyte β-adrenergic receptor couples to both adenylate cyclase and phospholipase C via distinct G-protein α subunits

1994 ◽  
Vol 304 (2) ◽  
pp. 359-364 ◽  
Author(s):  
S R James ◽  
C Vaziri ◽  
T R Walker ◽  
G Milligan ◽  
C P Downes
Keyword(s):  
Adenylate Cyclase ◽  
Phospholipase C ◽  
G Protein ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Inositol Phosphates ◽  
Adenosine Monophosphate ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic

By contrast with mammalian beta-adrenergic receptors, the avian isoform elicits two distinct effector responses, activation of adenylate cyclase and polyphosphoinositide-specific phospholipase C (PLC) leading to the accumulation of both cyclic adenosine monophosphate (cyclic AMP) and inositol phosphates. We have investigated the mechanisms of beta-adrenergic receptor signalling in turkey erythrocytes. Stimulation of adenylate cyclase by the beta-adrenergic-receptor agonist isoprenaline exhibits a 30-fold lower EC50 than that for PLC activation, which may indicate a marked receptor reserve for the former effector. Similar Ki values were obtained for the inhibition of both responses by four beta-adrenergic antagonists, arguing that a single receptor population is responsible for both effects. Antibodies raised against G-protein peptide sequences were used to show that the identity of the G-protein mediating the PLC response was an avian homologue of G11, the level of expression of which was very similar to that of the stimulatory G-protein of adenylate cyclase, Gs. Thus a single population of beta-adrenergic receptors apparently interacts with distinct G-proteins to activate different effectors. The stoichiometries of the receptor-G-protein-effector interactions are therefore similar for both second-messenger responses and the data are discussed in terms of the different efficacies observed for each response.

Hepatic sexual dimorphism: ontogeny and influence of adult gonadectomy

1989 ◽  
Vol 256 (3) ◽  
pp. E392-E400
Author(s):  
R. K. Studer ◽  
L. Ganas
Keyword(s):  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Female Rats ◽  
Adenylate Cyclase System ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Intact Cells ◽  
Beta Adrenergic ◽  
Receptor Concentration ◽  
Males And Females

The ontogeny of alpha 1- and beta-adrenergic receptors and their relative stimulation of phosphorylase alpha activity in hepatic tissue from male and female rats were compared. A decrease in beta-adrenergic receptor concentration and 4-(t-butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazol-2-one HCl affinity for these sites was found in males and females, when data from membranes of 20- to 22-day animals was compared with that from neonates. No subsequent decline in receptor concentration was noted in the female; however, the beta-mediated phosphorylase activation was further diminished by 49-56 days, suggesting maturational changes beyond the receptor-adenylate cyclase system. Although high-affinity beta-adrenergic receptors were documented in membranes from pubertal males, they were not identified on the intact cells, and activation of phosphorylase alpha via the beta-pathway was minimal. This suggests the majority of the beta-receptors are sequestered in cellular sites not accessible to the hydrophilic ligand or epinephrine in the sexually mature male. Ontogeny of the alpha 1-adrenergic receptors was similar in males and females. Gonadectomy of mature males and females did not eliminate the sexual differences in adrenergic response. However, the ovariectomized females developed an enhanced basal and alpha-adrenergic stimulated phosphorylase activity. The rise in cytosolic free calcium in response to epinephrine was increased in the ovariectomized females to values seen in the intact male, whereas the response in the castrate male was depressed. The results suggest the dimorphism in alpha 1- and beta-adrenergic receptor function is determined by factors other than the ambient concentration of sex steroids in the adult.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of age and hypoxia on beta-adrenergic receptors in rat heart

1991 ◽  
Vol 71 (6) ◽  
pp. 2094-2098 ◽  
Author(s):  
S. L. Mader ◽  
C. L. Downing ◽  
E. Van Lunteren
Keyword(s):  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Left Ventricular ◽  
Hypoxic Exposure ◽  
Receptor Density ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Young Rats ◽  
Age Related

Previous reports suggest that hypoxia downregulates cardiac beta-adrenergic receptors from young rats. Because aging alters response to stress, we hypothesized an age-related alteration in the response to hypoxia. Male Fischer-344 rats, aged 3 and 20 mo, were divided into control and hypoxic groups. The hypoxic rats were exposed to hypobaric hypoxia (0.5 atm) for 3 wk. After hypoxic exposure, body weight decreased, hematocrit increased, right ventricular weight increased, and left ventricular weight decreased in all animals. beta-Adrenergic receptor density declined after hypoxic exposure in the young but not in the older animals, a change that was confined to the left ventricle. beta-Adrenergic receptor density in the right ventricle was significantly lower in the older animals than in the young animals. Plasma catecholamines (norepinephrine, epinephrine) drawn after the animals were killed (stress levels) decreased in young rats and increased in old rats after the exposure to hypoxia. Hypoxia is a useful physiological stress that elucidates age-related changes in cardiac beta-adrenergic receptor and catecholamine regulation that have not previously been described.

Effects of hypoxia on density of beta-adrenergic receptors

1981 ◽  
Vol 50 (2) ◽  
pp. 363-366 ◽  
Author(s):  
N. F. Voelkel ◽  
L. Hegstrand ◽  
J. T. Reeves ◽  
I. F. McMurty ◽  
P. B. Molinoff
Keyword(s):  
High Altitude ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Low Dose ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Altitude Exposure

Exposure to chronic hypoxia results in a lower resting heart rate and a blunted cardiovascular responsiveness to beta-adrenergic receptor stimulation. Possible effects of acclimatization to high altitude on the binding of [125I]iodohydroxybenzylpindolol to beta-adrenergic receptors on membranes of right and left ventricles of rat heart were determined. Chronic high-altitude exposure led to a decrease in the density of beta-adrenergic receptors in nonhypertrophied left ventricles as well as in hypertrophied right ventricles. The affinity of the receptor for the radioligand was not changed by the exposure to high altitude, suggesting that the properties of the receptor were not affected. Basal and isoproterenol-stimulated adenylate cyclase activities were decreased in membranes prepared from hearts and pulmonary arteries of rats acclimatized to high altitude. The loss of cardiac beta-adrenergic receptors in rats adapted to high altitude was prevented by the chronic coadministration of a low dose of DL-propranolol. The results suggest that changes in beta-adrenergic receptor density may partially explain the hemodynamic adaptation that occurs with chronic hypoxia. These decreases may be due to a loss of functional beta-adrenergic receptors caused by chronically elevated concentrations of circulating neurally released catecholamines.

beta-Adrenergic receptors in the developing rabbit lung

1981 ◽  
Vol 240 (4) ◽  
pp. E351-E357 ◽  
Author(s):  
J. A. Whitsett ◽  
M. A. Manton ◽  
C. Darovec-Beckerman ◽  
K. G. Adams ◽  
J. J. Moore
Keyword(s):  
Adenylate Cyclase ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Receptor Subtypes ◽  
Beta Adrenergic Receptors ◽  
Rabbit Lung ◽  
Beta Adrenergic ◽  
Beta 2

beta-Adrenergic receptors and catecholamine-sensitive adenylate cyclase were identified and partially characterized in membrane fractions of rabbit lungs from day 25 of gestation to adulthood with the beta-adrenergic antagonists (--)-[3H]dihydroalprenolol [(--)-[3H]DHA] and (--)-[125I]iodohydroxybenzylpindolol [(--)-[125I]HYP]. beta-Adrenergic receptor number (Bmax) increased 11.5-fold during this time period, increasing progressively during the latter days of gestation and the early neonatal period, from 37 +/- 10 fmol/mg protein at 25 days gestation to 425 +/- 51 fmol/mg in the adult rabbit lung (mean +/- SD). Receptor affinity for (--)-[3H]DHA (KD = 1.8 nM) or (--)-[125I]HYP (KD - 0.104 nM) and the proportion of beta 1- and beta 2-adrenergic receptor subtypes (60% beta 1 and 40% beta 2) did not change with advancing age. Basal adenylate cyclase activity in lung homogenates decreased significantly with increasing age, whereas the activity in the presence of catecholamine or NaF remained nearly constant. Catecholamines stimulated adenylate cyclase activity at all ages studied supporting a role of the maturation of beta-adrenergic receptors in the regulation of pulmonary function.

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