scholarly journals Breed-related differences in age-dependent down-regulation of the β1-adrenoceptor and adenylate cyclase activity in atrial and ventricular myocardium of Cröllwitzer (“wild-type”) turkeys

2018 ◽  
Vol 97 (3) ◽  
pp. 1041-1049
Author(s):  
Sandra Hoffmann ◽  
Julia Böhme ◽  
Christian Kube ◽  
Michael Pees ◽  
Jörg Haufe ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Ventricular Myocardium ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Wild Type ◽  
Down Regulation ◽  
Age Dependent

Age-dependent mechanical and biochemical responses to glucagon

1976 ◽  
Vol 230 (6) ◽  
pp. 1590-1593 ◽  
Author(s):  
G Ahumada ◽  
BE Sobel ◽  
WF Friedman
Keyword(s):  
Adenylate Cyclase ◽  
Ventricular Myocardium ◽  
Fetal Tissue ◽  
Particulate Fraction ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Glucagon Receptor ◽  
Tension Development ◽  
Receptor Sites ◽  
Age Dependent

The age-dependent relationships between glucagon-induced alterations in myocardial mechanics and adenylate cyclase activity in fetal and newborn lambs and adult sheep were evaluated. Glucagon substantially augmented the force of contraction of ventricular myocardium isolated from the adult but not from the fetus or newborn. Similarly, substantial increases in the spontaneous frequency of contraction and tension were observed in adult atrial strips, but not in the fetus or newborn. Comparable activities of phosphodiesterase were observed in extracts from fetal and adult myocardium and were unaltered by the addition of glucagon. Adenylate cyclase activity in adult myocardial homogenate and particulate fractions was comparable to that of fetal tissue. Glucagon stimulation of the particulate fraction produced no change in fetal adenylate cyclase activity whereas a 43% increase in activity was observed in preparations from adult tissue. Sodium fluoride and epinephrine augmented adenylate cyclase activity in both fetal and adult myocardium. Thus, glucagon produced age-dependent, parallel changes in heart rate, active tension development, and particulate fraction adenylate cyclase activity, suggesting that these chronotropic and inotropic responses are indeed mediated by adenylate cyclase and that lack of response in the fetus reflects the absence of mature glucagon receptor sites.

scholarly journals Differential down-regulation of D1-stimulated adenylate cyclase activity in rat forebrain after in vivo amphetamine treatments

1986 ◽  
Vol 6 (8) ◽  
pp. 2245-2251 ◽  
Author(s):  
JM Roberts-Lewis ◽  
PH Roseboom ◽  
LM Iwaniec ◽  
ME Gnegy
Keyword(s):  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Down Regulation ◽  
Rat Forebrain

Down-regulation in vivo of PGE receptors and adenylate cyclase stimulation

1980 ◽  
Vol 239 (1) ◽  
pp. E75-E80
Author(s):  
R. P. Robertson ◽  
K. R. Westcott ◽  
D. R. Storm ◽  
M. G. Rice
Keyword(s):  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Binding Affinity ◽  
Membrane Receptors ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Down Regulation ◽  
Liver Plasma Membrane ◽  
Plasma Membrane Receptors

Down-regulation in vivo of liver plasma membrane receptors for prostaglandin E (PGE) was investigated in Sprague-Dawley rats using the 16,16-dimethyl analogue of PGE2, This analogue was used for subcutaneous injections because it escapes the rapid pulmonic degradation characteristic of PGE and was recognized well by liver plasma membrane receptors. Following treatment with the analogue, the concentration of PGE receptors was significantly decreased (-37%, P less than 0.001), but the binding affinity was not altered. There was no evidence for carry-through of the analogue into the isolated plasma membrane preparation. It was also demonstrated that GTP decreased the binding affinity between PGE and its receptor. Down-regulation of receptor concentration was associated with a significant decrease (P less than 0.001) in PGE1-stimulated plasma membrane adenylate cyclase activity. These data provide the novel demonstration that rat liver plasma membrane receptor for PGE can be down-regulated in vivo and that this causes a corresponding decrease in PGE-induced plasma membrane adenylate cyclase activity.

scholarly journals Regulation of basal adenylate cyclase activity in neuroblastoma × glioma hybrid, NG108-15, cells transfected to express the human β 2 adrenoceptor: evidence for empty receptor stimulation of the adenylate cyclase cascade

1994 ◽  
Vol 303 (3) ◽  
pp. 803-808 ◽  
Author(s):  
E J Adie ◽  
G Milligan
Keyword(s):  
Membrane Protein ◽  
Adenylate Cyclase ◽  
Receptor Activation ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Wild Type ◽  
Catalytic Unit ◽  
Beta 2 ◽  
Signalling Cascade ◽  
Stimulation Of

Clones of neuroblastoma x glioma hybrid, NH108-15, cells expressing differing levels of the human beta 2 adrenoceptor were isolated. Two clones were examined in detail, beta N22 which expressed some 4000 fmol/mg of membrane protein and clone beta N17 which expressed approx. 300 fmol/mg of membrane protein of the receptor. In beta N22 cells ‘basal’ adenylate cyclase activity measured in the presence of Mg2+ was significantly greater than that in wild-type NG108-15 or beta N17 cells. Both isoprenaline and iloprost were able to stimulate adenylate cyclase activity in each of beta N22 and beta N17 membranes. However, the EC50 for isoprenaline stimulation of adenylate cyclase in membranes of beta N22 cells (6 nM) was significantly lower than that in membranes of beta N17 cells (80 nM), whereas the EC50 for iloprost stimulation of adenylate cyclase (approx. 25 nM) was the same in the two clones and in parental NG108-15 cells. The high basal adenylate cyclase activity of beta N22 cell membranes was not a reflection of higher levels of expression of the adenylate cyclase catalytic unit, as adenylate cyclase activity measured in the presence of Mn2+ was equivalent in membranes of each of wild-type NG108-15 cells and clones beta N22 and beta N17. Basal adenylate cyclase activity measured in the presence of Mg2+ in clone beta N22 was significantly reduced, however, by the beta-receptor antagonist propranolol, whereas this agent was without effect on basal adenylate cyclase activity in membranes of wild-type NG108-15 cells. These data indicate that the elevated basal adenylate cyclase cascade in NG108-15 cells expressing high levels of the beta 2 adrenoceptor represents empty receptor activation of the signalling cascade.

Cytochemical Evidence for Presynatic β-Adrenergic Regulation of Secretion in the Developing Rat Submandibular Gland

1977 ◽  
Vol 35 ◽  
pp. 430-431
Author(s):  
L.S. Cutler
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Submandibular Gland ◽  
Neonatal Rat ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Parotid Glands ◽  
Adrenergic Agonist ◽  
Rat Submandibular Gland

Many studies previously have shown that the B-adrenergic agonist isoproterenol and the a-adrenergic agonist norepinephrine will stimulate secretion by the adult rat submandibular (SMG) and parotid glands. Recent data from several laboratories indicates that adrenergic agonists bind to specific receptors on the secretory cell surface and stimulate membrane associated adenylate cyclase activity which generates cyclic AMP. The production of cyclic AMP apparently initiates a cascade of events which culminates in exocytosis. During recent studies in our laboratory it was observed that the adenylate cyclase activity in plasma membrane fractions derived from the prenatal and early neonatal rat submandibular gland was retractile to stimulation by isoproterenol but was stimulated by norepinephrine. In addition, in vitro secretion studies indicated that these prenatal and neonatal glands would not secrete peroxidase in response to isoproterenol but would secrete in response to norepinephrine. In contrast to these in vitro observations, it has been shown that the injection of isoproterenol into the living newborn rat results in secretion of peroxidase by the SMG (1).

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