scholarly journals Multiple receptors linked to inhibition of adenylate cyclase accelerate Na+/H+ exchange in neuroblastoma x glioma cells via a mechanism other than decreased cAMP accumulation.

1987 ◽  
Vol 262 (36) ◽  
pp. 17504-17509 ◽  
Author(s):  
L L Isom ◽  
E J Cragoe ◽  
L E Limbird
Keyword(s):  
Adenylate Cyclase ◽  
Glioma Cells ◽  
Camp Accumulation ◽  
Multiple Receptors

Ticlopidine and Clopidogrel (SR 25990C) Selectively Neutralize ADP Inhibition of PGE1-Activated Platelet Adenylate Cyclase in Rats and Rabbits

1991 ◽  
Vol 65 (02) ◽  
pp. 186-190 ◽  
Author(s):  
G Defreyn ◽  
C Gachet ◽  
P Savi ◽  
F Driot ◽  
J P Cazenave ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Adenylate Cyclase ◽  
Direct Effect ◽  
Cyclic Nucleotide ◽  
Camp Accumulation ◽  
Rabbit Platelets ◽  
Camp Levels ◽  
Kinetics Of ◽  
Camp Elevation ◽  
Rat Platelets

SummaryTiclopidine and its potent analogue, clopidogrel, are powerful inhibitors of ADP-induced platelet aggregation. In order to improve the understanding of this ADP-selectivity, we studied the effect of these compounds on PGE1-stimulated adenylate cyclase and on the inhibition of this enzyme by ADP, epinephrine and thrombin. Neither drug changed the basal cAMP levels nor the kinetics of cAMP accumulation upon PGEj-stimulation in rat or rabbit platelets, which excludes any direct effect on adenylate cyclase or on cyclic nucleotide phosphodiesterase. However, the drop in cAMP levels observed after addition of ADP to PGEr stimulated control platelets was inhibited in platelets from treated animals. In contrast, the drop in cAMP levels produced by epinephrine was not prevented by either drug in rabbit platelets. In rat platelets, thrombin inhibited the PGEX-induced cAMP elevation but this effect seems to be entirely mediated by the released ADP. Under these conditions, it was not surprising to find that clopidogrel also potently inhibited that effect of thrombin on platelet adenylate cyclase. In conclusion, ticlopidine and clopidogrel selectively neutralize the ADP inhibition of PGEr activated platelet adenylate cyclase in rats and rabbits.

scholarly journals Transfected Go1 alpha inhibits the calcium dependence of beta-adrenergic stimulated cAMP accumulation in C6 glioma cells.

1993 ◽  
Vol 268 (12) ◽  
pp. 8980-8989
Author(s):  
N. Charpentier ◽  
L. Prézeau ◽  
J. Carrette ◽  
R. Bertorelli ◽  
G. Le Cam ◽  
...  
Keyword(s):  
Glioma Cells ◽  
C6 Glioma ◽  
C6 Glioma Cells ◽  
Camp Accumulation ◽  
Beta Adrenergic ◽  
Calcium Dependence

Turn on and turn off reactions of β-adrenergic-sensitive adenylate cyclase in control and desensitized C6 glioma cells

FEBS Letters ◽  
1982 ◽  
Vol 141 (2) ◽  
pp. 245-250
Author(s):  
Vincent Homburger ◽  
Marguerite Lucas ◽  
Joël Bockaert
Keyword(s):  
Adenylate Cyclase ◽  
Glioma Cells ◽  
C6 Glioma ◽  
C6 Glioma Cells ◽  
Turn On

Changes in expression of a functional Gi protein in cultured rat heart cells

1988 ◽  
Vol 255 (1) ◽  
pp. C51-C59 ◽  
Author(s):  
I. S. Allen ◽  
S. T. Gaa ◽  
T. B. Rogers
Keyword(s):  
Adenylate Cyclase ◽  
Pertussis Toxin ◽  
Rat Heart ◽  
Neonatal Rat ◽  
Heart Cells ◽  
Dependent Manner ◽  
Camp Accumulation ◽  
Ang Ii ◽  
Rat Heart Myocytes ◽  
Neonatal Rat Heart

The muscarinic cholinergic agonist, carbachol, and pertussis toxin were used to examine the functional status of the guanine nucleotide-binding protein that inhibits adenylate cyclase (Gi) in cultured neonatal rat heart myocytes. The isoproterenol stimulation of adenylate cyclase activity in myocyte membranes and adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in intact cells (4 days in culture) were insensitive to carbachol (0.1 mM). However, in cells cultured for 11 days, carbachol (0.1 mM) inhibited isoproterenol-stimulated cAMP accumulation by 30%. Angiotensin II (ANG II) was also found to inhibit isoproterenol-stimulated cAMP accumulation in day 11 cells in a dose-dependent manner. Pertussis toxin treatment reversed the inhibitory effects of both ANG II and carbachol, suggesting a role for Gi in the process. Carbachol binding to membranes from day 4 cells was relatively insensitive to guanine nucleotides when compared with binding to membranes from day 11 or adult cells. Furthermore, pertussis toxin-mediated 32P incorporation into a 39- to 41-kDa substrate in day 11 membranes was increased 3.2-fold over that measured in day 4 membranes. These findings support the view that, although Gi is expressed, it is nonfunctional in 4-day-old cultured neonatal rat heart myocytes and acquisition of functional Gi is dependent on culture conditions. Furthermore, the ANG II receptor can couple to Gi in heart.

Histamine responsiveness of isolated gastric glands

1980 ◽  
Vol 238 (4) ◽  
pp. G312-G320 ◽  
Author(s):  
C. S. Chew ◽  
S. J. Hersey ◽  
G. Sachs ◽  
T. Berglindh
Keyword(s):  
Adenylate Cyclase ◽  
Histamine Receptor ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Uptake System ◽  
Camp Accumulation ◽  
Response Curves ◽  
Gastric Glands ◽  
Pharmacological Characterization ◽  
Histamine Uptake

Gastric glands isolated from rabbit were employed to perform a pharmacological characterization of the histamine receptor associated with physiological and biochemical responses in gastric cells. Five separate response parameters were characterized using histamine analogues and histamine antagonists. The following parameters were studied: respiration, accumulation of the weak base aminopyrine, adenylate cyclase activity, cAMP accumulation, and the uptake of histamine. All parameters were examined for agonist and antagonist potency using dose-response curves, ED50 and pA2 values. Comparison of the ED50-agonist and pA2-cimetidine values showed a remarkable similarity for respiration, aminopyrine accumulation, adenylate cyclase activity, and cAMP accumulation. The agonist potency sequence and pA2 values for H2- vs. H1-receptor antagonists characterized the histamine receptor associated with these four parameters as being of the H2 type. Moreover, the similarity of pharmacological characteristics provides evidence for a similar, if not common, receptor for these responses. The histamine uptake system shows a generally lower affinity for most agonists. Although the general agonist potency sequence is similar to the other parameters, notable exceptions were found for antagonists and the typical H2-agonist, dimaprit. Thus, the uptake system does not appear to be related directly to the activation of secretion and the carrier binding site cannot be simply defined by H1 or H2 properties.

Effect of P1-purinergic agonist on thyrotropin stimulation of H2O2 generation in FRTL-5 and porcine thyroid cells

1994 ◽  
Vol 130 (2) ◽  
pp. 180-186 ◽  
Author(s):  
Ulla Björkman ◽  
Ragnar Ekholm
Keyword(s):  
Adenylate Cyclase ◽  
Primary Culture ◽  
Purinergic Receptor ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Camp Accumulation ◽  
High Concentration ◽  
Thyroid Cells ◽  
H2o2 Generation ◽  
Stimulation Of

Björkman U, Ekholm R. Effect of P1-purinergic agonist on thyrotropin stimulation of H2O2 generation in FRTL-5 and porcine thyroid cells. Eur J Endocrinol 1994;130:180–6. ISSN 0804–4643 Our previous studies have shown that the generation of H2O2 in FRTL-5 thyroid cells is regulated via both the adenylate cyclase/cyclic adenosine monophosphate (cAMP) and Ca2+/phosphatidylinositol pathway: thyrotropin (TSH) stimulates H2O2 generation through both pathways, via the former at a low concentration and via the latter at a high concentration. In porcine thyrocytes in primary culture H2O2 generation is stimulated only via the Ca2+/phosphatidylinositol route. In the present study we explored the effect of a P1-purinergic agonist (phenylisopropyladenosine, PIA) on stimulations induced by TSH and by adenosine triphosphate (ATP), an activator of the Ca2+/phosphatidylinositol cascade via the P2-purinergic receptor. In FRTL- 5 cells, PIA potentiated H2O2 generation stimulated by TSH at 10U/l (but not at 1 U/l), Ca2+ mobilization induced by TSH and Ca2+ mobilization induced by ATP at 1 μmol/l (but not 10 μmol/l). Phenylisopropyladenosine strongly inhibited TSH-induced cAMP accumulation in FRTL-5 cells. In pig thyrocytes, PIA had no effect on H2O2 generation stimulated by TSH or ATP and no effect on ATP-stimulated Ca2+ mobilization. Also, PIA did not inhibit TSH-stimulated cAMP accumulation in pig thyrocytes, and by itselfhad no effecton H2O2 generation or Ca2 + mobilization. Thus, in FRTL-5 cells, but not in porcine thyrocytes, PIA modulates TSH-stimulated H2O2 generation by enhancing the Ca2+/phosphatitylinositol route and inhibiting the adenylate cyclase/cAMP route of the TSH signal. The net result of this modulation apparently depends on the balance between inhibition of the cAMP route and enhancement of the Ca2+ route. This may explain the lack of potentiation observed by 1 U/1 TSH. Ragnar Ekholm, Department of Anatomy, Medicinaregatan 3, S-413 90 Göteborg, Sweden

Pituitary adenylate cyclase-activating peptide stimulates cyclic AMP accumulation in UMR 106 osteoblast-like cells

1996 ◽  
Vol 149 (2) ◽  
pp. 287-295 ◽  
Author(s):  
C S Kovacs ◽  
C L Chik ◽  
B Li ◽  
E Karpinski ◽  
A K Ho
Keyword(s):  
Adenylate Cyclase ◽  
Bone Cells ◽  
Tumor Cell Line ◽  
Camp Accumulation ◽  
Kinase C ◽  
Cyclic Amp Accumulation ◽  
Pituitary Adenylate Cyclase ◽  
And Function ◽  
Umr 106

Abstract Pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) share 68% homology and function as neurotransmitters or neuroendocrine factors. Although VIP immunoreactivity has been detected in bone cells, the presence of PACAP or PACAP receptors in bone has not been determined. In this study, we investigated the role of PACAP and VIP in regulating cAMP accumulation in the UMR 106 osteoblast-like tumor cell line. PACAP 27 (10−9 to 3 × 10−7 m), PACAP 38 (10−9 to 3 × 10−7 m) and VIP (10−8 to 10−6 m) stimulated cAMP accumulation up to eightfold. PACAP 27 was slightly more potent than PACAP 38, and both were tenfold more potent than VIP. Both PACAP- and VIP-stimulated cAMP accumulation were potentiated by 4β-phorbol 12-myristate 13-acetate, an activator of protein kinase C. Two PACAP antagonists, PACAP 6–27 (3 × 10−6 m) and PACAP 6–38 (3 × 10−6 m), blocked PACAP- and VIP-stimulated cAMP accumulation. Two VIP antagonists ([Lys1,Pro2,5,Arg3,4,Tyr6]-VIP, and 4 Cl-d-Phe6,Leu17]-VIP) did not reduce the PACAP-or VIP-stimulated cAMP accumulation. Pretreatment with PACAP 27, PACAP 38 or VIP equally blocked PACAP- and VIP-stimulated cAMP accumulation. These results suggest that PACAP is a more potent stimulator of cAMP accumulation than VIP in UMR 106 cells. PACAP and VIP may share a role in the paracrine or neuroendocrine regulation of bone metabolism. Journal of Endocrinology (1996) 149, 287–295

Sign in / Sign up

Export Citation Format

Share Document