The effect of glucagon and prostaglandin E1 on cyclic AMP levels in liver of heat exposed hamsters

1980 ◽  
Vol 93 (4) ◽  
pp. 475-478 ◽  
Author(s):  
Miriam Aharon ◽  
Yosef Graziani ◽  
Reuben Chayoth
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Prostaglandin E1 ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Prostaglandin E ◽  
Liver Slices ◽  
Presence And Absence ◽  
The Difference

Abstract. Cyclic AMP levels in liver slices of hamsters exposed to 35°C for 21 days and controls maintained at 22°C was found to be similar in basal conditions. Glucagon (10 μg/ml) caused 3.5 times elevation of cyclic AMP levels in control hamsters and 9 times elevation in 35°C exposed hamsters, thus a difference of 150% of the nucleotide concentration was found between the two experimental groups. When 10−2m theophylline was added, the cyclic AMP levels were 80% higher in 35°C exposed hamsters both in the presence and absence of 10 μg/ml glucagon. The difference between controls and heat exposed animals was found to be the same when various concentrations of both glucagon or prostaglandin E1 were added to the liver slices. Adenylate cyclase activity was similar in both experimental groups, while low Km phosphodiesterase was significantly less active in the liver of 35°C exposed animals when compared to the controls.

scholarly journals Stimulation of hormone-responsive adenylate cyclase activity by a factor present in the cell cytosol

1980 ◽  
Vol 188 (2) ◽  
pp. 393-400 ◽  
Author(s):  
S MacNeil ◽  
A Crawford ◽  
H Amirrasooli ◽  
S Johnson ◽  
A Pollock ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Adenylate Cyclase ◽  
Prostaglandin E1 ◽  
Enzyme Activation ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Prostaglandin E ◽  
Human Articular Cartilage ◽  
Cell Cytosol ◽  
Stimulation Of

1. Homogenates of whole tissues were shown to contain both intracellular and extracellular factors that affected particulate adenylate cyclase activity in vitro. Factors present in the extracellular fluids produced an inhibition of basal, hormone- and fluoride-stimulated enzyme activity but factors present in the cell cytosol increased hormone-stimulated activity with relatively little effect on basal or fluoride-stimulated enzyme activity. 2. The existence of this cytosol factor or factors was investigated using freshly isolated human platelets, freshly isolated rat hepatocytes, and cultured cells derived from rat osteogenic sarcoma, rat calvaria, mouse melanoma, pig aortic endothelium, human articular cartilage chondrocytes and human bronchial carcinoma (BEN) cells. 3. The stimulation of the hormone response by the cytosol factor ranged from 60 to 890% depending on the tissue of origin of the adenylate cyclase. 4. In each case the behaviour of the factor was similar to the action of GTP on that particular adenylate cyclase preparation. 5. No evidence of tissue or species specificity was found, as cytosols stimulated adenylate cyclase from their own and unrelated tissues to the same degree. 6. In the human platelet, the inclusion of the cytosol in the assay of adenylate cyclase increased the rate of enzyme activity in response to stimulation by prostaglandin E1 without affecting the amount of prostaglandin E1 required for half-maximal stimulation or the characteristics of enzyme activation by prostaglandin E.

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).

scholarly journals Prostaglandin-Endoperoxides and Cyclic 3′-5′-AMP in Platelets of Patients with Uremia

1977 ◽  
Author(s):  
F. R. Matthias ◽  
W. Palinski
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Adenylate Cyclase ◽  
Prostaglandin E1 ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Bleeding Tendency ◽  
Prostaglandin Endoperoxide ◽  
Uremic Patients

In platelets of normal donors and of patients with chronic renal failure the following determinations were performed: 1. prostaglandin-endoperoxide-formation after N-ethylmaleimide stimulation measured as malondialdehyde; 2. the c-AMP level according to the Gilman-method; 3. the adenylate-cyclase activity in response to prostaglandin E1; 4. aggregation in response to collagen.In comparison to’normal donores the prostaglandin-endoperoxide production was reduced in uremic patients. Plasma of uremics depresses the endoperoxide formation of normal platelets. The basal c-AMP level of platelets of’ patients with renal failure was not significantly changed, whereas the plasma c-AMP level was increased; the activation of the platelets adenylate-cyclase was impaired. The adenylate-cyclase activity of platelets from normal donors was reduced by uremic plasma.. The results are of interest as to the explanation of the bleeding tendency of uremic patients.

Fluctuations of adenylate cyclase activity during anterior regeneration in Owenia fusiformis (Polychaete Annelid)

Development ◽  
1978 ◽  
Vol 48 (1) ◽  
pp. 73-78
Author(s):  
Josiane Coulon ◽  
Monique Marilley
Keyword(s):  
Cell Cycle ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Biochemical Assays ◽  
Strong Stimulation ◽  
Periodic Fluctuations ◽  
Early Phases ◽  
Anterior Regeneration

Biochemical assays of adenylate cyclase activity were performed during the early phases of regeneration in Owenia fusiformis (Polychaete Annelid). The results indicate the existence of a strong stimulation in an early phase following trauma. This stimulation is then followed by periodic fluctuations exhibiting a diurnal rhythm correlated with the cell cycle. Adenylate cyclase activity is also shown to be neurotransmitter-dependent. In this paper it is proposed that neurotransmitters might participate in the regulation of cyclic AMP formation, by means of adenylate cyclase acting on target blastema cells, undergoing the cell cycle.

scholarly journals Forskolin refractoriness. Exposure to the diterpene alters guanine nucleotide-dependent adenylate cyclase and calcium-uptake activity of cells cultured from the rat aorta

1987 ◽  
Vol 241 (2) ◽  
pp. 463-467 ◽  
Author(s):  
J F Krall ◽  
N Jamgotchian
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cultured Cells ◽  
Rat Aorta ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Morphological Properties ◽  
Guanine Nucleotide ◽  
Intact Cells ◽  
Uptake Activity

Cells with the morphological properties of endothelial cells were cultured from the rat aorta. The cultured cells accumulated 45Ca2+ from the medium in a manner which was stimulated by forskolin and by 8-bromo-cyclic AMP. Pretreating the cultures for 20 h with forskolin diminished forskolin-dependent Ca2+-uptake activity. Adenylate cyclase activity of cultured cell homogenates was stimulated by guanosine 5′-[beta, gamma-imido]triphosphate (p[NH]ppG) and forskolin, and by isoprenaline in the presence, but not in the absence, of guanine nucleotide. p[NH]ppG increased forskolin sensitivity and caused a leftward shift in the forskolin dose-response curve. Pretreating the cultured cells with forskolin for 20 h, conditions that decreased forskolin-dependent Ca2+ uptake, increased basal and guanine nucleotide-dependent adenylate cyclase activity, but not forskolin-dependent activity determined in the absence of p[NH]ppG. Forskolin pretreatment diminished p[NH]ppG's capacity to increase forskolin sensitivity, but did not have a significant effect on either the sensitivity of adenylate cyclase to p[NH]ppG or its responsiveness to isoprenaline. These results suggest that the Ca2+-uptake mechanism is cyclic AMP-dependent and that guanine nucleotides mediated forskolin-dependent cyclic AMP production by the intact cells. In addition, there may be different guanine nucleotide requirements for hormone-receptor coupling and forskolin activation.

scholarly journals Bradykinin-dependent activation of adenylate cyclase activity and cyclic AMP accumulation in tracheal smooth muscle occurs via protein kinase C-dependent and -independent pathways

1994 ◽  
Vol 297 (1) ◽  
pp. 233-239 ◽  
Author(s):  
P A Stevens ◽  
S Pyne ◽  
M Grady ◽  
N J Pyne
Keyword(s):  
Smooth Muscle ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cholera Toxin ◽  
Phospholipase D ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Tracheal Smooth Muscle ◽  
Constitutive Activation ◽  
Cyclic Amp Accumulation

Treatment of cultured tracheal smooth-muscle cells (TSM) with phorbol 12-myristate 13-acetate (PMA) (100 nM) or bradykinin (100 nM) elicited enhanced basal and guanosine 5′-[beta gamma-imido]-triphosphate-stimulated adenylate cyclase activities in subsequently isolated membranes. Combined stimulation of cells was non-additive, indicating that both agents activate adenylate cyclase via similar routes. Both PMA (100 nM) and bradykinin (100 nM) allowed the alpha subunit of Gs to act as a more favourable substrate for its cholera-toxin-catalysed ADP-ribosylation in vitro. PMA was without effect on intracellular cyclic AMP in control cells. However, constitutive activation of Gs by treatment in vivo with cholera toxin (0.5 ng/ml, 18 h) sensitized the cells to PMA stimulation, resulting in a concentration-dependent increase in intracellular cyclic AMP accumulation (EC50 = 7.3 +/- 2.5 nM, n = 5). Bradykinin also elicited a concentration-dependent increase in intracellular cyclic AMP (EC50 = 63.3 +/- 14.5 nM, n = 3). Constitutive activation of Gs resulted in an increased maximal response (10-fold) and potency (EC50 = 6.17 +/- 1.6 nM, n = 3) to bradykinin. This response was not affected by the B2-receptor antagonist, NPC567 [which selectively blocks bradykinin-stimulated phospholipase C (PLC), with minor activity against phospholipase D (PLD) activity]. Des-Arg9-bradykinin (a B1-receptor agonist) was without activity. These results suggest that the receptor sub-type capable of activating PLD may also be stimulatory for cyclic AMP accumulation. Furthermore, pre-treatment of the cells with butan-l-ol (0.3%, v/v), which traps phosphatidate derived from PLD reactions, blocked the bradykinin-stimulated increase in intracellular cyclic AMP. These studies suggest that there may be a causal link between PLD-derived phosphatidate and the positive modulation of adenylate cyclase activity. In support of this, the concentration-dependence for bradykinin-stimulated adenylate cyclase activity was identical with that of bradykinin-stimulated phospholipase D activity (EC50 = 5 nM). Bradykinin, but not PMA, was also capable of eliciting the inhibition of cyclic AMP phosphodiesterase activity in TSM cells (EC50 > 100 nM) via an unidentified mechanism. These studies indicate that cross-regulation between the cyclic AMP pathway and phospholipid-derived second messengers in TSM cells does not occur as a consequence of PLC-catalysed PtdIns(4,5)P2 hydrolysis, but may involve, in part, PLD-catalysed phosphatidylcholine hydrolysis.

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