Dibutyryl cyclic AMP increases phosphodiesterase activity in the rat heart

1984 ◽  
Vol 62 (9) ◽  
pp. 1225-1230 ◽  
Author(s):  
Warren K. Palmer ◽  
Sylvia Doukas
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
White Muscle ◽  
Supernatant Fraction ◽  
Red Muscle ◽  
Injection Protocol ◽  
Fast Twitch ◽  
Dose Dependent ◽  
Increased Activity

The influence of increasing the in vivo concentration of cyclic AMP on the activity of cyclic nucleotide phosphodiesterase (PDE) in rat heart was investigated. One, three, and five hourly injections of 5.0 mg dibutyryl (Bt2) cyclic AMP significantly increased the activity of PDE in the supernatant fraction of rat heart using 1.0 μM cyclic AMP as the assay substrate concentration. When 100 μM cyclic AMP was used in the assay reaction, increases in enzymes activity were seen following five and eight nucleotide injections. The nucleotide-induced increase in PDE activity was dose dependent. When the five-injection protocol was used, PDE activity remained elevated for at least 4 h, while activity had returned to control levels within this time when two hourly injections were used. The nucleotide stimulation of PDE activity was blocked by cycloheximide. Five hourly infections of Bt2 cyclic AMP increased PDE activity in the liver and fast-twitch red muscle. A reduction in PDE activity in fast-twitch white muscle was seen following nucleotide injections. These findings are consistent with the hypothesis that prolonged elevations in the intracellular concentration of cyclic AMP cause an elevation in myocardial PDE activity. The increased activity seems to be the result of protein synthesis. These data suggest that cyclic AMP contributes significantly in regulating its own metabolism in the rat heart.

Modulation of the biological activity of thyrotrophin by anti-human thyrotrophin monoclonal antibodies

1990 ◽  
Vol 126 (2) ◽  
pp. 333-340 ◽  
Author(s):  
S. R. Page ◽  
A. H. Taylor ◽  
W. Driscoll ◽  
M. Baines ◽  
R. Thorpe ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Biological Activity ◽  
Monoclonal Antibodies ◽  
Cyclic Amp ◽  
Receptor Activation ◽  
Camp Production ◽  
Dose Dependent ◽  
Bovine Tsh

ABSTRACT The mechanism by which monoclonal antibodies enhance the biological activity of a number of hormones is poorly understood. One such antibody (GC73), which binds to human but not bovine TSH, enhances the bioactivity of human TSH in vivo. We have investigated whether GC73 enhancement of TSH bioactivity involves potentiation of hormone-receptor activation assessed by the cyclic AMP (cAMP) responses of both primary human thyrocyte cultures and a TSH-responsive human thyrocyte cell line (SGHTL-45). GC73 had no effect on basal cAMP production. In contrast to its enhancement of the bioactivity of human TSH in vivo, it markedly inhibited the cAMP response to 1 and 10 mU human TSH/ml in primary thyrocytes. This effect was dose-dependent with neutralization of the bioactivity of TSH occurring at 2 mg GC73/ml. GC73 had no effect on the bioactivity of bovine TSH. In contrast, a second anti-TSH monoclonal antibody (TC12), which binds to both human and bovine TSH, inhibited the bioactivity of both species of TSH. Similar results were obtained using SGHTL-45 cells, although the peak concentrations of cAMP were lower. We conclude that binding of GC73 to human TSH resulted in inhibition rather than enhancement of the in-vitro biological activity of human TSH. We suggest that GC73 enhancement of human TSH bioactivity seen in vivo does not result from a mechanism involving potentiation of receptor activation by human TSH. Journal of Endocrinology (1990) 126, 333–340

In Vivo Assimilation by Cod Muscle and Liver Tissue of Elemental Phosphorus from Polluted Sea Water

1970 ◽  
Vol 27 (6) ◽  
pp. 1131-1139 ◽  
Author(s):  
W. J. Dyer ◽  
D. F. Hiltz ◽  
R. G. Ackman ◽  
J. Hingley ◽  
G. L. Fletcher
Keyword(s):  
Lipid Content ◽  
Liver Tissue ◽  
White Muscle ◽  
Content Distribution ◽  
Sea Water ◽  
Elemental Phosphorus ◽  
Red Muscle ◽  
Seawater Environment ◽  
Exposure Levels

Cod rapidly assimilated elemental phosphorus from a seawater environment into their tissues. In a 16-hr exposure to a concentration of 20–80 ppb (parts per billion), phosphorus was concentrated a thousandfold in the liver (even more at lower exposure levels), from 10 to 25 times in white muscle, and about 50–100 times in red muscle. This distribution is roughly in proportion to lipid content. Distribution of the absorbed phosphorus is uniform throughout the white muscle of the fillet, thus facilitating sampling.

scholarly journals GLYCOGEN SYNTHETASE AND PHOSPHORYLASE IN RED AND WHITE MUSCLE OF RAT AND RHESUS MONKEY

1966 ◽  
Vol 14 (7) ◽  
pp. 549-559 ◽  
Author(s):  
ROSE MARY BOCEK ◽  
CLARISSA H. BEATTY
Keyword(s):  
Rhesus Monkey ◽  
White Muscle ◽  
Muscle Fibers ◽  
Supernatant Fraction ◽  
Glycogen Synthetase ◽  
Red Muscle ◽  
Histochemical Evidence ◽  
Red And White Muscles

Homogenates of red and white muscles from rats and monkeys were assayed for total phosphorylase and phosphorylase a and for the total and independent forms of glycogen synthetase. Total and phosphorylase a activities were higher in the supernatant fraction of homogenates of white as compared with red muscle from both rats and monkeys. Both forms of phosphorylase were higher in white muscle from rats when assayed on whole homogenates. The total and d form of glycogen synthetase activities were higher in red muscle from both species of animals. The ratio of I/total synthetase was 2- to 3-fold higher in muscle from monkeys as compared with that from rats. These results support histochemical evidence that phosphorylase is higher in white muscle fibers and glycogen synthetase is higher in red muscle fibers.

scholarly journals The release of 3′:5′-cyclic monophosphate from the isolated perfused rat heart

1975 ◽  
Vol 152 (2) ◽  
pp. 429-432 ◽  
Author(s):  
John A. O'Brien ◽  
Richard C. Strange
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
Perfused Rat Heart ◽  
Cyclic Monophosphate ◽  
Isolated Perfused Rat Heart ◽  
Rat Hearts ◽  
Basal Release ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Although basal release of cyclic AMP from isolated perfused rat hearts was not measurable, isoprenaline induced substantial release of the nucleotide, suggesting that in vivo the myocardium can contribute to plasma cyclic AMP. Anoxia also increased the amount of cyclic AMP released, but insulin and nicotinate alone or in combination had no effect.

scholarly journals Salmon calcitonin-induced stimulation of 1α,25-dihydroxycholecalciferol synthesis in rats involving a mechanism independent of adenosine 3′:5′-cyclic monophosphate

1979 ◽  
Vol 184 (2) ◽  
pp. 269-275 ◽  
Author(s):  
N Horiuchi ◽  
H Takahashi ◽  
T Matsumoto ◽  
N Takahashi ◽  
E Shimazawa ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Salmon Calcitonin ◽  
Rat Kidney ◽  
Plasma Concentrations ◽  
Maximal Effect ◽  
Balance Study ◽  
System A ◽  
Dose Dependent Increase ◽  
Dose Dependent

The effect of natural salmon calcitonin on accumulation in plasma of 1 alpha,25-dihydroxy-[3H]cholecalciferol from 25-hydroxy[3H]cholecalciferol in vivo was investigated in vitamin D-deficient thyroparathyroidectomized rats into which graded doses of the hormone were continuously infused by use of a balance study system. A dose-dependent increase in plasma concentrations of 1 alpha,25-dihydroxy[3H]cholecalciferol was observed with calcitonin infusion for 6–30h at a rate greater than 20 M.R.C. m-units/h. Infusion of parathyrin or cyclic AMP produced a similar stimulation [Horiuchi, Suda, Takahashi, Shimazawa & Ogata (1977) Endocrinoly 101, 969–974], but the maximal effect of calcitonin was additive to that of either parathyrin or cyclic AMP. Furthermore concurrent infusion of theophylline (0.5 mumol/h) did not potentiate the effect of submaximal doses (3 and 20 M.R.C. m-units/h) of calcitonin. Plasma concentrations of calcium showed a decrease with calcitonin infusion for 30h, but those of Pi remained unchanged. These results strongly suggest that the rat kidney is endowed with a calcitonin-sensitive 1 alpha-hydroxylase system that is separate from the parathyrin/cyclic AMP system and is independent of changes in plasma Pi.

Physiological regulation of the expression of a GLUT4 homolog in fish skeletal muscle

2002 ◽  
Vol 283 (1) ◽  
pp. E44-E49 ◽  
Author(s):  
Encarnación Capilla ◽  
Mònica Dı́az ◽  
Joaquim Gutiérrez ◽  
Josep V. Planas
Keyword(s):  
Skeletal Muscle ◽  
Plasma Levels ◽  
White Muscle ◽  
Glucose Transporter ◽  
Physiological Regulation ◽  
Low Protein ◽  
Red Muscle ◽  
High Sequence Homology ◽  
Trout Muscle

We have recently cloned a glucose transporter from brown trout muscle (btGLUT) with high sequence homology to mammalian GLUT4 that is predominantly expressed in red and white skeletal muscle, the two major sites of glucose uptake in trout. To study the physiological regulation of this putative fish GLUT4, we have investigated the expression of btGLUT in red and white skeletal muscle of trout in which blood insulin levels have been altered experimentally. The expression of btGLUT in red muscle increased significantly when insulin plasma levels were elevated by either insulin or arginine treatment and decreased significantly when insulin plasma levels were reduced either by fasting or by feeding a low-protein, high-carbohydrate diet. In contrast, the expression of btGLUT in white muscle was not affected by changes in the plasma levels of insulin. These results strongly suggest that insulin could be regulating the expression of btGLUT in trout red muscle in vivo and set the ground to test the hypothesis that btGLUT may be considered a GLUT4 homolog in fish.

scholarly journals SGK1 Inhibits Autophagy in Murine Muscle Tissue

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Theresia Zuleger ◽  
Julia Heinzelbecker ◽  
Zsuzsanna Takacs ◽  
Catherine Hunter ◽  
Jakob Voelkl ◽  
...  
Keyword(s):  
Muscle Tissue ◽  
White Muscle ◽  
Autophagic Flux ◽  
Tissue Extracts ◽  
Muscle Tissues ◽  
Red Muscle ◽  
Autophagic Degradation

Background/Aims. As autophagy is linked to several pathological conditions, like cancer and neurodegenerative diseases, it is crucial to understand its regulatory signaling network. In this study, we investigated the role of the serum- and glucocorticoid-induced protein kinase 1 (SGK1) in the control of autophagy. Methods. To measure autophagic activity in vivo, we quantified the abundance of the autophagy conjugates LC3-PE (phosphatidylethanolamine) and ATG12-ATG5 in tissue extracts of SGK1 wild-type (Sgk1+/+) and knockout (Sgk1−/−) mice that were either fed or starved for 24 h prior sacrifice. In vitro, we targeted SGK1 by RNAi using GFP-WIPI1 expressing U-2 OS cells to quantify the numbers of cells displaying newly formed autophagosomes. In parallel, these cells were also assessed with regard to LC3 and ULK1 by quantitative Western blotting. Results. The abundance of both LC3-PE (LC3-II) and ATG12-ATG5 was significantly increased in red muscle tissues of SGK1 knockout mice. This was found in particular in fed conditions, suggesting that SGK1 may keep basal autophagy under control in red muscle in vivo. Under starved conditions, significant differences were observed in SGK1-deficient white muscle tissue and, under fed conditions, also in the liver. In vitro, we found that SGK1 silencing provoked a significant increase of cells displaying WIPI1-positive autophagosomes and autophagosomal LC3 (LC3-II). Moreover, autophagic flux assessments revealed that autophagic degradation significantly increased in the absence of SGK1, strongly suggesting that SGK1 inhibits both autophagosome formation and autophagic degradation in vitro. In addition, more ULK1 protein lacking the inhibitory, TORC1-specific phosphorylation at serine 758 was detected in the absence of SGK1. Conclusions. Combined, our data strongly support the idea that SGK1 inhibits the process of autophagy. Mechanistically, our data suggest that SGK1 should act upstream of ULK1 in regulating autophagy, and we hypothesize that SGK1 contributes to the regulation of ULK1 gene expression.

scholarly journals A reappraisal of the effects of adenosine 3′:5′-cyclic monophosphate on the function and morphology of the rat prostate gland

1973 ◽  
Vol 134 (1) ◽  
pp. 129-142 ◽  
Author(s):  
F. R. Mangan ◽  
A. E. Pegg ◽  
W. I. P. Mainwaring
Keyword(s):  
Cyclic Amp ◽  
Prostate Gland ◽  
Hormonal Treatment ◽  
Supernatant Fraction ◽  
Metabolizing Enzymes ◽  
Biochemical Processes ◽  
Rat Prostate ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Stimulation Of

1. A comparison was made of the binding of 5α-dihydrotestosterone (17β-hydroxy-5α-androstan-3-one) and cyclic AMP in the rat prostate gland. Distinct binding mechanisms exist for these compounds, and cyclic AMP cannot serve as a competitor for the 5α-dihydrotestosterone-binding sites and vice versa. In contrast with the results obtained with 5α-dihydrotestosterone, very small amounts of cyclic AMP are retained in nuclear chromatin and the overall binding of this cyclic nucleotide is not markedly affected by castration. 2. Androgenic stimulation does not lead to major increases in the adenylate cyclase activities associated with any subcellular fraction of the prostate gland. Accordingly, changes in the concentration of cyclic AMP in the prostate gland after hormonal treatment are likely to be small, but these were not measured directly. 3. When administered to whole animals in vivo, small amounts of non-degraded cyclic AMP are found in the prostate gland but sufficient to promote an activation of certain carbohydrate-metabolizing enzymes in the cell supernatant fraction. The stimulatory effects of cyclic AMP were not evident with cytoplasmic enzymes engaged in polyamine synthesis or nuclear RNA polymerases. These latter enzymes were stimulated solely by the administration of testosterone. 4. By making use of antiandrogens, a distinction can be drawn between the biochemical responses attributable to the binding of 5α-dihydrotestosterone but not of cyclic AMP. Evidence is presented to suggest that the stimulation of RNA polymerase, ornithine decarboxylase and S-adenosyl-l-methionine decarboxylase is a consequence of the selective binding of 5α-dihydrotestosterone. Only the stimulation of glucose 6-phosphate dehydrogenase can be attributed to cyclic AMP or other metabolites of testosterone. 5. Overall, this study indicates that the formation of cyclic AMP is not a major feature of the androgenic response and affects only a restricted number of biochemical processes. Certainly, cyclic AMP cannot be considered as interchangeable with testosterone and its metabolites in the control of the function of the prostate gland. This difference is additionally emphasized by the failure of cyclic AMP to restore the morphology of the prostate gland in castrated animals; morphological restoration only follows the administration of androgens.

The effect of triiodothyronine on cyclic AMP, phosphorylase, and adenyl cyclase in rat heart

1969 ◽  
Vol 47 (11) ◽  
pp. 913-916 ◽  
Author(s):  
John H. McNeill ◽  
Lawrence D. Muschek ◽  
Theodore M. Brody
Keyword(s):  
Thyroid Hormone ◽  
Cyclic Amp ◽  
Rat Heart ◽  
Adenyl Cyclase

Pretreatment with triiodothyronine (T3) greatly enhanced the epinephrine-induced increase in rat cardiac phosphorylase a. T3 treatment, however, did not increase the level of adenosine-3′,5′-monophosphate (cyclic AMP) in rat heart. T3 treatment also did not increase the activity of rat heart adenyl cyclase or change the sensitivity of the enzyme to epinephrine when activity was determined in vitro. It is suggested that if thyroid hormone affects the activity of adenyl cyclase in vivo the effect is lost in the preparation of the enzyme for assay in vitro.

The Role of Physico-Chemical Buffering and of Bicarbonate Transfer Processes in Intracellular pH Regulation in Response to Changes of Temperature in the Larger Spotted Dogfish (Scyliorhinus Stellaris)

1980 ◽  
Vol 85 (1) ◽  
pp. 99-110
Author(s):  
N. HEISLER ◽  
P. NEUMANN
Keyword(s):  
Intracellular Ph ◽  
Heart Muscle ◽  
White Muscle ◽  
Ph Regulation ◽  
Yield Data ◽  
Physico Chemical ◽  
Red Muscle ◽  
Intracellular Compartments

In order to evaluate the contributions of physico-chemical buffering to the adjustment of intracellular pH in response to changes of temperature in tissues of dogfish (Scyliorhinus stellaris), the CO2 equilibration method for the determination of intracellular buffer values was modified to yield data for the mathematical simulation of the intracellular compartments as closed buffer systems, and for the calculation of transmembrane bicarbonate transfer in vivo. The respective buffer values of imidazole-like and phosphate-like buffer substances were estimated to be about 39 and 11 in white muscle, 21 and 18 in red muscle and 27 and 10 mequiv/(pH.1 cell water) in heart muscle. In white muscle, the observed changes of intracellular pH can be explained by physico-chemical buffering and changes of PCO2. In red muscle and heart muscle considerable amounts of bicarbonate have additionally to be transferred across the cell membrane to achieve the temperature-dependent variations of pH observed in vivo.

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